Liquid Rocket Engine Turbopump Gears
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V
FOREWORD
NASA
experience
Accordingly,
has
criteria
indicated
are
a need
being
for uniform
developed
in the
criteria
following
for the
areas
design
of space
vehicles.
of technolgy:
Environment Structures
Individual are
components
completed.
monograph.
of this
This
Guidance
and Control
Chemical
Propulsion
work
document,
will be issued
part
of
A list of all monographs
the
issued
as separate
series
prior
on
monographs
Chemical
to this one
as soon
Propulsion,
can be found
as they
is one
such
final
pages
on the
of this document. These
monographs
are
except as may these documents,
be
uniform
practices
design
to be regarded
for NASA
management
written
by
International technical
was
Martin
A.
Corporation, accuracy
community
of
George
Corporation; Rocket
in detail.
Comments
concerning
National Office), March
Aeronautics Cleveland, 1974
edited
and
the and
Ohio
technical Space
44135.
by
Lionel
as NASA
requirements,
Pratt
B. Keller, engineers and
& Whitney
Buehler W. Drier
content Administration,
of this
Division,
Research
Research
To
the of
Center
the
text.
In
Aircraft of Aerojet
reviewed
will be welcomed Center
assure
technical
United
W. Heath
was
Rockwell
of Lewis.
review
William
monograph
Lewis
Jr.
throughout
Aircraft Lewis
monograph
Division,
critical
Corporation; of the
This
Rocketdyne
Russell and
was prepared under the Lewis Research Center;
Levinson.
Butner,
consultations,
of The Delmar
F.
scientists
of
Glover
Company;
monograph
was
and
Myles
document,
Costomiris H.
not
Turbopump Gears," Design Criteria Office,
Schmidt
and
in interviews,
H.
Wayne
and
vehicles.
Engine Chief,
Harold
and this
participated
particular, Liquid
by
Hartman
to design
project specifications. It is expecte_t, however, that may indicate to be desirable, eventually will provide
space
This monograph, "Liquid Rocket direction of Howard W. Douglass, project
as guides
specified in formal revised as experience
(Design
by
the
the
Criteria
For sale by the National Technical Springfield, Virginia 22151 Price -154.50
Information
Service
GUIDE The
purpose
of this monograph
significant
experience
programs firm
TO THE USE OF THIS
to date.
guidance
and
knowledge and assesses
achieving
greater
greater that
and
present,
accumulated
It reviews
for
product, and major sections
is to organize
MONOGRAPH
current
in
design
consistency
for effective development
practices,
in design,
efficiency in the design are preceded by a brief
and
in design,
and from
increased
effort. The introduction
use
the
operational
them
establishes
reliability
in the
end
monograph is organized into two and complemented by a set of
references. The
State
identifies
the
which
current best
of
Criteria, or
design.
Both
Criteria,
elements.
the
total
design.
When serves
a proper
be
Design
design
problem,
and
succinctly
the
is required,
the
It describes
detailed
information
as a survey
technological
Practices, the
imposed
of the
base
for
clearly
each
serve
procedure
subject
the
that
Design
provides
Criteria
and
3, state
to
the
what
rule,
guide,
element
to
assure
as a checklist
of rules
for the
its adequacy. how
to satisfy
when
Recommended
guidance
briefly
design
effectively
is described; The
and
essential
or in assessing
in section
provided. positive
3, state on
can
a design also
best are
in section
Criteria
in guiding
provide
have'been
similarly
Contents
design
discusses
this
cannot
Practices, practicing
each
of the
be done
concisely,
in conjunction
designer
on
criteria. with
how
the
to achieve
design:
sections
within
The
The
references
successful
in successful
in italics
must
to use
possible,
appropriate
the
shown
Recommended
Design
involved This section
prepares
standard
manager
Whenever
and
to these
are cited. and
reviews
Practices.
limitation,
The
pertaining
material
Design
project
2,
elementsare
references
Recommended
successful
section
design
tecnnology
available
background
The
Art,
numbered displays
can be followed design
specifications,
organized
criteria
this
decimally
numbered
subsections
correspond
from
continuity
of subject
in such
through
both
monograph
or a design
loosely organized its merit should
into
manual.
body of existing be judged on how
sections is not
as a discrete intended
It is a summary successful effectively
to
subsections section
to section.
a way
that
111
the subjects
The
format
a particular
for
aspect
of
a
of
subject. be
a
design
and a systematic
design techniques and it makes that material
to the designer.
so that
handbook,
ordering practices. available
of the
set
large
and
Its value and to and useful
CONTENTS Page
l.
INTRODUCTION
2.
STATE OF THE ART
3.
DESIGN CRITERIA
APPENDIX
A - Conversion
APPENDIX
B - Glossary
REFERENCES
and Recommended of U.S. Customary
Design Criteria Monographs
53
...............
Units to SI Units
93
............
95 103
Issued to Date
Speed Ratio Speed Capability Gear Type Gear Mounting Gear Attachment Backlash Load Capacity Root Bending Strength Face Compressive Strength
Chipping Resistance and Cooling
Heat Removal Scoring Prevention Lubricant Properties Lubricant Delivery System
......
107
.......
STATE OF THE ART
2.1
GEAR SYSTEM
Gear Case
Practices
...........................
SUBJECT
Lubrication
5
.........................
................................
NASA Space Vehicle
Tooth Tooth
1
...........................
6
DESIGN CRITERIA-
3.1
53
2.1.1 2.1.2 2.1.3
10 10 12
3.1.1 3.1.2 3.1.3
53 54 55
2.1.4 2.1.5 2.1.6 2.1.7
13 15 16 16
3.1.4 3.1.5 3.1.6 3.1.7
55 56 56 56
2.1.7.1 2.1.7.2 2.1.7.3
16 18 21
3.1.7.1 3.1.7.2 3.1.7.3
57 59 61
2.1.8
22
3.1.8
63
2.1.8.1 2.1.8.2 2.1.8.3 2.1.8.4
22 23 23 26
3.1.8.1 3.1.8.2 3.1.8.3 3.1.8.4
63 64 66 67
2.1.9
27
3.1,9
68
V
SUBJECT GEAR DETAIL Pressure Angle Number of Teeth Contact Ratio Face Width Tooth Proportions Whole Depth Tooth Thickness Addenda Root Fillet Tooth-Form Modification Surface Tolerances Surface Texture Rim and Web
STATE OF THE ART
CRITERIA
2.2
28
3.2
69
2.2.1 2.2.2
28 29
3.2.1 3.2.2
69 69
2.2.3 2.2.4 2.2.5
29 29 30
3.2.3 3.2.4 3.2.5
70 70 71
2.2.5.1 2.2.5.2 2.2.5.3 2.2.5.4 2.2.5.5 2.2.5.6 2.2.5. 7
30 31 31 31 31 33 35
3.2.5.1
71
3.2.5.2 3.2.5.3 3.2.5.4 3.2.5.5 3.2.5.6 3.2.5.7
72 72 73 74 75 76
2.2.6
36
3.2.6
77
3.2.6.1 3.2.6.2
77 80
Rim and Web Proportions Gear Resonance Tolerances
DESIGN
2.2. 7
37
3.2. 7
80
2.3
41
3.3
81
2.3.1
41
3.3.1
81
Material Grades
2.3.1.1
42
MetallUrgical Properties
2.3.1.2
43
3.3.1.1 3.3:1.2
83 83
2.3.2
43
3.3.2
84
2.4
44
3.4
86
Tooth Finishing
2.4.1 2.4.2 2.4.3 2.4.4
44 44 45 45
3.4.1 3.4.2 3.4.3 3.4.4
86 87 87 88
Shot Peening Configuration
2.4.5 2.4.6
46 48
3.4.5 3.4.6
89 90
2.5
49
3.5
90
2.5.1 2.5.2
49 50
3.5.1 3.5.2
90 91
MATERIALS Gears
Gear Case FABRICATION Forging Tooth Cutting Heat Treatment
Control
TESTING Acceptance Testing Performance Testing
vi
LIST OF FIGURES Title
Figure 1
Schematics
of gear arrangements
2
Relative
3
Gear mounting
4
Schematic
5
Method
6
Allowable
for mounting
Probability
8
Allowable
9
gear
and Saturn IB boosters)
.......
14 15
....................
vs root bending
quality grades
compressive
12
18
........................
of tooth breakage
four material
.........
stress vs cycle life for gears of
quality grades
of four material
velocity
9
13
(Atlas, Thor,
a detachable
root bending
of pitchline
.........
.........................
of Mark 3 turbopump
four material 7
in major operational _urbopumps
usage of gear types as a function methods
Page
stress for gears
19
.......................
stress vs cycle life for gears of
quality grades
20
........................
Probability of tooth pitting vs compressive stress for gears of four material quality grades .......................
10
Sketch illustrating
terms and symbols for tooth proportions
11
Addenda
12
Sketch illustrating
terms for gear surfaces
13
Sample inspection
charts for involute
14
Sketches
15
Sketch illustrating
16
Sketch
of gear arrangement
17
Sketch
showing locations
18
Sketch illustrating
19
Recommended
values for equal strength
illustrating
vs number
30
..........
of gear teeth (20 ° PA spur gears)
....
and lead
................. (original
grinding zones on critical hardened in a back-to-back
tip, edge, and end radii
34
and uprated gears
gear tester
for case depth and hardness
designs)
.....
............
tests
36 47
...........
51
............
62
..............
root fillet radii vs number of teeth (25 ° PA spur gears)
vii
32 33
...................
rim and web dimensions
gear-tooth
21
62 .......
73
Title
Figure 20
Acceptable
21
Sketches
22
Recommended
23
Cross-section
and unacceptable illustrating
recommendations
locations sketch
lead traces
for stock
of a forging
75
................... for design
removal showing
Page
of lightening
for balancing proper
Vlll
grain flow
holes
............. ............
........
78 79 86
LIST OF TABLES Page
Title
Table I II
Gear System
Gear Design Data for Major Operational
III
Characteristics
IV
Tooth
V VI VII VIII
Data for Major Operational
Factors
Involved
Properties
in Various Gear Scoring
of Turbopump
Gear Manufacturing
Gears
Indexes
.............
Materials
for Turbopump
Gears
Preliminary
38
Dynamic
Load Factor
XIV
Overload
Factor
and Pumped Preliminary
on Gears
._ . .
49
Case Depth to Ensure Adequate
(20-Percent
..........
Conditions
...........
Type
Compressive
61
...............
XVII
Recommended
Tip, End, and Edge Radii for Gear Teeth
...........
XVIII
Recommended
Limits on Three Types of Scoring Index
..........
XIX
Recommended
Values for Gear Surface Roughness
ix
58
59
................
Stock Removal Allowance)
57
58
.....................
Design Values for Pitting Index K
40 41
...................
Kv for Various Operating
. . .
..........
......................
Ko Related to Pump and Turbine
Fluid
Recommended Strength
39
Design Limits for Face Load and Unit Load
XIII
20
25
.................
Measurements
Sample Data Block for Gear Drawing
8
24
...............
.....................
Laboratory
7
11
.................
Accuracy of Measuring Equipment Used to Inspect Production Runs of Gears ........................
X
XVI
..........
Gear Lubricants
Tolerances
of Metrology
XV
Geared Turbopumps
Pitting Index K for Current Turbopump
Accuracy
XII
..........
of Speed Ranges for Gears
IX
XI
Geared Turbopumps
..............
63 65 76
Title
Table XX
Recommended
Rim and Web Thicknesses
Web-Lightening XXI
Recommended
Holes
Page
and Number
of
..................
Materials
........
and Material Requirements 82
for Turbopump
Gears
XXII
Recommended
Hardness Values for Carburized
XXIII
Recommended
Hardness for Material Grade 3 Gears (Carburized)
XXIV
Recommended
Processes
Turbopump
Gears
79
.........................
and Process Controls
Gears
83
............. .........
84
for Fabricating 85
...........................
x
LIQUID
ROCKET
ENGINE
TURBOPUMP
GEARS
1. INTRODUCTION
Gear drives for to medium-power
propellant pumps handling rather greater) are to be driven by a small,
(2)
a single
turbine
densities
that
engines,
a rather
unique
of
duty
cycle
turbopump
and
on
life
to 500
gears
to
reliability
High
load
• •
High speed Short life
•
Light
design, testing forth proven
1Factors
conditions
including
gear
with
hour.
combination
with
drives
greatly
or
differing
for turbopumps,
a rapid
start
testing
extends
Performance
from
imposed
have
standstill,
for
the required
life
requirements
of requirements
for turbopump
in gear
of usefulness
and
processing,
that explored the technology
for converting
0.7
or
propellants
Acceptance
one
gravity
for
flight
on a turbopump
capability
advances
materials,
The development problem areas:
approximately
(specific
in low-
speeds.
operation,
duration.
efficiency
weight
required
procedures
infallible seconds
maximum
capacity
operating levels
pump
handling
components
low weight. The up as follows:
High
acceptable
their
to achieve
dense propellants high-speed turbine;
turbopumps
different
requirement:
•
them
require
of up
•
unusual
is to drive
therefore
naturally emphasize gear can be summed
The
turbopumps are used to 4500 hp) 1 when
(1)
Rocket one
rocket engine drives (100
technology.
reliability
and
gears
quality
and
the
Turbopump
through control
severe power
refinements combined
requirements gears
were
imposed brought
in interdependent with
extensive
areas
to of
development
problem areas and evaluated potential solutions. This monograph sets developed to date, identifies the problem areas, and summarizes for successful of
gear design.
gears
for
U.S. customary
units
turbopumps
to the International
required
System
solutions
of Units
(SI units)
in
the
are given
following
in Appendix
major
A.
(1)
Tooth
(2)
fracturesimprovement
process, and Compressive
shot peening. contact failures
addendum
improved
material
Scoring
in
lubricated
effects
exciting
forces
for
purpose
this
profile,
These
problems
and
include rim
close
techniques;
tolerances-
and
turbopump
web
are
not
control
by
of gear geometry lead
'control
of
in the design the
number
thicknesses,
of
surface
texture,
or the
elements. teeth,
delivery
frequency
Design
dampers,
or
the
additional
independent,
equipment
factors
tooth
reducing
the
members.
entirely
in
of
variations
modifying
and
some
mutual
benefits
the overall success of the gear depends on minute materials, rigidly controlled in quality; closely precision
such
modification;
of lubricant
magnitude
adding
rotating
of manufacturing
and
of the gear
the
gear
of dimensions.
advances
response
of
in
and
techniques
successful
for
design
and
designer
take
attention controlled monitoring
production
of
gears.
To
obtain
the
turbopump
should
are
the
of the
increased
all
controi
modifying
changing
limits
solutions
by
rigid
modification
by improvement
rigid and
eliminated
of
modification,
gears-eliminated
accrue from each improvement; to details in all areas. Graded fabrication
and
lubricants,
-
imbalance
cleanliness,
profile
or by altering
altering
allowable
a combination
- eliminated
Cleanliness;
of better
systems. Vibrational
by
in material
proportioning,
development (4)
eliminated
dimensions,
as (3)
root
an optimum
take
gear design,
preliminary the
following
(1)
Reduce
the
(2)
Determine
(3)
Minimize
(4)
Guide
(5) (6)
Provide Ensure
pitchline the
velocity
lightest
that
the
gear
in basic
decisions
that
lowest
realistic
value.
an active
influence
the
part
in
gearing.
He
to the
weight
gear design
that
can safely
be used.
of gears.
turbopump
layout
for balancing that provisions
delivery
by aiding
steps:
the number the
it is essential
design
designer
as required. are made
for
in selecting the
the
use of the
proper
proper
gear
type
lubricant
and
and
size.
lubricant
system.
(7)
Minimize
(8)
Ensure
practical
all external and
forces
(9)
Ensure
a rigid
mount!ng
easy
reacting
on the
methods for the
of gear, gears,
and
gear
casing.
bearing, avoid
shaft, design
and
gear-case
practices
that
assembly. cause
gear
misalignment. (10)
Ensure
by
meshing After
the
individual satisified
with
or
frequencies
turbopump gear
analysis
design all fits,
that
or operating
layout and
test
has
detailing,
finishes,
and
been
gear
system
resonances
do
not
coincide
with
speed. adopted,
reviewing clamping
the all
methods
2
gear
designer
dimensions. used
on
In
must
addition,
components
supervise he that
should
the be
will affect
the gears.The designer should continue to monitor gear designand development through final production release. Operational problems should receive his prompt analysis for possibledesignchangerequirements. This monograph treats gear designand fabrication in the sequenceencountered during the design process: selection of overall arrangement,selection of gear type, preliminary sizing, lubrication system design, detail tooth design, selection of gear materials, and finally gear fabrication and testing as it affects the design.There is, of course,a good deal of cross-feed amongthe phasesof designand, accordingly, the monograph frequently cross-referencesand dovetails related material. The monograph is oriented toward the useof involute spur gears, although referencematerial for helical gearsis cited.
2. STATE OF THE ART
Satisfaction
of
following
the
severe
requirements
imposed
on
turbopump
gears
depends
on
the
the
potential
of
the
factors:
(1)
A design
(2)
Gear
that
is technically
materials
and
adequate
manufacturing
processes
that
exploit
design (3)
Quality-c0ntrol
procedures
dimensional nondestructive Favorable forms
features
long
addendum
increase
equipment specified
and
the
are
of gear surfaces
gear-tooth
roots
generous
and
of
shot-peening
can
° to
and
reduce
and
proper
monitored
by
tooth
modifications.
Tight
Special
measuring
procedures
mechanical
by specifying
the
full-depth
stresses.
plus standardized
uniform
be
27.5°),
profile
peak
to
ensure
that
properties
is ensured
representative
tensile
by tests
gear webs
often
the
frequently
with
forgings
root
specifically
are
dramatically
increases
gear
dynamometer
success
to avoid of one
of
and
test
particular
data.
lubrication
of a design seemingly supplier's
Such
has
been
unexplainable gears was
flow.
loading
peening
is an effective
tests
have
to incorporation
been by
failures. traced to
Shot
economical
prior established
design.
Gear-tooth of
life.
enables
features
successful
grain
not ground.
or back-to-back
in
for
specified
fillets
configuration amount
is necessary
with
test,
used
design
and
rapid
extensively into
process
the
in final
uniformity
For example, a sudden drop variations in a nonuniform
process. and
lubricant
delivery
gear
capacity
led to improved also is used
but
processing,
must be maintained in the fatigue life
Lubricants
are ground,
a large
after
method
close-tolerance
service
design, Even
and
that
(22.5
fillets,
and
steels
manufacturing
back-to-back
accumulation evaluating
root
accuracy
adequate
conformance
processes
angle
of operation
with
from
in simulated The
A typical
pressure
vacuum-melted
machined
contacting
design.
large
consistent
analyses.
Specification
aid.
fabrication
pinions,
of materials
metallurgical
Testing
and
smoothness
mill-lot-controlled,
Gears
include
ensure
with increased sensitivity and tolerances actually are obtained.
Procurement using
tolerances, tests.
design
with
tolerances
that
load
to monitor sequence
lubricant
of actions
systems with quality
in the
have
been
conventional and
design
the and
subject
of development
unconventional
testing
lubricants.
that
Testing
effectiveness. and
manufacture
of aerospace
gears
is as follows:
After engineperformance considerationslead to the selection of a geareddrive transmission, the generalfeatures of the gearsystemare determined: basicgeartype, the sizeand number of gears, and the speedsand rotational directions of the shafts. The gear design then progressesthrough preliminary determination of operating stressesto detail selection of pitch, number of teeth, profiles, required modifications, material selection, and creation of manufacturing drawings and specifications of materials and processes.Acceptancetests and performancetestsusedasdesignaidsconcludethe geardevelopment.
2.1
GEAR
Trial
layouts
attempt
of
the
the
desired
speed
compact
ratio
•
Gear-tooth
load
•
Gear
capacity
• •
Practical Minimum
distance speed
and
design
therefore
of the
Particular
care
rotational
gears
dictated
features
of and
appear
Nomenclature
delivery
system.
materials;
during pumps,
I. Table
stresses.
used
Manufacturers
1Symbols;
factor effort
in figure
within
ducts
provides thereof
adequate then
constraints
guide
the
spacing
are selected
imposed
to
by
design
to avoid
undercutting.
in achieving
success
is expended
to ensure
turbines, and
and
is noted
the views
tables
figures
that
of
the
arrangement
for
existing
detail
design
gear
high-speed
of lubricants
Direction
of
on assembly
systems gear
selection
the gear
specifically
major
Schematic
in the
accessories.
gear
II lists
in high-power
trains
and
obtains rotation
gear in
proper often
is
drawings. major values
used
turbopumps of power,
are speed,
in major
turbopump
is based
on American
1.
in the
Association
specifications;
that
diameters
and
available
main-power-transmission
lubrication,
the
direction
gear size of pinion teeth
requirements
in table
turbines,
arrangement and
rotation
considerable
of
summarized systems
and
is a major
is exercised
by engine
physical
pumps,
capacity
lubricant
direction
including
of gears
and volume
maximum number
of the
system
number
Center
systems,
B.
most The
•
Lubrication
Gear
turbopump
components.
achieve
The
the
to achieve
of these
the
SYSTEM
vehicles,
and
and
(AGMA)
standards
pumps,
and engines;
throughout (ref.
the
1) except
and abbreviations
used
text
where
noted.1
herein
are identified
in Appendix
Table
Speed
t. -
Gear
System
Data
for
Major
Lubrication
reduction ratio
Input speed,
(system)
rpm
Input/pump-shaft
Power
Oxidizer
Fuel
hp
Atlas
4.885
4.885
4920
Gearcase
supply
internal
gpm
pressure, psig
pressure,
RP-1 and
psig
Gear
material
Gearbox
weight, Ibm
6265
150
5.5
620
4.0
AMS
1.2
625
1.4
A_MS 6265
Specified
Attained
3750
>
6500t3
6000
>
20 000
extremepressure additive
3) sustainer
(Mark
Life,
Lubricant
Lubricant
boosters (Mark
Turbopumps
system
flow,
transmitted,
32 730
Atlas, Thor, Saturn 1B
Geared
sec
Lubricant
Vehicle
Operational
38 085
3.750
3.750
a
MIL-L-
1650
approx.
4)
40
(gearbox unitized)
6086 or MIL-L-
not
25336
Titan
23 000
II, 1st
2.87
2.62
MIL-L-
4466
stage (LR-87-AJ-5) Titan
3.4
15.0
30
AISI 4620
II, 2nd
22 800
2.82
NA
924
MIL-L-
stage
or
228
2500
> 6000
114
2500
>
9310
7808
1.5
30
15.0
0.4
40
3.5
AISI 4620
6 0130
7808
(LR-91 -A J-5) Centaur
30 000
2.50
1.00
80
Dry film b
(RL10)
9310
24 800
1.721
0.977
357
(LR81-BA-11)
a 98%
RP-1
b 25%
powder,
= not
plus
available.
2% 75%
Oronite AMS
262 3132
(zinc
dialkyl
varnish,
AMS
MIL-L-
1500
7808
dosed
cm 3,
Not plied
sup-
system
pressure
under
Does not
thinner
as required.
The
powder
consists
of
10
parts
MoS
2 and
1 part
graphite
by
case is part of
weight.
420
20 000
case
AMS 6250 NA
apply
dithiophosphate). 3170
Gear engine
and hydrogen
Agena
NA
AISI
NA
NA
Table
II. -
Gear
Design
Data
for
Major
Operational
Geared
Turbopumps
Sur_ce
Vddcle (system) Atlas, Thor, Saturn IB boosters (Mark Atlas (Mark
oo
3) sustainer 4)
Titan II, 1st stage (LR-87-AJ-5)
Gear (fig. 1)
II, 2nd
stage
(LR-87-AJ-5)
Centaur
(RL10)
Pitch
velocity, _/min
diameter, in.
Diametral pitch, in.- 1
Number of
Power, hp
Speed, rpm
A
4 920
32 730
9 474
25 727
3.00
11
33
B C
4 846 4 846
15 430 15 430
19 793 19 793
25 727 16 676
6.36
11
4.125
D
4 777
6 700
44935
16 676
A
1 650
38 085
2 730
B
1 650
10 157
I0 230
A
4 466
23 000
B
2 320
11 000
C
2 146
Tooth
face
compressive
Pressure Unitload,
stress,
width, in.
angle, deg
1.44 1.32
25
48 247
263
067
70
25
52 633
263
067
8
33
1.46
52 584
263
067
9.50
8
76
1.64
25 25
46 146
263
067
20 000
2.00
12
24
1.12
25
29 200
20 000
7.50
12
90
1.00
25
32 800
12 200
16 600
2.75
11.25
31
2.125
185
000
16 600
5.78
11.25
65
1.99
20 20
26 100
13 300
25 600
191
000
8 010
16 900
16 600
16 600
16 600
89 81
20
8 800
11.25 11.25
2.00
2 320
7.91 7.20
2.125
20
25 500 26 108
175 000 142 000
A
924
22 800
2 550
16 400
2.75
12
33
1.00
173000
924 924
10 900 8 100
5 340 7 190
16 400 16 400
5.75
12
69
0.875
20 20
22 300
B C
25 500
184 000
7.75
12
93
1.00
20
22 300
129 000
D Titan
Torque, m.dbf
Pitchline
I
teeth
psi
psi
A
80
30 000
167
15 720
2.01
13.96
28
1.20
22.5
2 140
56400
B C
80 80
12 200 12 200
414 420
15 720 15 720
4.94
13.96
22.5 22.5
56 400
13.96
1.10 0.70
3 340
5.01
69 70
3 350
53 600
20
16 200
121000
20 20
12 700
120 000
16 200
126000
Agena
A
357
24 800
907
17 400
2.6875
16
(LR81-Bg-11)
B C
157 200
25 300 14 410
390 874
17 400 17 400
2.625
16
43 42
0.500 0.375
4,625
16
74
0.375
0
T
Atlas, Saturn
F
Atlas
Thor, and IB boosters
Titan
sustainer
II,
B
T
0 A Titan II, sta_e and Centaur
A,
B,
Figure
C,
Agena
2
D:
gear II)
identity
O:
oxidizer
F:
fue i pump
T:
turbine
(used
in
table
pump
1. - Schematics of gear arrangements turbopumps.
9
in major
operational
stage
1
2.1.1 Gear
Speed Ratio
trains
optimum
in rocket turbine
main-power-train lubrication through The
following (1)
speed
ratios
for
hydraulic
limitations must
usually
is
common
be
gear
and
electric
on speed number
and
is
in a mating
Multiple
reductions
strength
and
are
a
are
normally
speeds.
turbopumps.
generators
Accessories
driven
high
Table
at the
I lists such
desired
as
speed
ratio: of
teeth
obtained
required
on
by
each
gear;
choosing
to obtain
tooth
single
driven
matching
pump
hunting-tooth
numbers
of
action
teeth
with
no
set of gears.
nonoptimum
in
permit
optimum
trains.
a whole
desirable
drives
lower
major
pumps, gear
much
are imposed
factors
attempted
main-power
normally
accessory-drive
There
(2)
turbopump
with
pumps, smaller
engine
speeds
mesh.
action
In
large will
general,
overall
result
ratios.
if
too
a maximum
Losses
large
ratio
in tooth
a reduction
of
is
5 per
mesh
is
the
minimum
permitted. (3)
The
number
number
Although
the
flexibility
in engine or
fixed
for
Gears
to avoid
speed
of
performance
a gear
most
are
the
be
maintained
teeth.
above
Minimums
for varying
gear
sizes
5).
if a change
For
balance
must
weakening
2 (ch.
ratio
pinion
train
in relative
rocket
made
often
engines
by trimming
is an asset, output that
pump
the
is required use
fixed
impellers
fixed
ratio
limits
for a performance mixture
or by
ratios,
changing
fine pump
Speed Capability
have
at higher ranges
been
designed
speeds with
velocities R&D
in the
in reference
throttling.
adjustments in flow discharge orifices.
2.1.2
teeth
required
are given
change
of
tests
and
is so difficult
corresponding
up
to 25 727
indicate
that
operated
at pitchline
velocities
as to be impractical. risks,
ft/min
have
these
gears
requirements, been
utilized
can operate
10
Table and
up to 50 000 III
lists
potential
in operational satisfactorily
broadly
ft/min;
classified
problem
areas.
turbopump
gears
at speeds
operation speed Pitchline (table
up to 27 200
II);
ft/min.
Table
III.-
Pitchline velocity, ft/min 4 000 to 15 000
Characteristics
of Speed
for Gears*
General classification Characteristics
of speed range Normal
is required.
First reductions of turbine-driven pumps are in this range. Centrifugal stresses can cause problems. Gear tooth accuracy is critical. Dynamic balance is important. Rela-
High
tively few manufacturers 25 000 to 30 000
and hazards
These speeds are representative of those attained with most high-speed gears. Centrifugal stresses cause no problems. Many manufacturers are capable of building the units. Dynamic balancing is not critical. Moderate gear tooth accuracy
15 000 to 25 000
Ranges
Very high
are qualified
and experienced.
These speeds generally are found only in rocket engine and aircraft gas turbine test rigs or in large industrial gas turbine drives. Centrifugal stress problems are critical. Failures are potentially dangerous to human life because of probable casing rupture. Solid rotor designs usually are required for the gear. Gear tooth accuracy is critical. Lubrication is critical because of windage problems and possible excessive temperature rise on working tooth surfaces. Rotors must be balanced to fine limits. Few gear manufacturers are qualified
30 000 to 45 000
Ultra high
to fabricate
gears for this speed range.
This is the "frontier" area of extremely-high-speed gears. Failures are highly dangerous. Even the best solid rotor designs may rupture because of small metallurgical defects. High-speed balancing techniques are required. The best gear manufacturers in the United States have had some successes and some real problems in the few special aerospace gears that have been fabricated. No turbopump plications in this speed range are in use.
*Adapted
from
a report
presented
by D. W. Dudley
at ASME
11
Annual
Meeting,
1966.
ap-
2.1.3
Gear Type
Turbopump types.
main-power
For
of the
most
center
distance. efficiency
tooth
action
designed of
rather
3 gear
loads
new
(table
and
The
choice
between
higher
used
used
and
II)
will make
and
spur
as pitchline
10
\
velocity
increases.
types
in power can
be
10
2O
Pitchline
velocity,
2. -
tests
gears and
power
have
been
for accessory
increments spur
shown
despite
gears for the
the
cost
of a
2 presents
gearing.
velocity.
more
bevel, because
used
for
drive
gears
drive
the relative
helical usage
of
Single
helical
Double
helical
ft/min
Smoothness
as
trains
on speed,
50 x 103
usage of gear types
transferred
is based
Spur
40
pitchline
such
Bevel
Figure
Relative
Non-coplanar
gearing
in table originally
existing
attractive
I
30
in a non-turbopump of 6 when helical
main
shown were
,J I
overlap. For example, was reduced by a factor
turbopulnp
smoother
gears
the level
in
of their
levels
in moderate
improve
--0--
2
loads
place
normally
- .orl 1
Figure
two
and
beyond
gears
I
4
0
the
capacity
speed
one
variations
load
i
6
of small
because
and
uprating
of other ranges,
trains
and
took
exclusive
power
turbopump
to adapt
configurations
0
gearing;
power most
of helical
; \/o r-4 ID ¢lX
high
tooth
f
8
ID
temperature
higher
as uprating
the use
J
ID tan
their
Further
gears
is its tolerance
Hqwever, desirable
spur wide
of manufacture.
helical more
present
designs.
and
to turbopump
with
speeds;
more
helical
cost
gears
if the
loads
gearing
applied
requirements.
involute
high
of involute initially
economically
train
design
being
been
coplanar
involves
helical
design
modest
to initiate
new
gears
have
more
were
simplicity;
initial
it was
than
Mark
the
which
features
gears
and
for
power,
Spur might
been
incorporate
gearing,
advantageous
high II had
trains
turbopump
as a function
of operation gradually
to
of
is a definite successive
teeth
advantage
of helical
because
of
power-gear application, vibrational gears were substituted for spur gears. worm,
and
of their
lower
connections
in turbopump
12
hypoid
gears
efficiency
to power systems.
trains
have
(increased
not heat
tooth
amplitude
been
used
generation).
for hand-rotation
torque
in
2.1.4
Gear Mounting
Figure
3 presents
three
methods
for mounting
gears.
-_0.7D
to
1.0D
_Gear
and
bearing
I
(° I' ii
D
-I S
(a)
=
0.6D
Straddle
mount
(b)
Overhung
(c)
mount
Mount
for
with
single
idler
gear
bearing
Figure 3. - Gear mounting methods.
Straddle
mounting
under are
load
that
general
(fig. cause
rigidity
individual
application.
Overhung
mounting is the
mounting, mounting
the
and
are
turbine
actual
3(b)) shaft
shown
in the
figure,
Mounting
of idler
the
gears.
This
configuration
teeth
line
up
Rkl0 gear
capacity, of the
since bearing
detailed
misalignment.
are
the
result
calculations
when
4 (Atlas
General
but actual
in order
and
is used
Mark
is sought.
under
idler
dimensions
sometimes
deflections
possible
distances
after
of the
rigidity
whenever
in center
selected
(fig.
maximum are
is used
changes
guidelines;
mounting
example
3(a))
sustainer)
dimensions
The of
and
saving
to
maximize for the
is a major
turbopump. from
shown
deflection
goal.
As with
for proportions result
deflections
proportions
attempts
of stress
space
guidelines
to minimize
An
straddle
of an overhung
detailed
analyses
of the
load. gears
the
on
with
tangential
is shortened
a single
ball
bearing
tolerates the
driving
forces
on
by rotation
3(c))
misalignment gear
the
(fig. teeth.
idler
of the outer
13
gear
has been
used
by rocking A potential
teeth
race.
advantageously
the
ball
problem
are additive.
bearing area
In addition,
on so the
is bearing the
life
ii
Cryogenic mounting
volute pins Mainshaft
Liquid
gear
oxygen
\
pump
Fuel
pump
Intermediate and with 4_
Accessory
gear
High-speed with
("A")
integral
pinion
bearing
races
Quill
Figure
4. - Schematic Saturn
of
Mark
IB boosters).
3 turbopump
shaft
(Atlas,
Thor,
and
accessory integral
("B-C" drive bearing
gear pinion) races
2.1.5
Gear Attachment
Secure will
attachment
create
additional
mounting to
make
gears
in the
cluster
gears.
If
gear
the
Mark
must
shaft
is necessary
deflections.
surfaces.
been
the
of the
Relative
In extremely
highly
gear
with
integral
3 turbopump
be
for gears
removable
motion loaded
its trains,
from
the
the
shaft,
-
used.
Radial
through between fretting increasing
position
the
spline.
stacked of
the the
The
faces
of the
clamping-nut
_
for
mounting
by
clamping-nut
components
_
Method
is maintained due Mark
example,
"A"
pinion
the
mounting
solution
figure and
and
the
method
looseness
damage
to the
to fretting
4 shows "B-C"
any
the
has
one-piece
accessory-pinion
shown
in figure
5 is
the
spline
is made
thrust
4 (Atlas
a detachable
tight-fitting
torque to
in fretting
a satisfactory
For
because
Loose fit
pilots
5. -
loads,
_.+__._
Tight fit
Figure
high
will result
gears,
shaft.
gear
under
loads, sustainer)
torque.
15
gear.
pilots; high
driving
enough
bending, turbopump
or
torque
to prevent thermal pinion
is transmitted relative
motion
expansion. was
eliminated
Severe by
2.1.6
Backlash
Backlash
is the
clearance
between
contact
on
stackup, indicate
differential thermal growth, and the need for a change in backlash.
interference,
Gear
nondriving
high
side
forces,
and
of
heat
of a given
backlash the
(ref.
gear
and
under
lubricant Absence
any
to lockup
tooth
thickness
in the
design
combination
of
film buildup. of backlash
leading
the
1) is provided
tooth
generation
gear
of
to avoid tolerance
Test experience will lead to actual
and
gear
may gear
failure.
Load Capacity
tooth
mechanical
maximum tooth the
sufficient
width
gear. the
but
space
meshing
2.1.7
Minimum
the
capacity
details
(sec. 2.2),
required
been
gear
uprated;
considered
in the used
designed
for
10 years
to handle
increase
required
fabrication experimental Tooth
nearly
improvements changes
recognizes
that
uprating
train
Thor,
in were
and
II). The
materials, then
Further,
development IB
over
a period
detail
is the
are
Mark
3
Originally
of approximately nature
design,
into
has
changes
boosters.
incremental
gear
turbopump
design
Saturn
consolidated
achieving (sec. 2.1.9),
in determining
every
future
of evolutionary
(table
However, alignment
nearly
through
was developed
horsepower
capacity.
(sec. 2.1.8), (sec.2.4).
Atlas,
gear
load
fabrication
example the
the
these
and
designer
An
of gear
lubrication
for
for
5000
small
of the
power
lubrication,
design
and
requirements
after
verification.
mechanical
strength,
and
compressive
strength
the on
is composed
the'tooth's stress
reliability, depends
design. engines
horsepower,
techniques;
the
provisions
the
basis
(sec.2.3),
capacity,
original
1800
the
optimizing
materials
load
in
forms
requires
therefore,
gear
train
strength also
gear
the
resistance
levels
depend
material
material,
of
root
bending
to
chipping
of the
on the
required
life
quality its heat
level,
and
treatment,
strength, edges.
compressive
The
(number
allowable
of stress
manufacturing
tolerances.
and
of stress
avoidance
contact
bending
cycles),
the
Chipping
and
desired
resistance
concentrations
at the
edges.
2.1.7.1
TOOTH
Since
a gear
larger
tooth,
ROOT
tooth
BENDING
is similar
designated
relationship
is reflected
gear tooth defined as
strength
by in the
used
STRENGTH
to a cantilever a gear
beam,
numerically tooth
in preliminary
physical
smaller breakage design
16
size
diametral
index,
"unit
calculations.
is an index pitch, load,"
Unit
of strength;
is stronger. which
load
for
a This
is a gauge spur
gears
of is
Wt Pd U L
-
F
where UL = tooth
breakage
total
tangential
W t =
F = effective
face
index,
or unit
tooth
load,
width,
load,
psi
lbf
in. number
Pd = diametral
pitch
of gear tooth
pitch Turbopulnp The
gears
resulting
short
use
required
materials gears
and
classes
in table quality
Refinement
of unit the
The
AGMA
cantilevered [spur Values
for
large-scale factors factors
are
(K,,,), from
Tests
used
and
of
account
Digital
have
the
and
In lieu
reference
of root
by the
imposed
turbopump
material
on
power
quality gears
of 12 500.
are listed
gears.
grade made
of
Reference
as AGMA
3
quality
stresses
geometry
is obtained and
by
by
derating
alignment.
the
gear most
methods
the
basis
and
geometry
dynamic the
values,
and
to be the
by
provides
bending
tooth
to
accurate
be
a shaped
available
(refs.
5
8.
A
gears]).
calculated
are
possible
control
Accessory
load
tooth
assume
bevel
possible,
unit
for
3
(Y factor)
sometimes
of 25 000.
of service,
tooth
of empirical
programs
estimate
severity
size (Ks),
of AGMA
tolerances
this approach
When
is made
for existing
load
for aircraft
and 4.
form
for
(Kt).
saving
loads
made
compensating
7 [spiral are
gear tooth
to account
colnputer
shown
stress
for
temperature
experience.
in
gears],
bending
layout that
outlined
6 [helical root
quality,
used
quality
to a maximum
9-19)
those
stringent
Unit
Dimensional
accurate
factors
than
weight
gears
to a unit
through
by
on the gear
plate.
gears],
gears.
grades.
to a more
higher
more
similar
1 are limited
9-16
load
methods
and
limited
in.
consequent
features,
quality
load
unit
dependent
are
grade
2 (pp.
lnultiplying
the
loads
for turbopump
material
in references
and
II. Geometrically
generally
aircraft
factors
gears
diameter,
for unit
design
manufacturing
material
discusses
designed
special
quality)
AGMA
are
of smaller
life,
are listed
2 (aircraft
often
of teeth
=
for
loads values
suggested
utilized
presented selecting
in the
(J factor).
(Kv),
overloads
for the
modifying
values
given
to determine
reference
stress-modifying
Further (Ko),
misalignment
factors
in reference
form
and
modifying are derived 8 are used.
geometry
factors
for gears. Allowable by
test
processes allow
values for
for gear-tooth-root
carburized
(e.g.,
shot
use of higher
and
nitrided
peening), stress
and
bending steels
stress (refs.
tolerances
for given 3 and
developed
levels.
17
9). and
cycle The
life have
been
special-quality
refined
for
established materials,
turbopump
gears
Figure
6 presents
tile allowable
bending
stress
as a function
of the
cycle
life fox" carburized
150 x 103. c/l
100 laO r_ .r-I
--
80
g -O
60
g %
50
,,
o
,,,,,I
10 3
I
I0 _
105
I
I
106
107
I 108
109
Cycles
Figure
6. -
Allowable gears
steels
used
quality
in aerospace
grades
gears
1 and
2 are
taken
from
3 represents
the
stress
levels
grade
4 represents
the
levels
attainable
and
technology.
gear
altered
quality.
to obtain
2.1.7.2
TOOTH
Gear
tooth
that
is used
Figure
Note a linear
FACE
capacity
that
with on
COMPRESSIVE
3 and
the
the
finest
probability
the
life
grades.
for
The
represent
for turbopump
the relationship
to withstand
in preliminary
scale
vs cycle grades.
quality
reference
attained
stress quality
material
7 relates the
plot;
bending material
of various
grade
lubrication
root
of four
gears available of tooth
abscissa
is not
presented
stress
aircraft under
values practice.
present
design,
Material
practice,
and
manufacturing,
breakage
truly
for AGMA
logarithmic
and
to bending
stress
but
been
has
is nonlinear.
STRENGTH
compressive
stress
is reflected
in the
tooth
pitting
index
designs:
-K = Wt(me+l) Fd \ mG
(external
-K = WtlnG Fd mG-- l )
(internal
18
gears)
gears)
(2a)
(2b)
K
ii0
I
xlo3 i00
_
I
I
_ 1_'4't/
_e_s
_"
_i
9O
J c'l ©
80 C -M
,o
7O
_o
6o
I
5o
I
0.i
o.oi
Probability
Figure
7. -
of tooth
Probability stress
of
for
Wt = total
pitting tangential
F = effective d = pitch m(;
index,
face
diameter
= gear ratio
=
tooth
gears
of
width,
dimensionless load,
number number
lbf
in.
of pinion,
in.
of gear of pinion
5 breakage,
tooth
where K = tooth
I
i
teeth teeth
19
breakage four
material
I i0
20 x 106
cycles
vs
root quality
bending grades.
Table
IV
presents
the
Table
Type
K values
IV.
-- Tooth
used
in current
Pitting
Index
turbopump
K for
PLV,
of gear
gears.
Current
Turbopump
mG
power
For
preliminary
for
25 ° PA
applying and by
derating
quality the
Figure
design, gears,
(refs.
methods 8
presents
2.1
2.75
21 000
3.75
2.00
1 800
27 000
2.1
3.00
2 050
13 000
2.3
4.12
2 500
1 tO5
1 to6
to 7 000
0 to 100
Actuator
the
and
as
tooth 7100 depending
10
1 1).
given
in reference the
allowable
contact
For
on
compressive
final
20 ° PA load
values
to 1 000 2 000
stress
gears;
may
a closer
application,
design,
500
2.5
oo (rack
K '/2 for
factors and
1 200
18 000
2 000
Accessory
K
67
in.
ft/min
Main
Gears
be estimated
misalignment, for
as 6500
determination
compressive
K V_
is made
surface stress
conditions are
calculated
1 1. compressive
stress
level
as
a
function
of
cycle
life
.el
bOO x 103 %
3oo --
gl
200 --
I
I
I
I
I
|
-4
E O O
,13
o_ 100 l03
by
I
I
I
I
I
i0_
105
106
107
108
Cycles Figure 8. -- Allowable
compressive
gears of four
2O
material
stress vs cycle life for quality
grades.
10 9
for
carburized steels used in aerospace therein for AGMA quality grades
gears 1 and
of various material quality 2 are taken from reference
grades. 3 and
The stress values represent aircraft
practice; the stress values shown for the material quality grade 3 in figure 8 are allowable compressive stresses for turbopump gears designed and fabricated with present practices; the curve labeled grade 4 represents the stress levels attainable with maximum use of presently available technology in design, manufacturing, and lubrication. Figure 9 presents the probability of tooth pitting as a function of compressive stress (as before, the scale has been modified to obtain a linear plot).
350
x 103
I
I
I
I_
325300
°
1
250
225_ 200 0.01
0.I
i
Probability
Figure
9. -
Probability stress
2.1.7.3
CHIPPING
potential
nitrided process.
for
case; the Chipping
of tooth
of
tooth
I0
pitting,
pitting
gears of four
20 x 106
cycles
vs compressive
material
quality
grades.
RESISTANCE
Chipping of tooth edges may loss of load capacity because gear system. The
for
5
chipping condition tendencies
result in progressive degradation of reduced load-carrying surface
exists
in nitrided
is aggravated are reduced
gears
by by
21
the
because corner
of the gears as a result and (2) contamination
of the extreme buildup
that
occurs
brittleness in the
of (1) of the
of the nitriding
• • •
Limiting case depth in thin sections Establishing a minimum tooth tip width Providing adequate radii and blends at corners
Tip, end, and edge radii on the gear tooth of active surface resulting from unacceptably insufficient radii. Because these radii often prevent wide variation. On critical gears, radii
Chamfers are avoided are established before
as a final
finishing
2.1..8
Lubrication
of tooth
tips,
ends,
and
are controlled carefully to prevent large radii or stress concentrations are hand ground, careful control
edges.
excessive loss arising from is exercised to
because they can lead to stress concentrations. carburizing and are refined after heat treatment
step.
and Cooling
Gear lubricants perform a complex function of reducing friction, preventing destructive scoring at the sliding contact, and removing the heat generated by the tooth action. In order to minimize the weight charged against the lubrication system, the designs for large turbopump lubricant
at
gear the
trains incorporate minimum quantity
material
capabilities.
2.1.8.1
HEAT
The lubrication tooth friction
sophisticated required
flow systems that meter the most to maintain gear system temperatures
effective within
REMOVAL system must remove the heat generated losses, (2) windage and oil churning, and
in the transmission (3) bearing losses.
as a result of (1) The total of these
losses for spur gear trains is roughly 0.5 to 0.7 percent of the power transmitted per mesh. The largest loss occurs as a result of tooth friction except in very-high-speed gear trains where oil churning may absorb substantial power. Losses for rolling-contact bearings are generally much less than the associated gear losses. Methods for calculating gear loss based on theoretical considerations or on empirical results are given in reference 2 (ch. 14) and in reference
12.
Low gear
losses
• • • • •
can be achieved
by any
or all of the
following
actions:
Lowering the lubricant viscosity Carefully designing internal contours of the gear case to prevent Using helical gears; a theoretical advantage is cited in reference
oil trapping 2 (ch. 14, p. 6).
(Gear designers are not unanimous on this point, however.) Ensuring that more tooth load transfer occurs during the arc of recess the arc of approach (ref. 2, ch. 5, p. 18) Reducing the gearcase internal pressure to reduce windage.
22
than
during
2.1.8.2
SCORING
The
scoring
any
known (1)
resistance single Gear •
(2)
of a gear design
value.
The
design Contact
following
is affected factors
by many
are known
factors
and
is not
to affect
gear
scoring:
by
Sliding velocity Material
• •
Surface roughness Accuracy of tooth
surfaces
Lubricant properties • Flash temperature • Viscosity
(3)
Chemical surfaces)
Lubricant
activity
(extreme-pressure
compounds
react
chemically
with
tooth
scoring
resistance
based
on
variables
• •
Temperature Flowrate
• •
Method of application Cleanliness
V summarizes
the
various
scoring
indexes
that
predict
limited number of variables; also listed in the table are factors that probably resistance but have not been incorporated into any scoring index formula. indexes in descending order of apparent accuracy are (1)Bodensieck specific (ref. 13), (2) AGMA utilized only as a rough Reference
2.1.8.3
represented
stress
• •
•
Table
PREVENTION
16 presents
flash temperature estimate of scoring an evaluation
LUBRICANT
(ref. 14), and (3) PVT risk and is not considered
of various
scoring
a
affect scoring The scoring film thickness
(ref. 10, p. 53). PVT is a valid basis for design.
indexes.
PROPERTIES
Heavily loaded turbopump gear trains have been lubricated with petroleum-base oils, synthetic-base oils, and fuel-with-additive mixtures. Gaseous hydrogen has been used as a coolant in conjunction with dry-film lubricants applied to the gear teeth, and with a mist additive. Various propellants have been tested for load-carrying ability, but are not used as lubricants A summary
in operational of the
turbomachinery.
properties
of turbopump
gear
minimum operating temperature requirement search for low-temperature oil-type lubricants.
lubricants
is given
possesses insufficient scoring resistance for the Thor and Atlas gear was developed to fulfill both the Thor and Atlas high-tooth-load requirements; this lubricant tends to deteriorate in storage and must for scoring
1Appendix
resistance.
B presents
complete
titles
for material
specifications.
23
in table
of some vehicles (Thor, MIL-L-7808 oil I , used
VI. The
Atlas, Titan) in the Titan
-30 c F led to a engines,
trains. MIL-L-25336 oil and low-temperature be checked periodically
Table
V. -
Factors
Involved
in Various
Gear Scoring
Indexes
Scoring index Specific film thickness Scoring
factors a
(ref. 13)
Flash temp. (ref. 13)
PVT b (ref. 10)
Contact PV b
time
(ref. l 5)
X X
X
X
X
X
X
X
X X X
X
X X
X X
X X X
Surface roughness Gear accuracy
X X X
X X X
Initial temperature Material constant
X X
X X
Tooth load sharing Profile modification
X X
X X
Oil viscosity
X
Constant
load
Instantaneous Unit load
load
Rolling velocity Sliding velocity Entraining velocity Slide/roll ratio (specific Radii of curvature
X X
sliding)
of tooth
X
Conductivity
Tooth surface Waviness
X
topography
Lay Surface hardness Extreme-pressure property Density of lubricant
of lubricant
Specific heat of lubricant Coefficient of friction
X
X
Overloads (nature of application) Lubricant jet velocity aFactors marked with X enter into the calculation of the listed scoring index. bp ,, Hertz contact pressure, psi; V = sliding velocity, ft/sec; T = distance from pitch point to tip of tooth, in.
24
X
X
Table
VI.
-
Properties
of Turbopump
Gear
Lubricants
Lubricant
Property Viscosity, centistokes 210 ° F
Pour
°F
point,
value
Typical
MIDL-7808 Diester base Required
value
4
25 to 34 -
-40 ° F °F
base
-
100 ° F
Flash point,
I
Petroleum Required
Fuel-additive
MIL-L-25336
MIL-L-6086
Required
value
value
base
Hydrocarbon Typical
400
5
3 min.
4
11 min.
12
Pass
value
Typical
value
2 11
400 min.
450
-75
Pass
max.
a
compound
1500
430
-75
Pass
Required
value
17 1300
Pass
40
Typical
3 min. 11 rain.
30 30 500
280
value
Diester
mixture
110 -36
130 Pass
(freozing
point)
Load-carrying
capacity,
Ryder
gear test:
Load,
ppi
3 450 b
None
Test material --X MIL-L-6081
1700 rain.
140 to I60 b
100
76(2
1900 to 3100 b
76 to t30 b
tests)
to 5000 b
116 (2 tests)
l16to
100 b
Not defined
4000
to 6300 c
140 to 200 b
109 (6 tests) 107 (8 tests)
68 (8 tests) 50 d
40
2500
111 (4 tests)
72 (4 tests) 70(6 tests)
Load-carrying capacity, Shell four-ball tests
min.
2800
22 to 25 d
40 d
29 to 33 d
80 e
aILP-1 with 2 to 3 percent of Oronite 262 additive. bRocketdyne data; test: Federal Standard Test Method 791, method 6508.1 (see Appendix B for complete designation of this and other referenced test methodsl. CShell Research Colporation data. dRocketdyne data; test: Federal Standard Test Method 791, method 6503.2. epran & Whitney data; test: ASTM D-2596.
Maximum scoring resistance has been obtained with a mixture of RP-1 and Oronite 262, a zinc dialkyldithiophosphate additive (ref. 17). Turbopump proof-test runs are conducted with 10 percent by volume of the additive; in subsequent operation, the lubricant is RP-1 fuel mixed with 3-percent additive. The 10-percent-additive concentration used to "run in" the gears gives added scoring resistance in subsequent operation, apparently because of a residual extreme-pressure film. A heater blanket is used to maintain a relatively constant viscosity of the additive over the ambient temperature range expected and thus prevents excessive variations in additive concentration. The
RL10
turbopump
gears
successfully at approximately 15 800 ft/min PLV. Except
(AMS
6260)
250 ppi for the gear
are
cooled
by
hydrogen.
(pounds per inch of bore, which is chrome
These
gears
face width) face plated, a dry-film
operate
loading lubricant
at 1
is applied to the entire gear for lubrication of the active tooth contacting surfaces and for corrosion protection of the rest of the gear. The hydrogen is injected into the gear case as a liquid but probably performs its cooling function during vaporization and as a gas. Some rig testing has been conducted in which gears untreated with solid lubricants were run while submerged in various propellants (refs. 17 and 18). These tests showed that rocket engine propellants, although they may be good coolants, are poor gear lubricants and that the materials compatible with propellants are unsatisfactory for gears. High wear rates and extensive scoring occurred at face loads of 500 to 1000 ppi at a PLV of 10 000 ft/min with the fuels RP-1, liquid hydrogen, ethylene diamine, UDMH (unsymmetrical 1The
dry-film
AMS
3170
powder.
lubricant thinner
The
coating
consists as
of
required. thickness
The is
1 part
by
powder
specified
weight
of
consists to
be
0.5
of to
a powder 10
2.0
parts mils.
25
mixed by
weight
with of
3 parts molybdenum
by
weight disulfide
of
AMS and
3132 1 part
varnish of
with graphite
dimethylhydrazine), (inhibited has been
2.1.8.4
and
N 2 H 4 ; oxidizers
red fuming nitric acid), confined to low load and
LUBRICANT
DELIVERY
giving
similar
and N2 04 (ref. speed levels.
results
18).
were
As a result,
liquid
oxygen,
cooling
with
IRFNA propellant
SYSTEM
The Titan engine turbopumps use a recirculating oil system with a feed pump, scavenger pump, and heat exchanger. The single-pass systems used in lubrication systems for Thor, Atlas, and Saturn S-IB engines are operated by gas pressurization of the lubricant tank (Thor), positive displacement pump pressure (S-IB). In the
Titan,
disengaging side of the Further
Thor,
Atlas,
pumps
and
side of the mesh. mesh. The technical
discussion
Lubricant
of lubricant
delivery
(Atlas),
or a fuel-additive
S-IB systems,
the
blender
lubricant
spray
unit
streams
activated
are directed
Some designers prefer lubricant impingement rationale for the choice is summarized in the delivery
may
be found
in references
2 (ch.
Advantages
by fuel
to the
on the engaging table below.
15),
19, and
20.
Disadvantages
point Engaging side
Provides maxinmm elastohydrodynamic eration.
Disengaging side (preferred for high-speed gears)
potential for fihn gen-
Allows use of lower lubricant
Requires
pressure
flow.
Provides cooling at the point where gear tooth surface is hottest; heat is removed before it is conducted into gear mass.
Requires lubricant
Reduces tile possibility gear coolant trapping.
Some
gearbox
bearing
Trapping of oil between tips of teeth and roots of meshing teeth may result in surface erosion of teeth.
failures
have
been
tight control
of lubricant
careful targeting velocities.
and high
Most lubricant may be thrown before next mesh occurs.
off
of
associated
with
a change
in lubricant
circulation
caused by a progressive drop in gearbox internal pressure during flight. A concurrent increase in foaming of the lubricant also detracted from the cooling effectiveness of the lubricant. Remedial practice has been to (1) redesign the bearings, (2) use lubricants with low foaming tendencies, increasing windage.
or (3)
pressurize
the
26
gear
case
to improve
lubricant
circulation
by
2.1.9
Gear Case
To achieve rigidity and light weight, gear magnesium) castings with integral mounting loads arise from several sources: (1) (2)
Gear tangential External loads radial loads)
(3) (4) (5)
Loads arising from Internal pressure Thermally induced
Cryogenic pump flow and prevent heaters sometimes
driving reacted
and separating through the
the use of the loads
cases are made of light metal (aluminum or pads and .stiffening rings and ribs. The gear-case
(e.g.,
loads gear case
gear
from
(e.g.,
case as the
cryogenic
pump
and
turbopump
pumps
and
turbine
thrust
and
mounting hot
turbines)
volutes often are pin mounted to the gear ca_e (fig. 4) to minimize heat uneven chilling of the gear case and consequent misalignment. Electric are used to reduce the cooling influence of cryogenic propellants.
The gear cases for the turbopumps in early Atlas and Thor engines were made in two halves clamped together by bolts. The bearing bores were line bored with the gear case assembled, and relocation of gear-case halves was obtained with dowel pins. Although adequate for the original design loads, the split gear case did not posses sufficient rigidity tn maintain gear alignment under the higher loads accompanying subsequent uprating. The solution was to redesign
the
gear
case as one-piece
construction.
Gear-case design must include provisions that minimize or eliminate internal fasteners (nuts, bolts, screws, safety wire, and snap rings) that might loosen or back out because of vibration during operation. Joints in the gear case are clamped tightly enough so that friction prevents relative movement of the surfaces. Recessed static seals such as O-rings are used rather than gaskets, because gaskets allow relative motion of the flanges and require more fasteners tn prevent bowing and leakage between fastener locations. To confirm design calculations, an instrumented gear case is subjected to full design torque while dial indicatars, strain gauges, or brittle
lacquer
detect
deflections.
In the development of a design that will satisfy the fixed nominal center-distance requirements, the effects of thermal contraction resulting from differing materials or thermal gradients are accounted for so that negative or excessive backlash or tip interference does not occur. Changes in center distance are compensated for in design by providing sufficient tip clearance to avoid interference at minimum previously, involute gears tolerate moderate variations modifications such as crowning of the teeth (sec. 2.2.5.5) are shaft tilt resulting from distortions of the gear case. Gear allowable gear stress levels are decreased to allow for the effects 6).
27
center distance. As noted in center distance. Lead employed to accommodate load capacity is reduced or of misalignment (ref. 8, sec.
2.2 GEAR DETAIL Adequate
gear
strength
depends
on tooth
size, pressure
angle
(see
sketch
below),
number
of
Base
circle
teeth, and deflections
face of
width. Tooth profiles the teeth under load.
fatigue failures. Rim and excessive deflection from
often are modified Surface textures
web proportions tooth loads.
Although the gear system configuration gear dimension may be necessary to spacing, speed ratio, and minimum Nonstandard center distances results of detail design may sufficient strength; the design
2.2.1
are designed
often satisfy pinion
to compensate are specified to avoid
both
for expected elastic to avoid scoring and excessive
vibration
and
dictates gear diameter, some changes in this the combined requirements of component size to achieve adeauate tooth strength.
sometimes are used to achieve specific speed ratios. The indicate that a change of diameter is required to obtain procedure is then iterated until a satisfactory design emerges.
Pressure Angle
Relatively high (25 °) pressure angles are radius of curvature reduces contact stress tooth. High undercutting
pressure angles also (ref. 10, pp. 14-17).
permit
favored for turbopump gears because the larger and the wider base increases beam strength of the the
28
use
of
fewer
pinion
teeth
without
excessive
2.2.2 The
Number
number (1) (2) (3)
(4) (5)
of teeth The The The
of Teeth is chosen
to satisfy
maximum
Contact contact
conditions:
the gear system. In cases of resonance, changes are system components, or damping methods are employed The pinion teeth must not have excessive undercutting. Tooth contact must not result in excessive compressive if too few teeth are used.
allowable
costs; the practical and maximize life, factors exist.
2.2.3
following
speed ratio shall be that specified by system requirements. tooth size shall provide bending strength adequate for the design loads. frequency of tooth meshings must not coincide with natural frequencies
Iteration of the design analysis analysis of root bending stress (refs. 3, 8, and 11) is performed The
the
Contact ratio ratio
number
is required until all the above and face compressive stress for each turbopump gear. of
teeth
is a function
limit is regarded as approximately the number of teeth in pinion and
made to the gears (refs. 21 through stresses,
conditions based on
which
or other 23). will occur
are met. A detailed the AGMA methods
of manufacturing 100. gear
of
and
inspection
To ensure hunting-tooth action are selected so that no common
Ratio
can be visualized as the average contributes to a smooth transfer
number of teeth of load from one
in contact. tooth to the
A high (1.5) next (ref. 10,
p. 55). In the Mark 4 turbopump (Atlas sustainer), a stub-tooth design with low contact ratio was replaced with a full-depth design; the resulting increase in contact ratio contributed to a great improvement in life and reliability of the gear set. A low contact ratio increases the severity of dynamic loads and causes premature tooth breakage.
2.2.4
Face Width
Experience has shown the gear pitch diameter. near the ends of wider mounted diameter. circular
that width of a spur gear tooth should be limited to 0.5 to 0.7 times The accuracy of alignment required to prevent load concentration teeth is difficult to achieve. Some designers contend that accurately
and machined double A rule of thumb used
helical gears can by some designers
pitch.
29
have a total face width is to limit the face width
twice the pitch to six times the
2.2.5
Tooth
Involute
gear
dimensional gears
Proportions
tooth
(ref.
24)
of gear
proportions
given
achieve
such
and
Summaries
for
necessary.
terms
complete
abbreviations
the to
(Pd
systems standards
of
involute
are given and
spur
made
durability.
definitions
2 (ch.
for
helical
with
standardized involute
gears gears
and
spur
(ref.
5). Modifications
profile
sections
terms
in 19.99)
high-power
problems
following and
= 1 to and
These
to particular in the
specified (Pd
in reference are
used
in reference
proportions
coarse-pitch
>__ 20)
solutions
symbols
compilation
by for
generally
strength
achieve
and
is given
defined
standards
fine-pitch
tooth
made The
are
as the
proportion in
maximum
compromises a more
profiles
systems
25). to the
in order
modifications are
used
are illustrated corresponding
only in figure symbols
to are
when t0; and
1.
Working
depth
tooth thickness
/_/_Q_
_
d, dedendT_
_ addendum
Figure
10. -
Sketch tooth
2.2.5.1
WHOLE
Full-depth tooth action is obtained that
the
scoring The
smaller
illustrating
terms
and
symbols
for
proportions.
DEPTH forms with length
(ht
__ 2.00/Pa)are
the
resulting
of action
higher
preferred contact
on a stub
tooth
for turbopump gears ratio. Some designers, (ht
< 2.00]Pa)
represents
risk.
following
factors
are considered
in determining
3O
the
tooth
whole
depth:
because smoother however, believe a reduction
in
• Strength •
Contact
ratio
•
Maximum
• Grind
fillet
stock
• Addenda
proportioning
• Sliding
velocity
• Availability
2.2.5.2
TOOTH
Tooth
to avoid
2.2.5.3
tooth
standard
of the
to provide
of the important undercutting,
design
required
often
both
desired
calculations
made.
backlash
2.2.5.4
strength
ROOT radii
are
have
shown
radii,
enlarged
balanced
strength
is obtained
tooth
strength
If pinion
and
tooth
by thinning
backlash;
modifications
the gear
teeth.
and
must
be
2 and gears
10).
made
in the
Figure
addendum
of pinion equalize
of pinion with
tooth
(3)
to balancing
undercut
(refs.
gear
undercutting
teeth,
for spur
maximized
the
to reduce
importance (20X
with
of fillet
to 100×)
by the
TOOTH-FORM teeth
and
to
and
gear
and
(2) balance reducing
effort
pinion
teeth
teeth,
(thereby
is decreased
satisfy
the
the The
equal
sliding
addendum
values
the
bending
maximum)
all three
strength.
achieving
11 presents
from
of these addendum velocities
required
to
20 ° PA.
FILLET
also is controlled fillet radii chosen.
2.2.5.5
gear
give priority
avoiding
developed
Fillet
eliminate
and
designers
for
equal
is increased
A compromise
most
been
to (1) pinion
velocities.
objectives;
Gear
achieve
risk
be established
addendum
requirements obtain
and
of cutters.
proportions
strengths
have
scoring
undercut
ADDENDA
Pinion
sliding
and
must
it is one
are made
to avoid
THICKNESS
thickness
therefore,
radius
loads
compensate
for
errors
deflections.
The
goal
root-bending-stress radii
layouts
manufacturing
are
(ref. made
method;
26).
concentration. To
determine
of the
gear
the gear
tooth.
tool
Photoelastic the
maximum
studies allowable
The
allowable
fillet
size
manufacturer
must
review
the
MODIFICATION in excess of is
to
of 1000
ppi often
manufacture, achieve
are modified
mounting a
perfect
31
from
deflections
involute
profile
a pure
involute
form
to
under
load,
and
tooth
under
load,
and
tooth
Ii i
I '
For
addendum
with
other
use
1.40
_
"_ II
value
based
of
gears
pitches,
+ Pd
on
ht
=
"_d
1.30
to prevent undercutting
•_
chart
Chart
dimension diametral
_ _.
_
1.2o Addendum
required
\,...
A
___
o" _.Io ......
"_ <
1.00
0.90
i ..... -...........
0.80
0..70 10
12
11
13
14
15
Figure
of
11. - Addenda teeth
modification
usually
Methods
for
concentrations
near
corrections making
(axial them
crowning may
the
ends
from
easing
is maintained,
reduction
of gear
load
modifications
torsional
windup
are used
to correct
being
of tip relief
teeth
30
40
60
vs number
of gear
80
125
considered
or a combination
that
in.
by
consist
of
near
on the
to 0.002
are
caused
thinner
crowning
the
design (ref.
greater
misalignment crowning
ends
loads
2, ch. than
of tip
presented
and 5).
0.0006
or
than
and
in
reference
are
minimized
end
in the
easing center).
expected
flank with
the
teeth
The
amount
misalignment.
In high-precision in. is avoided
relief.
27.
lead (i.e., of
Crowning
gears
where
because
Load
it results
good in a
capacity. also
on
25
gear
modifications
of
depends
0.0005
on
values for equal strength
form
modifications)
alignment
Lead
the
teeth
(20 ° PA spur gears).
required
circumferentially
or end
range
takes
calculating
20
17
Number
gears
scoring
are
used
with noted
face
to provide widths
in service
more
of 1 inch and
32
therefore
even
load
or more.
distribution Lead
are based
on
modifications on experience.
teeth
with
generally
2.2.5.6
SURFACE
TOLERANCES
Since
it is not
possible
axial
surfaces
(lead
dependent
on
application. sample
the
The gear
to produce profiles) gear
load,
allowable
a perfect
gear
allowed
to
are
speed,
and
deviations
inspection
charts.
Lead
profile
Involute profile surface texture
defined
and
and
surface, from
smoothness
are
Lead
tooth deviate on
involute
surface
tooth the
of the
involute
nominal
operation gear
surfaces
an
12)
by
which are
and
amount
required
drawing,
(fig.
profiles
by
the
includes
translated
by
texture
and
Tip
Hub
Root
Figure 12. - Sketch illustrating
terms for gear surfaces.
inspection machines to lines traced onto chart chart translates an involute curve to a straight from
a
perfect
profile tooth
or lead traces
restrictions that
involute
the
modifications are
determined
by
pitch
range
in the
on
of reversal the
readily
observed.
are reproduced
required
placed rate
are
to fall
the
involute (change
severity
of
within and
Desired on
the lead
the
of the
The
8 to 12 are as follows:
33
normal
profile
sample
tolerance
profiles
in direction service.
paper from the actual line, so that deviations
surface limits
tolerance
inspection
band
are that
gear tooth. The rolloff of the tooth surface
to
be
they for
charts not
should
power
gears
including
(fig.
acceptable.
should
trace)
bands
13); gear
Additional
be concave
not
exceed with
and a rate
diametral
-- Flank
r Db
(base
I
i
circl e)
I 4o F4 O
modification
Tip
TIF
I
D
(pitch
modification--
circle)
D o
I
I
• 003 • 002 • 001 .f.
'iL
• 001
/'//
©
O +O
.002 .003
_Tooth
_Degrees
roll
(a)
Involute
Limits
profile
from
base
rolloff
must
fall
within
these
limits
circle
chart
Tooth
_i_
Flat
potion
for
modified
profile
centerline of
tooth_
I
t'-
° f
i
Ill
I
/ii
! i
t'_ tl/
t t.t
°
.,-I > ©
t
Face
width
Face
,,
!
(b) Lead
width
-
chart,
crowned
FigUre
13. -
(c)
tooth
Sample
inspection
34
charts
for
Lead
chart,
involute
and
end-eased
lead.
tooth
|
Allowable Type of gear Main power (heavy loads)
0.0002
Accessory
0.0003
loaded
2.2.5.7
SURFACE
The
surface
gears
and
textures average)
satisfactory
service coarser
used,
but
limited
exceed
50
power
of both are
(arithmetic and
to 20 and
gin.
are
and
AA
within tend
testing When
active
carefully
finishes
gin.
peak-to-peak
and lightly
TEXTURE
therefore
finer
rate of reversal, in.
for any 25% of active profile
surfaces
greatly
design.
Roughness
for gear
tooth
contact
surfaces
the
indicates
production and
that
are
the
waviness
range
gear
by
to score
defined,
frequency
nonactive
controlled
capability avoided.
surface
been
limits
will
control
roughness
and
the life
of 6 gin. found
are
Both
not
height surface
of AA
to give
manufacturers.
peak-to-valley
specifications
between
have
of gear
Waviness
maximum
influence values
presently should
quality
the
rate
of
ends,
and
roots)
not in the
reversal
requirements. The
surface
effect
on
examples over
onto
have
roughness Other
gears
during
a
of noncontacting
fatigue of
maintaining Tests
quality
life.
active
Oronite
shown
that
ensure
that
the
a surface
roughness
process.
Scoring
than
marks
on
Reference
28
262)
lubricant,
oils. gear of surface design
Shot
lands,
tooth
and
gouging
lands
and
in the
tooth
discusses
but
texture goals
has
changes
increased
the
been
mixed vapor resulted
on noted
root
ends
has an fillet
are
not
lap
effects
of
must
beneficial
have
in marked usually
35
smoothed with
been or
operation.
12 gin.
AA out
roughness
in operation
blasting,
are achieved.
AA
gears
results
measurements
during
to 10 to
of 26 to 32/ain. occurred
has
peening,
surfaces
roughness
4 /_in. AA
improvement
the
webs,
tempering,
Similar
surface
with
noncontacting
surface
surface.
of less
run-in
(rims,
integrity.
values
diester-based Directions
marks,
conditions.
contacting
surface
Surface-roughness 2%
Tool
detrimental
areas
with
improvement are specified
grind
with
operation.
to 10 to 14 gin. over
32
fuel-additive
obtained
special
Surfaces during
with
AA.
(RP-1
plus
petroleum
control in gear
on the drawing
of life
AA
gin.
and critical
(ref. (fig.
28). 12) to
2.2.6
Rim and Web
Rim
web
and
designs
often
are dictated
by the
operating
vibration
spectrum.
Thin
webs (< ht)in particular are prone to vibration problems. Large radii are used to webs and webs to hubs to reduce vibration-caused fatigue failures of the frequencies
coinciding
web
mass
shape,
of rims
and
problem web
webs
that (fig.
operating and
sometimes
occurred
thickness,
surfaces
with
distribution,
forcing
is effective
on uprating
increasing
rim
frequencies
size, number,
and
in preventing
of the Mark
cross
section
3 gear and
are
shape
blend
avoided
by
of lightening
web train
fatigue was
radius,
altering
holes.
failures.
eliminated and
shot
rims
rim
peening
A web
fatigue
peening
the
14).
Whole in.
thickness-_
_'-
0.19
in.
radius
0.5
in.
radius
depth
-'---"
F
0.217
_
_
in.
F0.298
0.5
in.
radius
0.5
in. radius
I
I_
I
I
.
Shot I peen
I I
I
Web thickness
_
la)
Original
0,250
in.
(b)
design
Uprated
design
Figure 14 - Sketches illustrating rim and web dimensions (original and uprated designs)
36
and
Shot
by increasing
Rim
and
to blend rims web. Natural
the web
On
highly
stressed
power
adequate
power
resonant
frequencies.
proportion
tooth
between
the
changed Rims
capacity
manufacturing are
The
ease loaded
not
too
of the
thin.
natural
low
Normal
also
are
and
with
the
holes
often
and
to avoid
are given
as a
a weakness.
to a resonant The
normally
are placed spokes
dimension
achieve
For
condition
wheel
contour
was
was eliminated.
levels
the
to
are sized
indicates
traced
problem
that
web
frequency.
stress
to ensure
and
experience
were
mesh
low
circumferential
can be estimated
determined (ref.
diagrams
determine
on
minimized
if testing
gears
the
Lightening
of gears
resonances
Interference
based
are made
and
those
is taken
spoke
are
Rim
are
are sized
to achieve
in the webs
between
is from
of low-cost
the lightening
0.5
holes
to 115 times
the
size
holes.
frequencies
frequencies
and
dimensions weight.
II idler
frequency,
cost.
Care
usually
in Titan
natural
web
Changes
frequency
gears
and
gears.
lightening
observing
wheel
and
at minimum
depth.
natural
of small
rim
proportions failures
wheel the
the
stiffness
whole
breakage
webs
or lightly
tooth
gear
to alter and
and
The
of the
example,
gears,
whether
any
experimentally
21).
(also
by analytical
Sand
called
by
modal-shape
shaking
or "popcorn"
Campbell
methods, simulated
salt I is used
diagrams)
standing-wave
are
or
for
the
normally
actual
to reveal
plotted
frequencies
but
gears
mode
with
made
as large
and
patterns.
various
coincide
the
modes
gear
to
meshing
frequency.
2.2.7
Tolerances
As
of
part
the
consistent
effort
with
the
suitable
for
requires
tolerances
engine
different
modified summarized will
result
requires
power
class 10 in table in close
a
The
accuracy
than
the
the
limits
Ipopcorn evidence
liaison
and
and
require meet
which
with
gear used
chloride
that
frequencies
tolerances
The
entire
of AGMA tighter
class
limits,
cost.
coordination
established
spectrum than
Achieving
classes
aerospace
gears
14. In general,
other
aerospace
accessory
capabilities below the
as possible
tolerance
of current
9 through
while
manufacturing of the tolerances in
has
classes
tolerances
13
are
AGMA
rocket
power
gears
are
gears.
made
to meet tolerances values shown in the
the
levels
of measuring-instrument
of
accuracy
calibration
to are table
shown between
user. dimensions
tolerance,
of equipment is sodium
special
costs,
4). The
increase
the gear
manufacturing
salt
gears
limits. Present VII. Reduction
with
of vibrations
(ref.
gears
corresponding
the manufacturer
gear
reliability.
are a combination
power
turbopump
down
gear
applications that
turbopump
Most
to hold required
although
can
this ratio
for measuring is finer higher
than
table
than those
be measured
gears salt but that
37
is not
produced coarser
than
can be seen with
should always
be a factor achieved.
in quantity talc. sand.
The
smaller
of
Table
10 finer VIII
in production grain
size provides
lists runs, visual
Table
VII.
-
Gear
Manufacturing
Tolerances
on tooth
Tolerances
elements Finishing
Dimension
Hobbing
Involute Lead,
in./in.
Tooth-to-tooth
spacing
Whole depth Fillet radii Circular tooth Out-of-roundness
thickness
Concentricity Surface roughness,
gin. AA
Tolerances
Shaping
Journal Bore
concentricity concentricity
Journal-to-bore Tooth
element
concentricity concentricity
Grinding
5
3 15
3
2
15
15
30
30
30
5
5O
5O
5O
30
30
5
25
25
30 25
10 15 10
10
25
25
20
5
5
125
63
32
16
20
on gear body
3
2 5to
2
1
1
10
5+
elements
Grinding
method Grinding
and polishing
5
1
1
5
1
1
10
2
2
10
2
2
15
2
2
20
10
10
Taper Parallelism
5
1
1
20
2
2
Hub dimensions
20
1
Web dimensions
20
5
1 5
Rim dimensions
20
2
2
Fillet
50
lff
63
16
10 4
Surface
dimensions roughness,/ain.
AA
aExcept as noted, tolerances in this table represent ten-thousandth inch (2 = 0.0002 in.). bHighly specialized gear configurations for production measurement accuracy. 75 percent.
Honing
5
Machining
Journal diameter Bore diameter
method
Shaving
Finishing Dimension
a ,b
total ranges and are expressed in units of one
can be produced for specific applications to tighter valtles Rejection rate in this specialized field is seldom less than
CTolerances for honing are for corrective machining of values in excess of table values. Honing is not recommended for hardened rocket engine gears because of resultant surface texture.
38
c
Table
VIII.
-
Accuracy to Inspect
of Measuring Production
Equipment Runs
Used
of Gears a
Tooth elements Dimension
Measurement 1 0.5 1 0.5
Involute Lead (axial),
in./inl
Lead (helical), in./in. Tooth-to-tooth spacing Accumulative pitch Whole depth Fillet radii Pitch diameter Out-of-roundness Concentricity Surface roughness,/_in.
accuracy
1 5 10 2 2 2 (linear surface) 4 (curved surface)
AA
Gear body elements Dimension
Measurement 0.5 0.5 1 1 1.5
Journal diameter Bore diameter Journal concentricity Bore concentricity Journal-to-bore concentricity Tooth element concentricity
5 0.5 1 2 2 2
Taper Parallelism Hub dimensions Web dimensions Rim dimensions Fillet dimensions Surface
aExcept pressed
2
roughness,/aim
as noted, in units
accuracy
values
2 (linear surface) 4 (curved surface)
AA
in this table
represent
of one ten-thousandth
total
ranges
inch (2 -- 0.0002
39
in.).
and are ex-
•
_)
,.
Table
IX. -
Accuracy of Metrology Laboratory Measurements on Gears a
.-
Tooth elements Dimension
Measurement
accuracy
:7 i0:i1: b:i :•
Involute Lead, in./in. Tooth-to-tooth
spacing
Accumulative pitch space Whole depth Fillet radii Pitch diameter
0.1 0.I 1.0 1.0
Out-of-roundness
1.0 1.0
Concentricity Surface roughness,
_tin. AA
2 (linear surface) 4 (curved surface)
Gear body elements Dimension
Measurement
Journal and bore diameter, taper, roundness
0.05
Concentricities
0.1
and nor-
malities of journals, and tooth elements
accuracy
•
bores,
?
•
Hub, rim, web dimensions Fillet dimensions Surface
aTable formed calibrate
roughness,/aim
lists the accuracy on gear elements• production
ten-thousandth
AA
2 (linear surface ) 4 (curved surface)
of measurement
(in inches)
These
measurements
measurement
equipment.
inch (2 -- 0.0002
in.) unless
40
that
are used
can be perprimarily
Units
shown
otherwise
noted.
to
are one
.,.-
while The
table
IX presents
laboratory
2.3
the
equipment
limits
achievable
is used
in the
primarily
most
specialized
metrology
to calibrate
production
measuring
equipment.
MATERIALS
2.3.1
Gears
The
materials
gear
practice
used
in turbopump
with
some
gear materials suitable the basis of chemical A summary
of the
gear
additional
systems
materials
used
are
refinements.
for lubrication by rocket compatibility rather than
Table
Materials
gears
to those
attempts
propellants; strength and
in turbopump
X. -
similar
Some
Application Critical,
highly
loaded
Gear matirial i _ower gears
AMS
265
in table
Moderately
loaded
gears
AMS
260
dlL-L-6086
oil
Used where
oil
are required;
Same
oil
;20
AMS
470
Propellant-cooled or lightly
gears
gears, moderloaded
Lhe
above, AISI
dus 340
AISI
140
AMS
;260
AMS
;265
AISI
.40C
copper (Berylco
aRP-1 plus Oronite 262 (2 to 3% concentration
tm
Used for accessory
LH2,
LO2, RP-1
Gear material corrosion
Gear material
N204
corrosion
diamine, LH4,
GH2
in service, up to 10% during run-ins).
41
than
must have
from
gears.
must be protected
from
by moisture.
LH2, LO2, IRFNA,
Ethylene
re-
to avoid edge
must have protection corrosion.
as above
UDMH, N_H4, 25)
less critical
edge radii
Same
status
Bery
and reliability
protection
Used for wear resistance; smooth
Any
corrosion
Used in applications those above.
as above
chipping; moisture
loaded
high capacity
a
(nitrided)
-Lightly
Xi
quired.
AISI 9310 AI5 ;20 AISI
aircraft to select
Comments
MIL-L-7808 Fuel-additive
for made
Gears
Lubricant/coolant
MIL-L-25336
been
these materials were selected flare very limited usefulness.
is presented
for Turbopump
developed
have
i _1
ately
laboratories.
very brittle;
resistance;
has some
in experimental
only.
Gear material
low in hardness;
herent corrosion mental status.
resistance;
has in-
in experi-
on
Deep-carburizedcase-hardenedsteelssimilar to vacuum-meltedAISI 9310 (AMS 6265) have been found to possessthe best combination of properties for power gears;the hardened outer surface resists compressivestress and wear, while the tough ductile core provides resistance to shock loads and has good resistance to bending-stresscycle fatigue. Use of vacuum-meltedsteelhasextended the fatigue life of gears. The useof corrosion-resistantmaterials for gearshas beenlimited to experimental programs, because no corrosion-resistant material possessesthe combination of hardenability and toughnessrequired for highly loaded power gears.The 300-seriessteels and the Inconels cannot be sufficiently hardened to withstand high compressivestresses;in addition, these materials tend to score and gall excessively.The truly hardenable stainlesssteels,such as 440C, are too brittle to withstand dynamic tooth loads. Beryllium-copper alloy carl be heat treated to approximate the tensile strength attained in the core of carburized steel gears,but the surface cannot be hardened to withstand the compressivestressesencountered in power gears.The lower modulus of beryllium-copper alloy allows greater bending deflections but at the same time reduces the peak stresses causedby dynamic loads. In one experimental program (ref. 18), nitrided 410 CRES was tested as a candidate gear material that would combine corrosion resistance,a hardened surface, and a ductile core. Although the gearswere superior ro 440C gears,the extremely brittle hard casechipped at the tooth corners.
2.3.1.1
To
MATERIAL
obtain
many
the
details
GRADES
load
capacity
of
the
carburizing
steels
AGMA
recognized
has
vary
and
reliability
manufacturing over the
a wide need
1 (minimum
quality
are acceptable.
Grade
2 (normal
Rigid inspection quality is in fact
quality).This
the
for
Process
control for aircraft
All
material
properties
be and
gear
on
accessory
two
tight;
heat
lots and
properties specified.
grades
of The
are defined
been
defined,
small
deficiencies
and
a
in
gears.
required
control (aircraft quality) guarantee grade is used in aircraft power gears.
42
The
have
is moderately
steel
the grade
processes;
materials
are
gears,
specified.
depending
materials
aerospace
is used
quality).-
must
extent
grade
and process achieved. This
for turbopump
processes range,
for grading
in reference 3. Three grade levels fourth appears potentially useful: Grade
required
to
meet
that
the
high
standards.
specified
high
Grade
3 (premium
can
presently
and are
process tested
provide
no
power
expense
is spared
of parts,
2.3.1.2
to
mill
achieve
lot
the
control
are employed.
achieved
gear. The is allowed
strength,
composition
bought
in registered
Compliance
it is expensive randomly of steels
that
gear
to achieve.
chosen parts is specified.
manufacturers
Rigid
inspection
out of production runs This grade is used in
can be manufactured
optimum.
of the
Reduction
case and
core
hardenability and
steel,
Rigid
laboratory
process
analysis,
in cost
will follow
are major
factors
a representative
the
by present
technology;
inspection
and
and
more
in the
of the
of AMS
random
widespread
process
destructive use.
strength
and
durability
of a
a vacuum-melted
(H-band)
is based
on end-quench
Alloy
carbide
banding
solution because
temperature required. Vacuum remelting of the smaller mass of a vacuum-melted
2.3.2
Gear Case
Gear-case
often
materials
The
compatible
with
(such
as
are included
are
materials
chosen
must the
of
coefficient
of thermal
light
be strong,
weight
power
low-alloy
to
the
gears
are
carburized
is documented
and
hardness-traverse
steel.
certified tests
by
made
on
fabricated,
environment. Tens-50)
is
considered (sec.
to
2.1.9).
43
used
rigid
hot
soaking because
structure
dimensionally
Lightweight, are
by
to this process
to induce of the high
specifications.
a lightweight,
easily
reduced
has a beneficial effect in reducing banding ingot. Requirements intended to reduce or
in gear material
or
expansion
been
is not amenable
to provide
service
A356-T61
advantage
banding
has
of alloy
banding
in addition
into nearly parallel bands aligned in the direction on material properties and thus is considered
solution
eliminate
limits
specified
for turbopump
lot of steel.
materials.
bands;
are
Materials
6265,
of alloy constituents has unknown effects
in gear
(H-bands)
requirements.
hardenability
certification
sample
Banding (segregation of metal working) undesirable
lots
specified
producer;
tolerances
cleanliness
mill
to the
steel
alloys
aircraft-quality
hardenability is dependent partly on the chemical composition of the steel, which to vary within limits specified by the material designation. To ensure attainment
adequate
gears.
that
PROPERTIES
in the
material
the
grade
quantities;
- Best material
METALLURGICAL
Hardnesses
of
material
in production
quality).
including
testing
Best
gears.
4 (ultimate
control,
-
control are required. In addition, destructively. Use of mill lots
turbopump Grade
quality).
for
outweigh
stable,
high-strength most the
for
turbopump disadvantages
mounting and
castable gear of
the
chemically aluminum cases. the
The larger
Magnesiumalloy has been used for to avoid
electrolytic
also has been
2.4
a problem
of the
therefore
with
fabrication
must
to maintain
magnesium
2.4.1
by alumimun steel inserts
gear cases.
be considered
are
designed, forging
gear
For
maximum
High-energy-rate webs, to the
rims,
desirable
material
responsibility.
as forging
flow tooth
from
and
gear,
forged
bar stock.
but
the
outer
after
peening;
their
properties
It is especially
shot
effects
these
and
important
processes
cannot
the
hubs.
has
Tests
of the
dies.
have
be verified
by
approximates
been
used
to forge
run
on these
around
gears
the
by gear rolling
and the
gear-tooth-root
teeth
are
of the blanks
increased fillet
used
are made
is made
(refs.
a
than
cut
in the
finished
gear
including
gear
strength
to improve
in
from
in all dimensions the
gear
shown
also has been
gear
outline
complete have
orientation;
gear forgings
to 1/4 in. larger
flow
grain
A typical
is removed
grain
metal
forming
1/16
stock
to improve
power
forging
is made excess
in order
turbopump
closed
shape
forging,
blanks
Most
dimensioned
forging
and
grain
31 ). Plastic-flow
from
strength,
teeth,
2.4.2
made
shape;
shape.
17, 29, grain
and
life
30,
and
flow.
Tooth Cutting
teeth
are
carburized,
cut
obtained
by
to obtain
in a blank
hardened,
hobbing gear teeth machining methods
cutting
to attain
designer's
such
of the
are made
accurately
in which
finished
pitch
of the
performance
gears
gears
specially
Gear
part
of processes
on the testing.
turbopump
noncritical
blank.
is necessary
Forging
Critical
blank
processes
consistency
great influence nondestructive
due
gear cases but generally has been replaced consequent corrosion. Retention of threaded
and
FABRICATION
Control
the
action
and
diameter. a range
hobbing, It
shaping,
is easier
than by other means, but must be carried out with
hobbing.
the
by
finished.
Short-pitch
maximum These
undercut hobs
of number
on gear tooling design. specialized tooling.
must of teeth,
Gear
tool
hobs
or
to
fillet
be
designed
radii
often
44
used
while for
as are standard suppliers
grinding
a superior
a specific hobs.
in preshave
providing Reference
can furnish
capable
the
is required. the surface grinding
and
are not
10 presents consultation
gear
texture
and pregrind
some gear
before surface
more axial cutter clearance additional care to achieve
are sometimes
and
green
obtain
is by
Other texture cutting
stock
at the
suitable
for
information as well as
Shapingof gearteeth is usedprimarily when gearsand splinesare in axial proximity to other components. Shaping generally does not generateas smooth a finished root ashobbing and therefore is the secondchoice of tooth-cutting methods. Grinding in place of a cutting operation often is called."green grinding." Greengrinding of tooth forms from solid blanks is possible when gearsfiner than 20 pitch aremade; coarser pitch gearsgenerally require some type of pregrind cutting operation. Green grinding of complete gear forms has some advantages;it is used to obtain a slightly better texture, especially on hard materials, and may be required for materials that work harden. Green grinding is not usedin producing turbopump power gears.
2.4.3
Heat Treatment
Power
gears
are
Carburization environment; Critical conditions
of
time,
into
content.
heat
carburizing
and
2.4.4
Most
gears
thereby
shaft.
Generation
roots removed
are
the
only
grinding
to obtain
roots
ground, from
brittle
case.
the
to
also
wear-resistant
has
atmosphere
a desired the
in
that
are
potential
for
by nitriding
it is more been
gradient
of areas of
be obtained
not
32.
controlled
carburizing-medium
because but
teeth.
in reference rigidly
carburization
may
the
carburizing
obtain
surface,
Nitriding
given
and
of
is avoided
hardening
are
under
to prevent
copper
Case
finished Form
requiring
is used are
is used
the
a superior
the
a small
used
the
expensive for
than
turbopump
critical
grinding
in order
has the
amount with
to obtain
advantage
of axial
larger
clearance
wheels
the
of permitting and
between requires
best the
texture
parts
more
and
use of a small on
the gear
generous
axial
clearance. the required
of accessory care
by
grinding
is done
to give grinding-wheel
addition,
materials, is used
of
high-temperature
Finishing
to tolerances.
wheel,
Grinding
AGMA
concentration often
durability
carbon-rich
gears.
turbopump
spacing
embrittlement.
by
a
furnace-wall
frequently of
surface
to
carburization
cycle
in a more
the
parts
gas-type
carbon
stripping
results
Tooth
conformance
plating
produces
main-power-train
to
heat-treatment
Acid
process
the
increase the
recommended
subjected in
Copper
hydrogen
This
to
exposing
temperature,
the
treated.
introducing gears.
are
Variation
programmed
carburized by
procedures
gears
composition.
not
case
obtained
carburizing
power
carbon
deep
is
must area
and be
accuracy lightly
taken
of the
root.
to
of all critical
loaded
power
ensure
that
Sometimes
45
contacting
gears
generally
a minimum only
the
profile
sides
surfaces.
are ground.
of hardened of noncritical
In
When stock gears
is are
ground, and a greater blending tolerance may be made between the heavily loaded avoid removal by grinding
The due
in the
ppi) case,
roots;
grinding
Residual
tensile
stress
this area
is loaded
section. service
(above 2000 of hardened
turbopump gears, unground as it is difficult to determine also induces on
factors
contribute
gear
size,
induced
in the
to gear gear
The
parts
then
quenching limit
on
areas
(zone
than
gear the
may
fillet,
zone
residual
roots
Grinding
not
Shot
are
that
the heat
undesirable
may
be
in the root
desirable,
defined
that
the
loaded cause
heat
on
flow
produces
entire but
depth
ground;
surface no
since
in
this
the
is cleaned. steps
area
on accessory
may
(fig.
hubs).
sometimes
to 0.005
in., the
approximately
15).
The
gear
conforms
B, between risers
from not
and
20
grinding.
surface
Zone
or stress
is protected gears
is made
is
by carburizing
(webs
distortion;
for finish
factors stresses
generally
gears
only
to 0.003
gears
These
Distortion
areas
entire
contacting
unrelieved
in large
depth
hardened
of the
and
minimum
to allow
that
sharp
hardening.
is controlled case
critical
and
is reduced nonhardened
to ensure
percent
treatment.
from
"as-carburized"
completely
100
technique,
Distortion
"as-finished"
Grinding
of lightly
abuses
The
is not
stresses.
of wheel grit, coolants, burns on finished gears.
2.4.5
size.
that
carburizing
Distortion
carbon
purpose.
be ground;
C, normally
tensile
in the
and
or may
this
ensure
preceding
width. the
desired
of grinding
dimensions
root,
face so that
for
A, fig. 15) is ground
design
For
are specified in order to amount of case removed
stress
surface
heat-treating
processes
and
to
during
design,
removing
are used
deeper
Three
distortion
are quenched
dies
depending
percent
size
and
is allowed
forging
manufacturing
the
complete
to
shape,
proportional
profile
roots.
for grinding stock depends on the amount of distortion of the gear heat treatment. Ideally, the minimum amount of case should be
removed. Enough grinding stock surface of each tooth is finished.
include
tooth
tensile
and
in compression.
required allowance to processing and
Many
a gear
a residual
roots the
profiles
the
profile
and
The
root
are allowable.
grinding
be critical
and
profile
to required
the
and may
resulting
be allowed
gears. retempering
feeds,
and
and speeds.
rehardening
Nital-etch
can be avoided
inspection
is used
by proper to check
selection
for grinding
Shot Peening
peening
increases of shot peening
of
tooth
surfaces
130 to 400 percent terms and processing
and
other
gear
surfaces
have been in detail.
noted
(refs.
46
extends 33
and
gear 34).
tooth
Reference
fatigue
life;
34 defines
_
Outside
diameter
\
\ Zero
/
blend
Zone
/ / /
Zone (grinding
lines
B
(transfer from profil e to fillet; grinding and honing may or may not be present)
A
or honing)
/
\ \
/ Specified fillet radius
-_
Zone
B
Zone
C
Contact
/----"No
Blend
radius
(both tions
configuraacceptable)
diameter
grind"
diameter Point
(no grinding
of
or honing)
of
Blend tangency
tangency I_
/-_Root
Figure 15. --Sketch illustrating hardened gears.
The root fillets of gears are peened the effects of surface discontinuities
Gear rims and in tool marks,
webs nicks,
of critical and other
Shot the
peening surface.
is known Shot
to retard
peening
before
grinding zones on critical
to increase the of the teeth.
residual
gears are shot peened surface imperfections
significant increase in the average fatigue to the effects of shot peening the web.
plating
helps
cracking prevent
compressive
to prevent that may
life of the Mark
stress-corrosion
diameter
by reducing plating
47
and
to reduce
fatigue cracks from forming occur during manufacture. A
3 gear train
the base material; however, it is not a substitute for reducing baking the part. Multiple peening the same part with different-size
stress
cracks
was attributed
the from
tensile
in part
stress
extending
on into
embrittlement potential by shot has further increased
fatigue
life
creates
a very
under exhibited steel
The
by
shot.
effectiveness
size
that
Corrosion when
appears
to
depends
on and
or
and
failures
fretting
steel
of
preparation are
the
surface
of
before
detrimental
have
cast
performance
the
have
parts
non-corrosion-resistant
lubrication
a gear
to
stainless
greatly.
on
peening
shear
resistance
is not increased
scale
intense
subsurface
Some
with the
extremely
reduce
glass.
peened
improve
roughness
that
will
resistance
steel
resistance
oxidation,
indication
stress
stainless
surface
indirect
test
strip
method (a
thicknesses) holding
an effect gears
is used
piece
of
on
the
indicating
the peened
to the
required
subjected
For
achieve
achieve
the
and
iron active
peening.
are
removed
necessary
•
A data
•
Sample involute with limits
•
Sample
•
Rootfillet
design
turbopump
gears,
of
time 98
long,
work
a peening
in one
of
When to the
for
released
surface.
standard from
the
compressive
of 0.015A
--.001
It is expressed the
An Almen
three
residual
callout
= 0.051
is specified. of
treatment.
piece.
in height
(thickness
percent
controlled
is used,
in.). as multiple
Turbopump
of the gears
are
Control
of gear
include
three-view
document
3 in.
as the
in. for an A strip
control
A detailed
quality-control
wide,
peening
is therefore
of a shot-peening
an arc proportional
indenting
that
•
lead
in.
and
MIL-S-13165.
of 4N:
to specifications
block
effectiveness
an exposure
Configuration
or refers
effectiveness
specification
3/4
same into
of 0.015
to an exposure
2.4.6
the
arc height,
to
steel
bows
side.
an arc height
In addition
to gage the
to
strip
on peening
by invoking
spring
is exposed
fixture,
stress
has
of turbopump
An
to
33).
with
peening
uniformity
processing
This
of
is some
peening.
Shot
To
the
decarburization,
before
(ref.
peening
that
There
compressive
corrosion
Light
provided
Minute
36).
peening
decreased
surfaces
and residual
stresses
increased
time
35
deep
compressive
been or
(refs.
drawing
(see table
(figs. (fig.
is essential personnel.
physical following of the
characteristics,
the
gear
drawing
of roll from
base
circle
includes
items:
gear
XI for an example)
roll-off
chart detail
the
chart 13(b)
based and
on degrees
(fig.
13(a))
13(c))
15) in conveying Reference
the 2
requirements.
48
(ch.
designer's 11)
intent
discusses
to the gear
manufacturer
drawings
and
and data
Table
XI. -
Sample
Data Block
for Gear
Drawing
Turbopump gear dimensions (representative values) Tooth
element requirements
Power gears
Number of teeth
33 11 25 3.000 ref. a
Diametral pitch, in.- 1 Pressure angle, deg Pitch diameter, in. Involute form (profile) Base circle diameter, in. Outside diameter, in. Root diameter, in. True involute form (TIF) diameter, in. Fillet radius, in. Addendum, in. Whole depth, in. Circular thickness at pitch diameter, in. Measuring pin diameter b , in. Measurement over pins b , in. Maximum involute profile error c, in. Maximum cumulative pitch error (any two nonadjacent Lead error, in. per in. of face width Tooth-to-tooth spacing error, in. Crown, in. Rate of reversal, inches in any 25 percent Backlash when assembled, in. a"ref."
means
dimension
bThese
values
may be established
CAll gear values
2.5
2.5.1
for reference
+0.000
5.966 -o.oos 5.664 ref. 5.720 max. 0.025 min. 0.0667 ref. 0.150 max. 0.1269 ref. 0.14400 ref. 6 ,_,_+o.ooo
.,_,-ti -0.002
2.803 ref. 2.890 max. 0.028 min. 0.1205 ref. 0.219 max. 0.1650 - 0.1677 0.17454 ref. 3.3117 - 3.3167 teeth)
.u_-_.O.O06
+0.0003 (see chart) 0.0015 0.0003 0.0003 None 0.0003 0.006 - 0.010
(see chart)
0.0002 (see chart) 0.0002 0.0002 (see chart) 0.0002 0.003 - 0.007
only.
by the quality
from
70 12 20 5.833 ref. standard 5.48152 ref.
modified 2.71892 3 -_1+o.ooo
+0.0002 0.0010
gears
assurance
the axis of the part
department
and may not be included
as designated
or from an axis determined
in the gear drawing. by its mounting
diameters.
TESTING
Acceptance
Quality-assurance severity
given
are measured
Accessory
of
tests service,
Testing
for the
gear
acceptance
reliability
depend
required,
49
and
on
the the
gear service
property history
considered, of
the
the gear.
Quality-assurance 100-percent
requirements inspection,
(1)
All gears
for
sampling
inspection,
are subjected
• Dimensional
turbopump
to the
check
• Magnetic
of case and
particle
• Surface Heat-treat
etch
as summarized
of
below:
texture
cracks
magnification
gears
and
flaws
if required)
presence
or sample
a combination
core
for
to determine
specimens
are
checks: surface
exposed
inspection
gears
certification
including
• Visual inspection (with other surface flaws (2)
and
following
inspection
• Hardness
main-power
of surface are
for nicks,
tempering
tested
tool
from
destructively
marks,
grinding
for
the
and abuse
following
metallurgical properties: • Case hardness • Core
hardness
• Chemical
composition
• Case depth • Microstructure (esp. • Retained austenite • Hardenability • Cleanliness (3)
Intrinsic
(may
qualities
certification
for
grain
• Heat 2 (ch.
size and
no
manufacturer)
banding)
by steel tests
processing
by steel
manufacturer)
exist
are
ensured
by
control,
etc.)
process
control
and
for
peening
• Hydrogen-embrittlement • Material source
Reference
be certified
be certified which
of proper
• Shot
(may
treatment 23)
relief
(type
presents
a
(if required)
of furnace, discussion
dew-point of
gear
inspection
and
the
devices
for
gear
inspection.
2.5.2
Performance
Testing
has
been
used
turbopump
power-gear
that
and
supply
accurate, torque tester formed
and
losses;
thus
tester
driven
systems:
the
to procure
of speed.
a fixed two
by a 100-hp
trains
of several electric
such and
One
torque
gear
a gear load
as a design Several
full power
expensive
in which by
extensively
absorb
as a function
Testing
of the
is locked (fig.
types
diagnostic
run.
Other
most
useful
by torsional tester
horsepower
motor.
50
tool
devices
as dynamometers;
16). The
thousand
and
of loading
these
devices test
use
devices
loading
fixtures
windup prime
in the
of the mover
development
are used, are
methods
has been shafts need
can be simulated
including
the into
supply with
of those
sophisticated, that
impose
back-to-back a closed only
loop
friction
a back-to-back
Driving po_er
Static torque is applied to the coupling and maintained by inserting shims at A
Loaded side of teeth are shaded
Figure
16. -
Sketch
of gear arrangement
in a back-to-back
gear tester.
The used
back-to-back in
the
gear
vibration,
fatigue,
example,
lubrication
simulated prior to
by evacuating starting the
circulation Gear and
and
the test.
feed
gear data
from
expense only
to run-in
back-to-back High-speed
been
for initial
from
obtained
gear
case assemblies)
problems
ambient
in profile
and
solutions during
vehicle
flight
of a new
51
data.
increases, system
hot-fire Since and
and
system
For were
pressure of 2 mm Hg to observe lubricant were and
at each
engine
adequacy.
in a gear
to the difficulties
turbopump
has been
modification,
material
pressures
gear enclosure to an absolute motion pictures were used
information testing
of
uniformity,
low
Successful
telemetered
of gathering
production
correction
processing
arising
behavior. have
used
ultimate
limits,
problems
occasions and
back
tolerance
data
difficulty
(also and
foaming
operational on rare
tester
identification
static
higher
flight
for trouble
developed. engine
tests
assembly
the
tests shooting.
are used
to
C'-I tt_
3. DESIGN
CRITERIA
Recommended
and Practices
,
3.1 GEAR
SYSTEM
Th[ _ gear
systenz
sl)acing, The the
gear
capacity,
mal_e
gears,
manifolds,
and
volutes,
requirements
of power,
design speed,
designer
showing
bearifigs.
the
The
must
lag.
lmp.or.tanti.:•decisions
concerned Initial
in order
estimates
evident
and
cycle may incorporation As the such
of
the be
gear
gear
on
lubricant
for
clearance
for quill
assembly.
case
be met
of
proper
selection
overall
turbopump
system,
used
with data
as the
timely
The
attention
accessibility power
should
be 'performed
and
the gear minimum to
influences gear
design to
those
reference. become selection
systems
be directed and
ducts,
stage.
design-configuration
of fasteners,
must train
design
of
distribution
for future
of
size of pumps,
positions
intercomponent
proceed.
firm,
stackups
in the
and
the
at this preliminary
to provide
that
by
cross-feed of information between design adjustments are made with
modified
becomes
to ensure
for
of rotation, design
documented and
can
responsible
direction
gear
calculations
Tolerance
shafts
and
by
toward
details
of special
tooling
ensure
adequate
axial
accessories.
Speed Ratio
the
gear
Perform
accessory
hydraulic recmirements
pump
shall
system weight
considering hardware practices in selecting Design
be
o./ rotation,
turbopump
by a review of previously used or existing elements already shown to be successful.
delivery
The gear system
speeds.
be
effort
may
configuration
required
Design
size
direction
of the
life
be considered
should wasted
detail-design
shortened of design
gear-system
as the
3.1.1
to avoid
and
primarily
The respons.ible project engineer •should ensure designer and other specialists so that •necessary time
speed,
layouts
position,
effect
and .accessories
for
rigidity.
preliminary
mechanical
lay'o_!ts
and
the
mozmting
review
size.-The:
should
satis./)_
requirements
and
turbine,
i ....
shall
should
system
type
design
load
designer
gear
gear
"-.
satisfy to have and
the
turbopump
a speed
efficiency
or the
for speed,
ratios
to obtain
electric and
to
results
53
Air
speed
ratio.
in optimum the
turbine
optimum
improvements.
required
Observe
tolerance
for
determine
consumption reference 37.
the speed
generator).
for speed
that
studies
weight and propellant system speed; consult
gear
ratio
requirements
for the Force/Navy
if required.
specific
and
pump
configuration
For recommended
accessory
Design
(AND)
(e.g.,
the
Standard
The
reduction
number
ratio
of each
of reductions
mesh
should
reconnnended
be kept
for overall
the (1)
following
sequence
Choose
the
change
within
the spacing Determine
(2)
Check
(4)
Enlarge
3.1.2
limits
requirements whether the
minimum (3)
the
gear
number tooth gears
proper
pinion
as necessary
indicates
tile
Planetary
gear
diameters:
diameters
maximum
(sec.
by the
table
ratios:
that
reduction
3.2.2).
methods
to achieve
will
Increase given
(a) achieve ratio
of pumps and turbines. pinion diameter chosen
of teeth
strength
following
2
the
and for
reductions
1
to determine
mininmm
5. Tile
I,to412to9 i 3to12 i
Overall gear-train ratio Number of reductions
Utilize
below
per
the
pinion 3.1.7.
life
mesh
and
accommodate
in section
acceptable
the desired
and
(b)
the
diameter
speed satisfy
required
if required.
reliability.
Speed Capability
The
gear
s:,steln
shall
operate
satisfactorily
at
the
speed
required
in
the
apl;lication. When
possible,
Higher
spur
speeds
gears
require
characteristics,
should
be designed
special
lubricant
for pitchline
attention
to
and
details
capability,
velocity
measurable of
and
tooth
design
less than
20 000
inherent
gear
in
order
ft/min. quality
to
maintain
be
given
reliability. When
PLV
hibricant
in
a gear
delivery. •
Direct
the
velocity •
design
One
or more lubricant
(speed
exceeds
10 000
of the
following
stream
and
direction)
tile pitch line of the tooth Use baffles and deflectors scavenge
oil thrown
from
of the
the
14-1)
or that
than
25 000
velocities
in reference
to
of the
stream
mesh.
Ensure
is sufficient
that
the
to penetrate
to
the
teeth
and
to
teeth.
face overlap of at least 2 in preference Minimize the sliding velocity between sec.
greater
sliding
side
must
be applied:
as it passes the jet (refs. 20 and 21). to ensure delivery of lubricant to
•
Calculate
lubricant
attention
should
disengaging
In designs
less.
PLV
special
practices
•
or
with
to the
ft/min,
use
double
to spur gears. gear tooth surfaces, by
the
10 (p. 55).
54
ft/min,
method
shown
helical preferably
in reference
gears
with
a
to 60 ft/sec 2 (ch.
14,
Sliding
velocity •
can be reduced
Use
the
smallest
bending
(sec.
Minimize
•
Use a large
•
Use long addendum
pitchline
of the
following
practices:
pitch
that
result
will
in a gear
with
adequate
root
3.1.7).
velocity.
pressure
angle
(25°).
of driving
pinion
(sec.
3.2.5.3.3).
Gear Type
The gear Involute and
diametral
strength
•
3.1.3
by any
spur
accessory
whenever
type
shall
gears
on
drives.
be suitable coplanar
Utilize
for
the application.
parallel
shafts
speed-reducing
are recommended gear
trains
for most
rather
than
main-power-train
speed-increasing
designs
possible.
Involute
helical
or bevel
gears
are
suitable
choices
for
accessory
drives
when
the
loads
are
light. For applications that recommended because balanced gears
axial-load
should
3.1.4
exceed the capacity of spur they have higher load-carrying
component,
be coordinated
and
with
smooth
potential
gears, capacity,
operation.
The
double higher
decision
helical speed
to use
gears are capability,
double
helical
suppliers.
Gear Mounting
The
gear
mounting
method
shall
provide
accurate
location
and
alignment
of the
gear. Utilize and
straddle
gear spans
mounting on deflection
casing
deflections,
shown
in figure
that
the
clearance.
in preference
and
bearing A highly
calculations
thermal
3. Place mounting loaded
to overhung that
effects.
an overhung surface gear should
mounting.
account
for shaft
As a general gear as close
can
be
rule, to the
machined
be made
55
Base
integral
follow nearest
properly with
the
bending, the
bearing minimum
bearing by
its shaft
selection
deflections, proportions
as possible.
providing (fig.
of bearing
4).
adequate
Ensure tool
3.1.5
Gear Attachment
Relative
of" the
motion
gear
and
shaft
shall
cause
tzOt
excessive
deflections
or
fretting. Make on
the
gear
the gear
the
integral
shaft,
raceways
raceway
with
if feasible,
are
the
pilots
as those
When
straddling
the
spline
Provide
shall
sufficient
not
become
backlash
Center
•
Gear
distance
• • •
Bearing eccentricities, Gear eccentricity Gear tooth thickness
•
Gear
tooth
design
tooth
may
be
the
changes
bending
spacing
provided
gear
must
races.
The
heat-treatment
teeth.
See
reference
removable
from
be
to locate
the
under
gear
38
of
for recommended shaft,
Transfer
web.
races
requirements
the
gear radially.
the
inner
utilize driving
Figure
two torque
5 presents
the
gear
Load Capacity
steady-state
Preliminary
from
capacity
caused
gear
contact
In selecting
the
by thermal
reduce
increasing
on the
minimum
contraction
minimum
center
is used,
nondriving
side of the
backlash,
of the gear
theoretical
the
than
loads
of the
the
pinion
long addendum
from gears
distance
or
it is recommended
shall be adequate
designs
tooth
consider
the
case
gear
center
distances
tolerance
rather
3.1.7
Gear load
film.
which
by
tooth
arising
to prevent
deflections
addendum
balance
12).
the
roller-bearing
tolerance
strength
Calculate
for gear
Incorporate
negative.
by
•
a long-pinion
thinning
separate
centered
teeth and to allow for a lubricating effects of the following factors:
Backlash
possible.
Backlash
Backlash
When
when
the gear web
by a loose-fitting involute recommended configuration.
3.1.6
shaft
to eliminate
same
configurations.
tight-fitting
the
tooth.
torque
and
pitch
be roughed
56
reducing backlash
Otherwise,
will be lost (ref.
to transmit
may
by that
part
be of
thickness. obtained
the
by
improved
2, ch. 5).
the design
loads.
radius
as outlined
out
tooth
by utilizing
in reference recommended
2 (ch. values
of unit
load
design
for
satisfies
3.1.7.1
bending
the
TOOTH
The
gear
criteria
ROOT tooth
required
service
Use
the
load
and
layouts
face
stress 3.1.7.1
root
for root
bending
XII.
-
3.1.7.3
possess
compressive set forth
adequate
the applied
load
for
stress.
limits
shown
Preliminary
bending
in table
Design
strength
For
reverse
loading
to 0.7
applying
modifying the
calculating (1)
loaded
values
factors adequacy
the bending
Y for
highest
point
design
calculations
XII for preliminary
Limits
for Face
Load
and
Unit
Load
Face load, ppi
Unit load,
AGMA 1
7 000 2 500 1 500
42 000 25 000 12 400
AGMA 1 or 2 AGMA 1 or 2
1 000 500
12 000 6 000
3a or better AGMA 2
to that
used in aerospace
stress
in both
shown
gearing
of the
diiections
in table
to account
psi
but
has not
been
adopted
as
XII.
of rotation), The
for dynamic preliminary
reduce
preliminary
loading design
(ref.
selected
design
the must
allowable
load
be refined
by
8). on the
basis
of unit
load
by
as follows:
out a large-scale (10× leads to the selection
finding
the
by AGMA.
(gear
of the
strength
Lay that
is equivalent
designation
capacity
Check
grade
to achieve
steel gears
train
material
gear
strength.
Main-power train Accessory drive Nonlubricated (propellant-cooled) Noncryogenic Cryogenic
an official
the
loads.
Gear service
aThis
that
below.
Material grade for carburized
Main-power
Verify
STRENGTH
shall
unit
K values
through
BENDING
life under
and
Table
and
turbopump of single
to 20×) of the gears
tooth
tooth profile to select the tooth geometry factor J. A detailed
is given
contact
(fig.
57
in reference A-l,
ref. 8).
8; base
Y on
form factor Y procedure for the
load
at the
(2)
Use the form and geometry factors found in (1) above to calculate bending
stress:
concentration
then and
distribution.
Table
apply
the
allowable
stress
Xlll
values
gives
formulas modification for
conditions. The factor Kv allows stiffness of rotating elements, load,
Table
XIII. -
given for
dynamic
reference
load,
factor
errors,
load factor
overshoot
presents
characteristics
values
of the
Table
XIV.
-
0.5
to 0.83
0.77
0.5 0.9 0.77 0.83
to to to to
0.77 0.91 0.83 0.91
0.77 1.1 1.3 1.0
for overload
driving
and
Overload Turbine
factor
driven
Ko that
factor
type
axial-flow
centrifugal
1.25
1.50
of stressing,
tooth
utilizing
as given
bending a plot
in figure
strength
of allowable
6.
58
for the operational
and
pumps
pumps
Velocity-compounded, 1 or 2 stages
by
and
Heavy-liquid
1.25
whether
inertia
Ko
1.00
quality
operating
i
account
Many stages
Determine gear
i
Factor Ko Related to Pump Type and Pumped Fluid
Many-stage gas and light-liquid
(3)
stress
elements.
Overload
Turbine
and
Recommended value
condition
Steady state Transient Shutdown
XIV
speed,
root stress
Kv
,
Table
size,
the
for
Dynamic Load Factor K,, for Various Operating Conditions
Range
Start Turbine
tooth
8
Kv for various
for tooth-geometry and tooth stiffness.
Dynamic
Operating
in
is adequate root
tensile
for stress
the
intended
vs number
life
and
of cycles
Modify the designasrequired to meet allowableroot bending stressvalues. Determine gear reliability by consulting figure 7, which gives the probability of tooth breakageduring 1 million cycles as a function of root bending stressfor four gradesof gear material quality. Considerproviding 20-percent excess load capacity to allow for future uprating of the turbopump drive system. Redesignthe gear mountings or gearsupport if the load distribution factor Km exceeds1.5. Specify shot peening of root fillets (sec. 3.4.5) as a means of improving tooth bending fatigue life if high reliability is required of highly loaded gears,or if fatigue life is lessthan that required. 3.1.7.2 The For the
TOOTH
FACE
gear shall
preliminary tooth
K are listed
not
design
pitting
index
in table
COMPRESSIVE be subject
to surface
purposes, K given
STRENGTH pitting
estimate
the
in equations
failure
due
compressive
(2a)
and
to compressive
strength
(2b).
of gear
Recommended
stress. teeth
limiting
XV.
Table
XV. - Preliminary
Design
Values
for Pitting
Index
K i
K value limits
Gear type Main power
Lubricant/Coolant Oil or fuel-additive b Propellant
Accessory
Oil or fuel-additive b Propellant
aThis
material
grade
is equivalent
adopted as an official designation bRP-I plus 2% Oronite 262.
to that
AGMA material grade 1 and 2
Material grade 3a or better
1000 200
2500 500
600 200
1000 500
used in aerospace
by AGMA.
59
gearing
but
has not
been
by
using
values
of
For preliminary turbopump gears For
detail
design,
compressive For design point value.
values
use
the
methods
compressive stress, use Sc K '/2 for gears with 20 ° PA.
of reference
stress at the pitchline and evaluation, use the pitchline
is more
Redesign
design estimates of with 25 ° PA; use 7100
the given
than
10 percent
gear
if the
in figure
greater
8 or if the
51)
or of reference
the stress
gear
surface
probability
at the
pitchline,
compressive
of failure
(fig.
When
compressive
reference
11
allowable
(table
compressive
5),
or
use
stress the
K '/2 for
steel
11 to calculate
is not
larger
of
known the
(as
design
increasing
for
following
use
exceeds
9) exceeds
can be reduced by widening the face, the addendum proportions (sec. 3.2.5).
allowable
then
stress
Compressive stresses diameter, or modifying the
6500
at the pinion's lowest point of single tooth contact. value; however, if the contact stress at the lowest
than
calculated
10 (p.
=
a new
values
as
the maximum
the
allowable
requirements. the
gear
material), an
estimate
pitch
consult of
the
stress:
s,u 1.8 or
Sty Sac
_I
1.5
where
Sac = allowable Stu = ultimate St y - yield
Initiate Deep
fatigue peening
compressive tensile
tensile
testing of gear
stress,
strength
strength
for turbopump gears, because increase in scoring tendency.
for lowest
for lowest
to establish contact
psi
values
surfaces limited
case hardness
case hardness
value,
value,
psi
psi
for Sac. to improve testing
60
compressive has
shown
strength that
this
is not practice
recommended can
cause
an
Recommended
case depths
Table
XVI.
-
to ensureadequate
Recommended Strength
compressive
Case
(20-Percent
strength
are shown
Depth
to Ensure
Adequate
Stock
Removal
Allowance)
in table
XVI.
Compressive
=
Pitch
Finished
Maximum
Case prior to finishing, in.
case depth, in.
grinding stock a
(one side), in.
20
0.012 to 0.020
0.015 to 0.024
0.003 to 0.005
15
0.015 to 0.025
0.018 to 0.030
0.003 to 0.005
12 to9
0.025 to 0.035
0.030 to 0.042
0.005 to 0.007
8
0.025 to 0.040
0.040 to 0.048
0.005 to 0.008
0.030 to 0.050
0.036 to 0.059
0.005 to 0.009 J
ause lowest possible values.
The the
effective depth
calculated
by
Effective Rc
case
to the
depth
lower
carburized
or nitrided
of maximum
methods
case depth
points
for
point
devised should
than
by
subsurface Buckingham
be considered
the
outer
turbopump
shear (ref.
the
depth
surface
power
stress.
39, p. 529) at which
case
hardness,
gears
Subsurface
should
shear
or Dudley
the hardness whichever
be twice
stress
(ref.
can be
10, p. 48).
is 50 Rc condition
or
is 10
is
more
demanding.
3.1.7.3
CHIPPING Tooth
Limit
case
tips shall depth
addendum, The
with
XVII;
chip
tip to twice
width
blended X refers
applied before carburization Y should be more generous corner tooth
buildup root
because
of excessive the
case
brittleness
depth
on the
or stress flank
(fig.
concentrations. 17) or to one-half
the
is greater.
tooth-tip
smoothly table
not
at the
whichever
minimum
Provide
RESISTANCE
is precluded.
should
tip,
end,
to end
and
be 0.25/P and
edge
and should for nitrided Avoid
edge
any
(ref. radii
radii,
have gears
2, ch. 5). (fig.
and
61
Y refers
gear
tooth
to tip radii.
surface roughness of 63/aim and should be applied before
discontinuities
areas.
18) on the
in radii
application,
in accordance
X radii
should
be
AA max.; X and nitriding so that particularly
in
I
I
0.Sa
-maximum
case
a_ addendum
i
Case
depth
at tip
Hardness
_i_
locations
tooth side for case depth
Core test
thickness
test
on
hardness location
Lower limit, working depth
Figure
17.
-
Sketch
showing
hardness
X
locations
for
radii
(tooth
ends
and
Y radii
Figure
18.
-
Sketch and
care
depth
and
tests.
illustrating end
radii.
62
gear-tooth
edges)
(tooth
tips)
tip,
edge,
Table
XVII.
- Recommended
Tip, End,
and Edge Radii
for Gear Teeth
Radius, in.
Hardening method
Y
Main-power gears
Accessory drive gears
0.015 to 0.025
0.010 to 0.020
20
40
10 to 12
0.010 to 0.020
0.005 to 0.010
20
40
16 to 20
0.005 to 0.010
0.003 to 0.008
20
40
6to 10
Max. possible 0.050
Max. possible 0.050
20
4O
12 to 20
Max. possible 0.030
Max. possible _< 0.030
20
4O
5to8
Nitriding
Lubrication
Deterioration life.
Lubricate
and
Recommended For
bearing
3.1.8.1
X
Pitch range
Carburizing
3.1.8
The
of gear
cool
the
lubrication
gear
range
and Cooling
tooth
gear
procedures
HEAT
that
surfaces
tooth
and practices,
by friction
surfaces
guidelines consult
with are
set
and
solid, forth
reference
wear
liquid, in sections
shall
or
gas
not
reduce
gear
coolants/lubricants.
3.1.8.1
through
3.1.8.4.
38.
REMOVAL
lubrication will not
system result
Provide sufficient lubricant well as from external sources coolant involved.
Surface roughness of radii, /_in. AA
shall
maintain
in degradation flow to balance such as turbine
the
gear
of material
system
within
a temperature
properties.
heat input from gear and bearing inefficiency heat soakback. Select the minimum flowrate
that will maintain an equilibrium temperature To achieve this objective, proceed as follows"
63
within
the
capabilities
of all materials
as of
(1)
Determine from
the
gears,
rate
at which
bearings,
and
heat
is to be removed
external
sources.
Assume
of 0.5 to 0.7 percent of the power transmitted reference 2 (ch. 15) or reference 12 for detailed loss. (2)
Add
any
heat
input
from
external
of specific
requirements)
and
summing
the
a gear efficiency
heat
sources
such
as turbine
allowed
(assume
determine
the
inputs
loss per mesh
in spur gear trains, methods of estimating
the gear case or heat radiation to the gear case. Select the maximum lubricant temperature absence
by
or consult gear power
gas leakage 210 °
maximum
inlet
into
F in
the
temperature
expected. (3)
Calculate above
by
specific Convert
the
lubricant
the
product
heat the
against
the
flowrate of
required
temperature
by
dividing
difference
the
found
heat
rate
found
in (2)
and
the
(assume it to be 0.42 Btu/lbm -° F in the absence value found into basic flowrate units and check following
in (1)
lubricant
of explicit the value
data). found
estimates:
Lubricant
type
Minimum flowrate, gal/min/hp/mesh
Oil
6.67x10
5.0xlO -4
Fuel-additive a
aRP-1
Ensure full
that
run
more
the
duration
at higher
Provide
lubricant over
viscosity circulated
3.1.8.2
if necessary
existing should
an associated
presented scoring
component
SCORING
a scoring
total
is adequate
environmental
because
the
to maintain
to maintain
temperature
fluid
viscosity
more
nearly
the
range.
required Most
flowrate
systems
for
will
flow
is lower. constant
flow
by eliminating
the
higher
not
(e.g.,
failure
of a shaft
seal).
PREVENTION tooth index
in descending risk and
supply
262.
at temperatures at the low end of the range. The quantity of lubricant be sufficient to ensure mission completion despite a single malfunction of
The contacting Maintain
the
temperature
heaters
plus 2% Oronite
system
-4
surfaces within order
as a design
shall not the of
experience
ranges
shown
preference.
limit.
64
PVT
destructive in table should
scoring.
XVIII. be
used
The
scoring
only
indexes
are
as a measure
of
TableXVIII.
- Recommended
Method X=
AGMA flash temperature c (ref. 14) PVT calculated at tooth tips (refs. 1 or 3)
s = surface bRP-1
When means
of Scoring
Index
Use
Recommended
Diester oils Fuel-additive b
1.5 min. 1.3 min.
Flash temperature index, °F
MIL-L-7808 oil Fuel-additive b
300 max. 350 max.
Contact pressure (psi) x sliding velocity (ft/sec) x distance from pitch line to point where contact pressure is calculated (in.)
For all turbopump gears
3.0xl
h/s a
value
0 6 max.
film thickness roughness
+ 2% Oronite
CCalculate At in. AA.
on Three Types
Scoring index
Bodensieck (ref. 13)
ah = lubricant
Limits
using
262.
surface
finish
factor
of 55/(55-s)
scoring risk is considered to reduce scoring: •
Reduce
lubricant
•
Increase
•
Use high lubricant
•
Redesign
•
Raise
gears
too
inlet
lubricant
flow
high,
(sec.
pressures to obtain
or
of 50/(50-s)
any
of the
in reference
following
larger
to 600
Reduce
overload
•
Modify
profile
radii
lubricant;
factors
• •
Increase Increase
•
Use finer
pitch.
•
Redesign
the
•
Lower
the pitchline
•
Lower
the
and
of curvature
roughness,
are recommended
as a
lead
gear system
see
table
Ko by reducing to compensate
to lower
VI.
(sec.
torque
(2 or more).
the
3.1.2).
65
loads.
by
using
EP (extreme
Use
only
extensively
sometimes
for elastic
velocity. velocity
of teeth.
of lubricant
number of gear reductions face width.
sliding
steps
s = surface
psi).
additives; these chemically active compounds storage, and this effect is not predictable. •
14, where
3.1.8.1). (60
properties
change
as shown
temperature.
scoring-preventing
additives
instead
peaks. deflections.
become
pressure) tested
corrosive
EP
during
•
Refine
•
AA. Increase
• •
Improve alignment if required. Select lubricant with higher viscosity.
• •
Redesign gears to have lower contact Use contact ratios larger than 1.4
3.1.8.3
the
surface
tooth
LUBRICANT
The
surface
but
do not
hardness
(60
reduce
the
minimum
roughness
below
6/ain.
Rc minimum).
stress.
PROPERTIES
lubricant
stability,
texture
shall
and
possess
acceptable
adequate viscosity
load-carrying over
the
capacity,
range
acceptable
of environmental
chemical
temperatures
of the application. Determine shown
lubricant in table
of lubricants. under
gear
Load
operating
lubricant, oxidizer
in with
case.
load-carrying
VI. Ryder values
Although lubricant avoiding
Alternatively,
Avoid
lubricants
with mixture
temperatures
down
use
of
dithiophosphate 3
percent
below
in most
high
gear
cases
guidelines,
to compare design
oxidizer
use the values
the relative
must
capabilities
be established
cannot
be allowed
by test
to mix with
its compatibility with turbine gas, fuel, or sludging that may occur if leakage enters the filter
volume.
viscosity
at
the
synthetic-base
involved.
elements
and
remove
accumulated
Avoid
lowest
operating
lubricant
is
MIL-L-6086
temperatures.
A
recommended
petroleum-base
when
lubricant
for
0 ° F. mixture
The
compound, by
a new
consider potential
MIL-L-7808
to -30 ° F are
RP-1.
or, as rough
be used
replaceable
excessively
a fuel-additive
using
testing
schedule.
or
at temperatures
by should
with
incorporate
service
fuel-additive
engines
achievable
conditions.
on a regular
The
capacity test results
selecting the a view toward
sludge
service
gear
as the
gear-system
recommended which
additive
should
Exercise
be mixed
caution
to
lubricant is
with
prevent
is recommended
Oronite the
fuel
moisture
262,
a
for
zinc
all
dialkyl
at a concentration
of 2 to
contamination
of
this
compound. Individual 6-month
production batches of intervals for retention
properties design
of this
is not
Select than
ambient
have
been
shown
synthetic-base load-carrying to be unstable.
oil should be retested capacity, because the Use
of this lubricant
at EP
for a new
recommended.
lubricants
fuel-additive (less
lubricant
MIL-L-25336 of specified
with
mixture 2 psia).
are
demonstrated
foaming
recommended
for resistance
MIL-L-6086
oil foams
extensively
pressure.
66
resistance.
MIL-L-7808
to foaming and
should
at low
be avoided
oils
and
ambient for service
the
pressure at low
With the exception of RP-1, propellants in general should not be used as gear coolants. Consider propellant cooling for applications with short life requirements, loads below 500 ppi, and speedsbelow 10 000 ft/min PLV. Testing should precede inclusion of propellant lubrication in final design. Use solid-film lubricants where loads, speeds,and intended life permit. For information on solid-film lubricants, consult reference40 and section2.1.8.3
3.1.8.4
LUBRICANT
The
lubricant
shall
weigh
Splashed-oil
delivery as little
and
less than
DELIVERY
Once-through
with
systems;base
Use
positive-displacement
the
temperature
range
of
lubricate
adequately
these
will
should
be
10 000 be
and reliably
and
for flow
lubrication will maintain
a constant-pressure
of withstanding
only
systems
of
pressures
short-duration
10-percent
excess
and
duty-cycle
systems
that
a more
pressurized
the
for gear
one-duty-cycle,
Provide
on maximum
pumps
used
ft/min.
used
lubricant.
for feeding
because
is capable
should
as the
reserve
pumps than
less than
flow
additive
calculated
range,
system
and
systems
velocity
drain)
temperature
lubrication
lubrication
pitchline
oil or fuel
such
shall cool
as possible.
(overboard
applications
wide
system
grease-packed
1O0 hp, with
SYSTEM
for
duration. must
constant
operate flowrate
system.
resulting
capacity
Ensure
over
a
over
a
that
from
low-temperature
total
weight
the
operation. Recirculating lubricant, tanks,
lubricant feed
lubricant,
lubricant
3.1.8.4.1
feed
or 60 percent Lubricant
gear tooth
surfaces.
lubricant radially
lubricant
penetrate
to the
toward pressure
pitchline
heat
when
exchanger
and system
is lower
controls
for
should
have
of the volume
the
flowing
than
the
total
a once-through a capacity
of
tanks,
weight
system. of
100
of The
percent
in 1 minute.
Nozzles shall
nozzles
inward
recommended
or pressurant, recirculating
nozzles
delivery
supply
and
(minimum)
Spray
delivery
directed
the
are
pumps,
pump
for
Lubricant
Place
systems
scavenger
reservoir
(preferred),
The
and
flow
on the
the
and
an adequate
disengaging
center
should
of gear
deliver
quantity
side
of
the
of lubricant
to the
mesh,
with
the
a jet
velocity
stream
of each gear. be
sufficient
pinion.
67
Methods
to
result
in
of calculating
the
required
that
will
velocity
are presentedin reference 21; a supply pressureof 400 to 600 psi is recommendedfor gears with PLV of 20 000 ft/min or greater. The nozzle spray should cover the entire face of both pinion and gear;a rule of thumb is to provide one nozzle for every 1/2 in. of gearface width. The minimum nozzle outlet orifice should be 0.015 in. in diameter to reduce clogging tendency. 3.1.8.4.2
Foaming
Foaming Excessive
of lubricant
foaming
should psia
minimum
3.1.9
by
which
selecting
with
gaseous
additives
to the
gear
alignment Make
Isolate
cooling
sometimes
low-foaming
nitrogen
or
occurs
at gear
lubricants, gaseous
by
case pressures
pressurizing
helium,
by
using
provide
rigid
below
the
gear
baffles,
or
2 psia, case to 5
by
adding
lubricant.
deflection deflections. of similar
envelope and
turbopump with
the gear
ensure
system for,gears
overall
compatible
gear case
adequate analyses When gear
forces,
calculating
gear
case)
to
determine
whether
pump
external
duct
structural
considering
all
utilize
Internal
and
thermal
strength
internal
the
forces
separating
loads
results
and
and
stress
loads
from
deflection
possible,
the
gear
distortion
by thermal
ducts
forces,
and
axial
in reference
should
analyses case
with
and
where
rigidity,
good
turbine
spacing
is
external
forces
loads
12).
be eliminated
if the
should
or mechanical
be
ducts made
when
as symmetrical
loads.
68
by the as
stress
and
temperature-induced actual
operation
loads
arising
from
helical
Gear-case
possible,
are supported
detailed
during
bearing
from
2 (ch.
and
taken
include
practical.
perform
of measurements
to be considered
are given
loads
be considered and kept as low as feasible (5 to 40 psig). and radial loads must be added when they are supported
External
mounting
distance.
gear-case
reactions
shall
bearings.
center from
(gear
layouts
possible,
cases.
tangential
the
not degrade
Gear Case
The
must axial
shall
of lubricant,
be prevented
antifoaming
To
of Lubricants
gears.
Methods
internal
pressure
Pump and turbine on the gear-case as they gear-case possible
must
of also
impeller structure.
be included
structure. to
gear
reduce
Whenever possible
in
Provide
clearance
tcmperatu,
es and
Fasteners are
and
required
for
bolts
should
installation gear-case Crack
of gear-case
with
sufficient halves
duct
brittle
and
fit.
a mininmnl
the
box,
Avoid
lacquer
application
of the
fasteners
full
deflections
bores
number
due
to
of special
tools
assembly,
and
turbopump
inside
the
gear
applied
load
required
components bearing
gear
(stress-coat)
will indicate
Locate
so that of
system.
of gear-case
press
clamping tinder
joint. Use O-rings whenever possible. the
due to failure case.
force
loads.
or other
effects
of
of seals)
GEAR
will
to gear
reveal
design
case.
the
case
outside
magnitude
and
modification.
by use
of locating
pins
by line
boring
assembled
the
or dowels
with
gear
case
with
Clamp recessed
screws
the gear-case seals (not
malfunctions
so that
some
of
or bolts
gaskets)
of
prevent
relative
movement
together
with
a metal-to-metal
to prevent
associated
redundancy
to
components
leakage
components
or margin
from
(e.g.,
of safety
parting
planes
overpressurization
is designed
into
the gear
DETAIL
Pressure Angle
The pressure A 25 ° pressure gears,
Consider
pins installed.
Provide
3.2.1
volutes.
accessible,
engine
during
relocation
gear-case
3.2
and
disasselnbly
using
strains
or slight
Anticipate
in the
pattern
accurate locating
and
strength
direction
line-to-line
manifolds,
be made
assembly
surfaces.
Obtain
ducts,
pressures.
for
turbopump Test
for
angle angle
particularly
3.2.2
The
of the gear shall is recommended
if long-addendum
not
detract
from
in preference ,pinion
teeth
on a gear shall
satisfy
the
tooth
to lower
are used
load capacity.
values
(see sec.
for
turbopump
power
3.2.5.3).
Number of Teeth
mtmber
opera tioHal Choose the constraints:
of teeth
or mamtfacturing
number
of teeth
the
gear speed
ratio,
yet
not
result
in
difficulties. required
to
achieve
69
the
specified
ratio
within
the
following
11) Select gear pitch that provides adequatestrength: if bending (2)
strength
by using
Avoid undercutting that the number
coarser
pitch
and
therefore
pinion teeth by adjusting of teeth does not fall below
necessary,
fewer
increase
tooth
teeth.
pinion pitch the lninimum
and pitch diameter so given in the following
chart:
Power gears, minimum teeth
Accessory gears, minimum teeth
20
26
22
22.5
23
19
25
20
16
Pressure angle, deg
(3)
Establish with
(4)
the
Ensure teeth
(5)
number
the natural
hunting-tooth in meshing
Limit
the
Contact
The
The at
ratio, greater
3.2.4
meshing
maximum
there
number
of
costs
are likely
frequency
or any wear
life
are no common teeth
to
100;
does
not
coincide
of its elements. by
choosing
numbers
of
factors. otherwise,
manufacturing
and
to be excessive.
tooth
loads
to
successive
teeth
shall
not
produce
excessive
loads.
contact gears
and
so that
of
a value
loaded
action
tooth
gear system
Ratio
transJer
dynamic
gears
so that
of the
maximum
quality-control
3.2.3
of teeth
frequencies
calculated than
because
1.2.
of the
with
the
formula
Use
1.5
when
inherently
given
in reference
possible.
low
contact
not
result
Avoid
10 (p. 55),
stub-tooth
should
designs
for
be kept highly
ratio.
Face Width
The
width
o.[ the gear .[ace
shall
in uneven
load distribution
across
the
./ace. Keep helical
the
ratio
gears,
of face the
total
width width
to pitch for both
diameter helicals
(F/D) should
7O
less than not
exceed
1"1 for spur twice
the
gears. pitch
On
double
diameter.
The following effective valuesfor F/D arerecommendedfor turboptunp pinions: EffectiveF/D values Preferred maximum Limit
Geartype
3.2.5
Tooth
Tooth the
gear
and
in reference
(sec.
3.2.5.5)
3.2.5.1 The
full-depth
Accessory-drive special
design
Helical
0.60
0.9
Doublehelical
1.1
2.0
proportion 26
whole
0.7
shall
for
as required
prevent Use
tooth
WHOLE
0.5
Proportions
proportions
Use
Spur
fine
ensure
maximum
system pitch
listed
(Pd
to obtain
strength
and smooth
in reference
>_--20)
involute
the maximum
25 gears.
load
tooth
for
coarse
Include
action. pitch
profile
(Pd
_
19.99)
modifications
capacities.
DEPTH depth
shall
use of adequate standard gear goals
tooth designs
exisL
not
sacrifice
fillet
radii.
form should
use the
strength,
proportions follow
following
make
as listed
manufacturing
in reference
the standard
proportions.
whole-depth
values:
Gear type
25 whenever For gear
Whole depth 2.35
Main-power-train gears with adjusted addendum and dedendum
2.40 tO
Pd
Pd
2.25 Moderately gears
difficult,
2.35 tO
loaded accessory Pd
-Pd
2.25 (standard)
Lightly loaded accessory Pd
gears
71
or
possible.
designs
where
Stub
teeth
used
for
(those
in which
accessory
and
the
gears,
sharp transfer of loads. Stub additional tooth tip clearance.
3.2.5.2
TOOTH
Tooth
teeth
working
because can
thickness
backlash
2 (ch.
5, p. 5-20)
be used
by
values
shall
thinning
the
for design
not
reduce
3.2.5.3.2
gear
tooth
procedures
proportions
shall
values
proportions
of addendum
equal-strength with
teeth
of the
increase
the
gear.
For
driven must
be made
A) and
3.2.5.3.3
obtain
shown
not
rather
cause
than
teeth
in internal-gear
the pinion
in selecting
undercutting tooth 3.
in equal
in figure
not be restllt
design
tooth.
tooth
ill
to give
Consult
reference
thickness.
of teeth. undercut.
whole
addendum gears
in pinion
depth
Proper
values
for
spur
and
from
similar sheet
strength.
gears
with
20 ° pressure
and
gear.
Figure
11 also
pinion
and
equally
decrease
for which
figure
angle
to obtain
can be used
for
is used.
of the driving
different
to generate
bending
11 for spur
Y factor)
same
25 (information
those
charts.
Calculation
the
11 is valid,
methods
are given
addendum layouts
in references
and 8
B).
Equal Sliding Velocities
Addendum
figure
) should
strength.
to be used
shall result
(balanced
25 ° PA if the
In general,
To
of stub
Equal Strength
Addendum
(App.
2.00/Pd
ratios
to advantage
tooth
Use the required pinion addendum to avoid helical gears are shown in figure 1 of reference
tests
is less than
contact
Undercutting
Addendum
gears
low
ADDENDA
3.2.5.3.1
Use
depth
the
THICKNESS
Obtain
3.2.5.3
theoretical
power
equal
proportions sliding
2 of reference
shall
velocities
3 (for
result above
in minimum and
20 ° PA) or figure
below
sliding the
pitch
3 of reference
72
velocities. line, 3 (for
choose 25 ° PA).
addenda
shown
in
In summary, which
establish
are listed (1)
No pinion
(2)
Root
(3)
Sliding
(4)
Peak
When
untried
3.2.5.4
the
fillet
velocities
addenda
radii
of addenda
oll the
basis
of the
following
factors,
of importance:
maximized
compressive
ROOT
values
order
undercutting
strength
by equalizing
minimized stress
pinion
by adjusting
and
radii
gear
strength
of curvature
minimized.
proportions
are used,
confirm
design
adequacy
by gear
tests.
FILLET
Gear-tooth-root Root
design
in descending
fillet should
radii shall
be maximized
for fillet radii for 25 ° PA aerospace be calculated as shown in reference
not
result
in excessive
to minimize
root
gears are shown 25 (information
stress
bending
concentrations. stress.
Recommended
in figure 19. Limiting sheet B).
radius
values values
0.37
\
For
gears
with
value ÷ P pitches, use
other
chart
%
O. 34
o" 0.33
.. _o ,0.3o
_o._
<,, _
,,
0.29
k
0.28 17
20
24
30
40
Number
60
80
of Teeth
Figure 19. - Recommended root fillet radii vs number of teeth (25 ° PA spur gears).
73
125
.o
may
A large-scale the
root
The
gear
the
(20×
fillet
3.2.5.5
and
grinding
tool
design
limits.
Involute
Tooth Modify
bending
1000
the ppi
profile
be
used
for
27 to calculate
3.2.5.5.2
Tip Relief
allow
for
of active profile
tooth
for
only
relief
3.2.5.5.3
When
the
be made
to ensure
that
tip.
review
not adversely at face
the
chosen
this
and
affect
loads
estimated
13(a))
radii
to ensure
ppi
deflection
drive
action.
deflection
of tip and
accessory
tooth
of 2000
a tip bending
(fig. required
not
the
interfere
errors,
gears
above.
of 0.00035 exceeds
root.
gears.
and
0.0005
Tip-only Employ
in. per in.,
modification the
methods
of
modification.
that
at start
provide
a tip relief
will
operate
to zero
at the
profile
contact
of rnesh.
at
speeds
25 percent
modification.
ratio
does
not
of 0.0005 exceeding of active
Recalculate drop
in. for the
below
15 000 profile
contact
first
25 percent
ft/min
depth ratio
PLV.
point
of gears
The
if speed after
tip
1.2.
Lead Modification deflection
the
teeth
0.0005
in.
is recommended
end
should
tooth
for Speed Effects
Crown
Gears
shall
assuming
power
in detail
requiring
that
Gear tooth concentration.
lead
gears.
can drop
factor
to ensure
profile gear
should
operating
by
loaded
manufacturing
profile
gears
modification
tips shall
modification
is the
steel
profile
reference
To
loaded of all gears
on lightly
The gear
manufacturer
modification
load
"barrelled"
tooth
mating
for Load
of highly
required
face
consider
the
MODIFICATION
Modification
the involute
Estimate
of the gear with
of cutter
TOOTH-FORM
3.2.5.5.1
layout
will not interfere
cutting
feasibility
may
minimum)
radii
chart
for a properly
supported easing
of gears
in rigid
as shown
or
that
misalignment
may
for
be subjected
highly
crowned
gear
gear
cases,
in figure
13(c)
shall
loaded
not
result
to misalignment. gears.
See
figure
in
excessive
Crowning 13(b)
for
stress
of 0.13002 an example
to of a
tooth.
while
not
to prevent
74
requiring stress
crowning,
concentrations
should
be provided
at the ends
of the
with teeth.
For gearswith F/D values greater than 0.5 or with face widths over 1 in., consider helix correction to compensatefor torsional windup of the geartooth. A preliminary estimate of the required helix correction is 0.0002 in./in, of face width. Lead modification values recommendedherein should be used as preliminary designvalues in the absence of testing experience. For a more detailed calculation of theoretically required modifications, consult references41 or 42. Normally, lead corrections should be limited to 0.0006 in. maximum to avoid contact stress increaseand reduction in load capacity. Test for lead modification required to compensate for misalignment by coating the teeth with flash copperplate, operating the gear mesh briefly under reduced load, and studying the contact pattern created.Repeat this test after applying profile modification to confirm its adequacy. This procedure is especially important for bevel gears;however, to determine proper lead modification for the torsional windup, the gearsmust be run under full load. The effects of torsional windup may be reduced by driving through splinesaxially located at the center of the gear face (e.g., the pinion shown in fig. 4).
3.2.5.6
SURFACE
The
shape
contact The
rate
TOLERANCES of
the
active
involute
or lead
of reversal
is acceptable
should
for
accessory
by examining
not
exceed
,
drive
the traces
l/ -
shall
not
result
in high
local
stress. 0.0002
involute or lead profiles for 8- to 12-pitch must not be concave (fig. 20). A dimension reversal
surface
and
/
any
25-percent
portion
and
loaded lead
power
gears.
Determine
/
I :llllll l (b)
Acceptable
Figure
20.
-
Acceptable
and
75
the
charts.
f/i:
/
///ill (a)
of the
active
power gears. In addition, the overall lead pattern of 0.0003 in. per 25 percent of the active profile
lightly
on involute
in. for
unacceptable
Unacceptable
lead traces.
(concave)
l
rate
of
3.2.5.7
SURFACE
3.2.5.7.1
Contacting
The
surface
resistance
Grinding
score
texture and
surface
should
not
Surfaces
of
fatigue
not Do
not
only
are
than
as the
texture
exceed strive more
in #in.
for
surface
with
Table
Surface
contact
final
the
50
directions
roughness
XIX.
-
values
Recommended
max.
Power gears, PLV < 25 000 ft/min
6
20
Power gears, PLV > 25 000 ft/min
6
16
Accessory
6
40
Noncontacting Roots
drive gears surfaces
not
for
illustrated
in
values values but
for less
adversely
Values
tooth
affect
than
scoring
12.
6/.tin.
AA
for Gear
Peak-to-valley
and
AA,
are because
such
greater
20
AA.
#in.
waviness
shown
to have
Surface
machining
profiles.
roughness
appear
6 #in.
Preferred
contacting
figure
surface
actually
between
Surface roughness, _in. AA
surfaces
shall
method
to manufacture
roughness
min.
Contacting
surfaces
finishing
Recommended
expensive
surfaces
tooth
life.
is recommended
Measure
XIX.
TEXTURE
operation
Grinding
Very
(I) Hobbing
Very critical
(2) Shaping (3) Grinding
critical
(do not grind
after case hardening) Mounting
surfaces
32
Grinding,
turning
Critical
Rims and webs
125
Crush grinding
or turning
Important
Hubs
125
Crush grinding
or turning
Important
Lands and tips
125
Minimal
76
tendency
Importance of surface condition
max.
64 100
surfaces
Roughness
and Fillets:
Before peening After peening
in table
to
A light glass
vapor beads
texture
blast
or peening
requirements
program
that
3.2.5.7.2
compares
stresses,
XIX
presents
shall
3.2.6
Rim and Web
3.2.6.1
RIM AND
residual
webs
minimum
weight
Web
thickness
should
0.20
in.,
the
are
fraction Avoid
of the
root
contain
area
shot
be determined
surface
or
Surface by
a test
textures.
harmful
expensive
stress
concentrations
or
to manufacture.
roughness
values
and
production
finishing
must
not
be permitted
because
this process
will
stresses.
lowest
gears
be less
the
shall
carry
the
required
load and
shall
be of
are between
0.10
cost. than
same
size
lightening-hole
0.10
in. When
as the
face
face
and
proportions
and
web
web
proportions
XX;
dimensions
rims
stock shot
and
in table tooth
bolted
sufficient
tensile
not
surface
tensile
never webs
rim
shown
inaccuracy
Specify
should
different
small-size
performance.
widths
utilize
for lightly
lightening
loaded
power
and
holes
to reduce
gears
are shown
21.
Recommended PLV)
shall
on power
and
Recommended
in figure
blasting
with
with
WEB PROPORTIONS
and
make
of gears
not be excessively
in the
undesirable
weight.
after
surface lubrication
gear surfaces.
carburizing
rims
contacting
borderline
gear
recommended
produce
The
finished
surfaces
yet
for nonactive after
tooth
Surfaces gear
residual
Grinding
the
gear
improving
performances
Noncontacting
methods
for
for
Noncontacting
Table
of the
is recommended
whole and
fretting
stress,
webs, at
for weight peening
depth
or on gears
from
to figure
experience 14 and
(up are
to 25 000
presented
ft/min
as a decimal
h t.
because the
removal
of gear
derived refer
rims that
bolted
joint joint.
as shown and
deflection If
balancing
in figure
webs
are subject
77
of
undesirable gears
gear
is required,
meshing provide
22.
on main-power to web
causes
fatigue
gears failures.
or other
gears
with
high
\\
Avoid
extension
of lightening hole into web fillet radius
0.7dto d
Figure
21.
-Sketches design
illustrating of
lightening
78
recommendations holes.
for
Table
XX.
-
Recommended Number
Item
Rim
and
Web Thicknesses
of Web-Lightening
Main power
Cryogenic
and
Holes
and moderate
Light power gears
power accessory Rim thickness*
1
1
0.7
Web thickness*
1
0.7
0.5
Number
*Thickness
of lightening
in inches
whole
None
holes
= factor
shown
times
tooth
Odd numbers
whole
5, 7, 9, etc.
depth.
depth
Minimm
thickness
rim
= ht ebia_kremg ved
te_;emovedfor
(b) Alternate (a) Typical
Odd numbers 5,7, 9 or even numbers >6
rim
rim
configuration
configuration
Figure 22. - Recommended locations for stock removal for balancing.
79
3.2.6.2
GEAR
RESONANCE
The gear The
shall
frequency
part
of
3.2.2). factors.
of gear tooth system.
Hunting-tooth of lightening
the
and
natural
resonant
precise
frequencies,
Campbell
diagrams
per second
Avoid
designing
expected
and
the
Provide
case.
or other
components
rather gears
of the gears
3.2.7
Tolerances
Use
the
table that
For
VII. the
Finer
designer
critical
to
if the calculated
spur
gears
yet
shall
that
power
tolerances
its torsional
gear range
from
frequency
by accelerometers
a few
to
are discovered.
forces
balancing
is in the attached
amplitudes
imbalance
to include
to establish
frequency. natural
if destructive
plan
sensors
are detrimental
provisions
on other
gears.
for
tolerances
must
or shaft
for low
piezoelectric
should
mesh
be detected
be initiated
gears
for reduction
specified
coarsest
application.
on the
and reliability,
may
in reference
is recommended
for each
investigated
that
modal
frequencies.
operating
such
If possible,
in preference
are recommended
capacity
should
components. than
Frequencies
The
are adequate
and
be constructed
maximum
system
testing
(sec.
common
or test.
methods salt)
gear meshing
Resonances
action
Dampers
Tolerances
shaft
sand-pattern
contain
as outlined
however,
of any
vibrations
not
calculation
be calculated
(popcorn
should
modes. of the
range.
Corrective
for balancing
helical
and
speed
to bearings
Use
gear
and
salt
diagrams)
resonant
can
by
should
range.
frequency
reinforcing
gears
accurate;
for determining
to 150 percent
operating
gear
tables
table
to avoid
design
gears
Shake
to a resonant
of mating
gear
reasonably
(interference
frequencies
cycles
new
in the gear operating
correspond
is desirable
are
fine-grained are required
not
of rimmed
frequencies
resonances
in webs
of any
determination.
(accelerometers)
action
frequencies
but
should
holes
frequency
calculated
or lateral
meshings
number
for more
the
torsional
the
23. These
forcing
have
The
Determine shapes
not
will
gears,
will require
coordinate
and
when
vibrational
of vibrational
response
shaft not
be
precise
exceed
the
use AGMA development
8O
enough
to
capacity
quality on
by actual
levels
and
are
anticipated.
rims (ref.
achieve
the manufacturer's
satisfy
evaluate
problems in gear
21).
good
life
requirements
9 to 13 or the values
the
part
gear
test.
load
.capabilities.
of the
gear
of given
manufacturer
the in
3.3
MATERIALS
3.3.1
Gears
The properties Material
recommendations
are
are
in
considerations properties tests
of the gear material
presented
by invoking
as necessary
Materials
used
uniformity
in
over
Recommended protection
(1)
Cover
the
be provided gear
Maintain
Plate
require ground
surfaces
is not
0.0003
during
new
and
Ensure
specifications
be
work
specific
material
consistent
material
and
purchased
in
be performed
the
not
quality
mill
cleanliness,
on
lots
control
to
ensure
a main-power
hardenability,
gear
and
carbon
lubricated
with
with
for
per
MIL-P-27401
or
per
QQ-C-320
plate
is preferred
an accurate,
hard
surface.
to the
required
recommended.
to 0.0005
For
in. on
gears
for
Tbe size.
the
corrosion
or areas
plating
enclosed
gears
such
as
per
electroless
nickel
per
as locating should
plating
in cases,
idle
helium
thickness
plating,
throughout
gaseous
such
Chromium
nickel
compounds
fuel-additive.
atmosphere
Chromium back
preservative
oil and
protective
chromium
therefore,
means:
periods
nitrogen
with
corrosion-resistant;
following
idle
inert-gas
gaseous
exposed
lubricants
are
for systems
surfaces
surfaces Dry-film
XXI,
3.3.1.2.
should
will meet
by one of the
continuous
oversize, are
and
or machining
material
surfaces
MIL-C-26074. which
table
or establish
materials
periods with MIL-P-27407. (3)
3.3.1.1
requirements.
for the gear.
MIL-C-16173
(2)
in
gears
forging
power-gear must
design
run of gears.
no
that
requirements
sections
standards,
a production
it is established
content
summarized
turbopump
that
satisfy
consistency.
critical
It is recommended until
existing
to achieve
shall
surfaces, be 0.002
of active
gear
recommended or 0.0009
in.
tooth
thicknesses
to 0.0011
in. on
to the atmosphere.
(sec.
2.1.8.3
and
ref.
with
propellants
40)
can
offer
a
low-cost
means
of corrosion
protection. Lubrication is contemplated, should
of power
gears
consult
be an integral
part
section
2.3.1
of any gear
alone
for materials design
project
81
is not that
recommended; have
involving
been
used.
if however, Testing
propellant-lubricated
such
use
of materials gears.
Table
XXI.
-
Recommended
Materials
and
Material
Requirements
Item
Material
quality
Intended
use
grade
AGMA 1
AGMA 2
Accessories
(alloy designation)
Medium
power
Main-power
4a Very critical gears
train
AMS 6265
AMS 6265 b
AMS 6265 b
9315 3310
AMS 6260
6260 b
AISI 9310 b
AISI9310 9315
AISI 9310 b
8620 4620
4340 percent
Core Hardness, Case
3a
AISI 9310
8620 4620
oo
Gears
Recommendation
Material
Carbon content, Case
for Turbopump
Rockwell
Per material
specification
0.75 to 1.00
Per material
specification
Per material
specification
0.75 to 0.95
0.8 to 0.95
0.10 to 0.13
0.11
to 0.14
"C" scale 58 minimum
58 to 63
60 to 63
61 to 64
31 to 44 No
32 to 42 Optional
34 to 42 Yes
38 to 42 Yes
No
Rarely
Yes
Yes
No
Optional
Yes
Yes - special requirements
Loose
Adequate case
Grain size (per ASTM E t 12-63)
3 to 5
5 minimum
Carbide network
SrrmU continuous allowabIe
Core Size effect considered Material
purchased
in registered
Cleanliness
requirements
Case depth
control
Retained
austenite,
(a) Determined
mill lots
specified
percent
noted,
bsp_cial
not
currently
hardenability
an and
Networks required noncontinuous
Adequate to ensure unitbrm case
thick,
6 minimum to be
No significant allowable
Adequate to ensure uniform case
AGMA-designated procurement
grade.
requirements.
thick,
7 minimum networks
No significant allowable
maximum
by visual examination
under magnification (b) Determined by X-ray diffraction
aAs
networks
to ensure uniform
15
10
5
3
25
15
15
13
networks
3.3.1.1
IViATERIALGRADES
The quality Gear
materials
The general recognized
of gear nzaterials must
be graded
requirements by AGMA
shall
meet
to achieve
the specified the
design
performance
requirements.
required
for turbopump
service.
for the grades are listed in table XXI. Grades 1 and 2 are presently (ref. 3) for aircraft quality gears. A new designation, grade 3, is
recommended for most turbopump mainpower gears; for even more critical applications, a potential grade 4 is listed. Uprating and increasing performance requirements require an upgrading of the gear quality, but cost and schedule considerations require that the designer specify the lowest grade that will meet the requirements of the design. AMS 6265, a vacuum-melted aerospace gearing. Allowable
AISI 9310 carburizing steel, is recommended for most bending and compressive stress levels are given in section 2.1.7.
H-bands should be specified for critical gears to control the material hardenability. For the same reason, the carbon content should be specified to tighter limits than standard (table XXI). Reference 43 (pp. 189-216) presents the important aspects of hardenability of steels.
3.3.1.2
METALLURGICAL
The metallurgical design. Specify the requirements for carburized
PROPERTIES properties
of the
hardness requirements on on the gear forging drawing. steels in the various grades Table
XXII.
-
Recommended
materials
shall
meet
the
requirements
of
the
the gear drawings; specify the hardenability The recommended case and core hardness ranges are shown in table XXII; the higher values of case Hardness
Values
for Carburized
Gears
Hardness AGMA grade 1
AGMA grade 2
Grade 3 a
Grade 4 a
89.2 min.
89.2 to 91.5
90.2 to 91.5
90.5 to 91.7
58 min.
58 to 63
60 to 63
61 to 64
D = 0 to 6 in.
31 to 44
32 to 42
36 to 42
38 to 42
D=I
31 to 44
32 to 42
34 to 42
36 to 42
Use
Case (Rockwell
15N superficial
hardness) Case b (Rockwell Core (Rockwell
C) C)
to 12in.
aAs noted, not currently an AGMA-designated bMeasure with 15N scale on profile of gears
grade. to be placed
in service.
83
hardnessshown in tile table are more desirablethan valuesat the low end of the acceptable band. It is recommended that, when contact stress is critical, the acceptable band of hardnessbe narrowed by raising the lower limit to the value of the next higher grade. Grade 3 is recommended of Grade
for most
3 gears
is shown
turbopump in table
Table
power
gears;
detailed
recommendations
for hardness
XXIII.
XXIII.
-
Recommended Material Grade
Hardness 3 a Gears
for
(Carburized)
Case Equivalent D, in.
Core R c
Rc
15N
0 to 4
36 to 42
60 min.
90 min.
4 to 8
34 to 42
60 min.
90 min.
8 to 12
32 to 42
60 min.
90 min.
aAs noted,
No and
continuous
carbide
discontinuous
metallographic Carbide
appear sizes
amount
undesirable
as the
15 percent
retained
3.3.2
be
gear
500
may
(table
to
times
in. are
austenite,
material
austenite
be allowed,
beneficial
to 0.0003
retained
an AGMA-designated
although the
total
become
carbide
performance
too
The
case
absence brittle.
networks of
is recommended
acceptable.
but
grade.
of
that
turbopump
are
fine
gears.
A
for evaluation
of-carbides.
structure
not
retained
Turbopump
must austenite
gears
have
an
could
should
have
be 5 to
XXI).
Gear Case
Gear-case lubricants Cast
to
may
magnified
up
of
currently
networks
specimen
particle
excessive
not
materials used
aluminum
applications. corrosive
materials.
be
chemically
and structurally
alloys Cast
shall
suitable
A356-T61,
The
specific
steels alloy
nature
must
with
for supporting
A357-T61,
corrosion-resistant
the highly reactive chemical contact with oxidizers.
compatible
and
should
Tens-50
be used
be compatible
of magnesium
84
the
alloys,
the
are with
and
loads.
when these
coolants
recommended the
gear
for
case may
the
propellant.
alloys
should
most
contact
Because not
be used
of in
Table
XXIV
Reconunended
Processes
and
Process
Controls
for
Fabricating
Turbopump
Gears
Recorumendation
Process
or Control
Accessories
F.rging
Use
of
Medium
forging
optional
Open
power
or closed
MAin-power
die
forging
required
Testing
and
fl)rging
source
train
qualification
Very
of
die
and
required
Forgings
critical
with
gears
integral
qualification
of die
teeth and
recommended
forging
source
re-
quired
('uuer
control
Finishing
No
method
for
profile
Only
Grind,
surfaces
hone,
lap
or
Grind
shave
Rot)t
Ireatment
after
carburization
on
burn
Detection
acceptability
Grinding
allowed
Light
method
Stock
remowll
burns
accepted
Small
percent
of run
radii
c,.m::rol
critical
Grind
required
cutters
Grind
required
are
registered
(new
methods
may
be
re-
not
but
recommend-
No
grinding
permitted
No
grinding
pernritted
allowed
None
accepted
None
Nital
etch
Mild
accepted
nital
None
etch
accepted
Mild
nital
etch
a
percent
of
run
in-
100%
of
run
inspected
100%
of
run
inspected
Small
percent
of
run
in-
100%
of
run
inspected
100%
of
run
inspected
spected
percent
of
run
Large
inspected
Shot
on
Yes
quired)
Large
inspected
Fillet
required
Grinding
Visual
control
Yes
gears
gears
ed,
(.;rinding
critical
spected
peening Roots
Special
Rims
No
Special
Webs
No
No
Heat-treatment
cases
only
IX
Pit,
brick-lined,
or
Processing
2X
tO 4X
4X
minimum
2X
to 4)(
4X
minimum
2X
to 411
4X
minimum
control
Magnetic
particle
Analysis
of type for
or vacuum
Stainless
or infrared
Prefer
teeel
or vacuum
retort
Vacuum
retort
Infrared
gas
Dew
point
or
car-
Dew
pack
point
gas
infrared
gas
analyzer
inspection
Yes
Yes
Yes
Yes
Optional
Optional
Yes
Yes
carbon
content
melhod
for
carbide
Randonr
sample
examination
determination
Examination
visual
ot" micro-
structure
under
nification; optional
type
at
microstructure
mag-
type
analyzer
only
analyzer
Ib
heat-treat
only
retort
burizing
network
only
Brick-lined
better
Inspection
cases
furnace
Type
sample
intensity
heat-treat
500X of
of
type
2
sample
Examination treat
at 500X
sample
quired,
type
type
of heat-
2 or,
when
level
on
Examination re-
sample
at
type
IO00X
of heat-treat
3
30
I or 2c
sample
Retained
austenite
determin-
Random
ation
check
microstructure amination ray
htspection
of all
gear
dimensions
or
by
Microstructure
examin-
Determination
ex-
ation
diffraction
gears
X-
on
or X-ray large
enlbrittlement
relief
required;
Sampling
Required
bake
sample
is a rod
C]leaHreal dlleat-lreal
sample salnple
is f[Olll Ihe S[llllC nlaterial ao.,t has the Sallle is a sectitm cut fronl :in actual gear.
of inspection
equipment
lllateri.,5
or
on
large
per-
X-ray
Required
of gears
at 325 ° F for 2 hrs.
blleal-treat
e Fraccability
of tile same
of run
of
microstructure
100%
examination
diffraction
of
Determination by
of
nricrostructure
X-ray
level
on
100%
examination
that
accompanies
the cross
gear
section
through
its heat-treatnlenl
cycle.
as tile gear.
Io standards.
85
on
10092,
of gears
e
Required
diffraction
on
100%
of gears
of and
diffraction
cent
allydrogen
percent
by
e
gears
Preparatory to selecting the material for the gear case, consider the effect on the gear alignment, clearances,and backlashof the relative gearand gear-casedeflections asgoverned by the elastic modulus andthermal expansion coefficient of the intended gear-casematerial. Determine the resulting changes in center distance and backlash, and choose another .materialif the results aredetrimental to gearoperation or gearlife.
3.4
FABRICATION Gear
fabrication
limit
gear life.
The recommended table XXIV and
3.4.1
and
process
fabrication techniques, in sections 3.4.1 through
controls
processes, 3.4.5 that
shall
minimize
and process follow.
conditions
controls
that
are summarized
in
Forging
Material Forgings Either should
processes
grain
should
orientation
be used
shall follow
to produce
approximately
gear blanks
bar stock or forgings may be used be used for grade 2 gears. Accurate
the finished
for all turbopump
gear outline.
power
train
gears.
for accessory gears. Open- or closed-die forgings closed-die forgings are needed for grade 3 gears.
High-energy-rate forgings of gear bodies complete with forged teeth are preferred for grade 4. All main-power gears for turbopumps should be grade 3 or better and should be made from forging blanks in which the direction of grain flow is controlled. These forgings Should contain no laps, voids, or banding. The forging supplier and the dies used should be qualified and figure
approved.
The
grain
flow
required
in the
cross
section
of a typical
forging
23.
q_
Center
line of finished
I
Grain
flow
Figure 23. - Cross-section
sketch of a forging
grain flow.
86
showing
proper
gear
is shown
in
3.4.2
Tooth The
tooth
without Hobbing clearance
cutting
reducing
is the must
components required
gears.
Green finish.
20 pitch
method
shall
gear load
capacity.
axial
undercut,
and
grinding Gears
Should
space
finer
20 pitch
before
should
3.4.3
be allowed
Use
stock
be used
than
be precut
is limited.
grinding
should
more complete discussion of manufacturer must coordinate time
satisfy
the
gear
configuration
preferred cutting method because it produces exist for the cutter. Shaping should be used
where
radii, root
Cutting
short-pitch
at the form
for
hobs
can be ground
to
diameter
work-hardening
gear grinding.
a good to cut
from
and
testing
an uncut
optimum
fillet
turbopump
gears
10 (chapters
and
axial other
for obtaining
blank;
reference
of cutters
obtain
and
tooth cutting and tool desagn. The and approve the tool form and cutter
for procurement
finish; however, gear teeth near
for specialized
metals
Consult
requirements
a good
coarser 5 and
than
6) for a
gear designer and the design. Sufficient lead
grinding
forms.
Heat Treatment
The
heat
without The
gear
any
machining
treatment inducing
blank,
of
gears
shall
produce
the
material
properties
required
defects.
whether
bar
or forging,
should
be normalized
at 1700 ° to
1750 ° F before
is started.
The
proper
material
properties
after
tooth
cutting.
Areas
listed
where
in section
hardening
3.3.1.2 is not
should
desired
be obtained should
be
by
masked
carburizing by
copper
plating. The
pack-type
carburizing
furnace furnace with on carburized
dew-point-control, 3 if control
and
pit-type timing
recommended
for
carburizing
infrared
analyzer
potential gradient For
critical
at the and
to gears,
for end
most
control. of the
minimize choose
Duplex cycle retained
only
is
not
recommended
an infrared samples
gears
and
a gear manufacturer
87
gear
stainless-steel
processes
be employed
austenite
any
grade.
A
gas control may be used through grade is very strict. The type of furnace
is a vacuum-retort
carburizing
should
for
that
reduce
to obtain
carbide
the
networks
experienced
type
the
desired near
in carburizing
the
with
an
furnace
carbon
carbon
content
outer
surface.
procedures.
3.4.4
Tooth
Finishing capacity. The
operations
copper
where
Finishing
place
that
is used
it is unwanted
introduces
the
The
tolerances
close
hardening, process
after
to mask
should
potential
be
of
loaded
for
accessory
Highly loaded accessory area after hardening.
may
zones. honing
Zone A, the if allowed)
active should
and
thus
grinding
prevent not
usually
require
profiles from
this
the
not
reduce
gear
carburization involving
in the
acid,
be ground
pattern
tooth.
a finishing
hardening
distortion.
areas
because
acid
in the root
for an external
velocity should
should
gear.
The
after
Grinding
honing
may
is the
be
,oed
on
is below 20 000 ft/min. not be etched to obtain
to maintain
gears
operation
process.
Abrasive
main-power-train
profile, is the be performed.
tip of the
shall
a process
risk is low and if the pitchline for turbopump gears. Teeth
and
the
the
gear
correcting
gears
15 illustrates
toward
by
resulting
gears
Figure
diameter
gear
on
accessory gears if the scoring Lapping is not recommended profile or lead modification. Lightly
the
hardening
embrittlement.
distortion
recommended
and
removed
for hydrogen necessary
because
carburizing
a good
not
tooth
be ground
tooth
contour. in the
is divided
into
root
three
area in which the finishing operation (grinding or Zone C extends a distance C from the root
The
distance
C may
be computed
as
0.250
C-
Pd
Zone
C is the
gears. but
Zone not
gears
specified
in which
B, which
required.
zone B can figure 15. For
zone
result
The
finishing
lies between transition
of
material
quality
for
undercut
and
The values to be specified values for a material grade
Zones from
in a mismatch
that
grades blend
operations
and
A and the
should
not
C, is the
finished
zone
the
3 and
4, it is recommended a minimum
depend on the application 3 gear in the 8- to 12-pitch
88
in which
profile
takes
that
form
tooth
be performed
of undercut
value and range
on highly finishing
to the
that
is allowed
unfinished
or blend
the manufacturing are as follows:
root
in
as illustrated
maximum
be specified
loaded
for blend plan.
values
in
be
radius. Typical
Undercut (maximize in the rangeof) .........
0.005 to 0.007 in.
Blend (maximize up to) ...................
0.002 in.
Blend radius (minimize in the rangeof) .......
0.020 to 0.030 in.
The amount of metal removed from the carburizedareasof the tooth should not exceed20 percent of the total casedepth available.Table XVI givesrecommendedmaximum values for grinding stock. It is recommendedthat the amount of material ground away after hardening always be kept to the minimum that allows the gear to meet the dimensional tolerances. Procedurespresentedin reference 44 should be followed in inslJectingthe gear for alteration of surfacetemper by the finishing process.
3.4.5
Shot Peening
Residual
compressive
surfaces Shot
peen
subject the
stress
to cyclic
tooth
root,
necessary
tensile
rim,
and
for
maximum
fatigue
life shall
exist
in gear
stresses. web
surfaces
of turbopump
power
gears.
The
location
peening and the direction of the shot stream should be clearly specified. In peening roots, the shot stream should be directed radially inward toward the gear center. MIL-S-13165 accurate
size
control
methods
control shot
to
should
of be
the inspection
specified
is recommended; should
not
shot-peening for
process.
shot-peening
to eliminate
hardness
be greater
1/2
be 42
nor
exist.
performance
to 55 on
less
control
quality
human
should
than
Process
than
checked
continuously
during
Rockwell
1/4 of the
requirements
for the
processing.
Automated
variability.
the
fillet
per MIL-S-13165 is recommended for rocket-engine-gear tooth 0.038 in. and larger. For radii of 0.025 to 0.030 in., use number be
is required,
Undersize
tooth Invoke since
no
shot-peening Round
C scale. radius.
of
cast
steel
Nominal
Number
shot
130 shot
roots with fillet radii of 110 size shot. Shot should
and
broken
shot
should
be
eliminated. Shot-peening an Almen root To
strip
should ensure
fillet
area),
heat-treatment should
arc height
be specified proper
shot
the
entire and
be confined
of 0.015A (in gin.
peening gear
pregrind to profile
Multipeening
(peening
the maximum
beneficial
roots
the
of turbopump
with
AA)
an exposure
before
of critical
tooth
and
areas
including
same
residual
surface
(the
most tip,
noncritical with
compressive
areas
89
size 35).
root
should
shot)
and
specify
roughness
area
complete. (sides
should
as shown
important
are
(ref.
Surface
peening
and
different stress
of 4×.
shot
operations
and
of 8 to 12 pitch
time
after
sides,
manufacturing finishing
gears
in the
in table
is the
be peened Subsequent
XIX.
tooth-root after
all
grinding
tip).
should
be used
to obtain
Rim and web surfitces should be shot peened perpendicular to the web surface: use as control an Almen strip height of 0.010A to 0.015A with an exposuretime of 4X (ref. 34). Surface
roughness
3.4.6
after
Configuration
hzformation
)br
manufacturing
necessary information
to
Sketches
configuration
should
be
instrument
allowable
main-power
on
drawing
AA.
shall
be fully
descriptive
of gear
added
to the Table
traces
deviations,
and
gear XI
showing
tolerance
drawing is
an
required bands
to present e:_ample
involute
should
information of
data-block
profile
be made
and
part
lead
of the
gear
gears, detailed
where
grinding
dimensional
of fillets
sketches
and
of the
roots
fillets
is not and
permitted,
roots
include
5 to 10 times
size
15).
Hardness
3.5
test
locations
should-be
indicated
on the drawing.
TESTING
3.5.1
Acceptance
The not Use
have
only
Rockwell met taken
a detrimental hardness
C scale
anywhere
performed to the
effect
may
and
be used
on an actual from
tooth the
tested
part depth
section. outer
acceptance
of
processing
On
surface
hardness
for testing
destructively Case
to
and
to measure
on the uncarburized sample.
prior
material
the
gears
shall
requirements
but
shall
on the gears.
indentor
hardness
samples
or on a test distance
tests
conformance
a 15N
heat-treat
gear,
Testing
quality-assurance
denzonstrate
the
125 gin.
fig. 13).
For ground
on
of gear
block
measuring
(e.g.,
gear
exceed
control the gear configuration. for two types of turbopump gears.
modifications,
the
not
Control
control
data
of
drawing
should
requirements.
A supplementary
(fig.
peening
of the should
at the
core hardness
gears. sample
Core gear,
be established
a carburized
gear,
to
at
the
50 R c .
9O
point
pitch
line
of the
or for testing
hardness
the
case
which
the
depth hardness
must
removed
a hardness
teeth.
case hardness
requirements
on a section by
gear
from
traverse has
a test
(fig.
is considered decreased
be 17)
to be to
Retained austenite content of accessoryand medium power gearsshould be measuredby either visual examination or X-ray diffraction. In casesof conflict, the meastlrementsmade by X-ray diffraction should be used. The austenite content of critical gears such as main-power turbopump gearsshould alwaysbe measuredby X-ray diffraction. Grain sizeshould be determined by the methods noted in ASTM E-112-63. All gears intended for further service should be magnetic-particle inspected per MIL-M-11472, and those with flaws should be rejected.
3.5.2
Performance
Performance actual
The
shall
turbopump
In all tests operated
tests
full
following
verify
operating
conducted at
Testing that
to demonstrate
speed
series
while
the
loaded
of tests
the
gear
system
will
operate
satisfactorily
at
conditions.
by
adequacy
of a new
design,
water
brake,
leaking
seal,
dynamometer,
the
gear train
should
or back-to-back
be
tester.
is recommended:
(1)
Short
run,
low load
(2)
Short
run,
full load
(3)
Full
duration,
(4)
Required
(5)
Ten-percent
(6)
Ten-percent
(7)
Lubricant
(8)
Simulated
full load
qualification
life
overload,
qualification
overload,
duration
flow
life to failure
limits
failure:
plugged
lubrication
jet,
or other
realistic
failure
modes. After the
any gear
design
modifications
evaluation
should
gears after condition
testing usually
examination The
use
problems Gear
tests
following
that
be
through
back-to-back may
should
continued
by
the
back-to-back
by
observation
test
of test
in turbopump hot-fire and static engine can be monitored throughout the test
of the gears of the
indicated
become be
the test
apparent
conducted
lubricant
jet
arrangement after with
mounting also
the gear
instrumentation
parameters:
91
port
series data
incorporated,
examination
runs. series
Gear tooth by periodic
in the
gear case.
is recommended
system
and
are
for
trouble
of
surface visual
shooting
is operational. adequate
to measure
accurately
the
(1)
Shaft
(2)
Lubrication Flow
speed
(input system: rate
Inlet
temperature
Outlet Inlet
temperature pressure
Individual
(3)
Bearing
(4)
Vibration. major
or output).
to distribution
jet pressures
temperatures -
One
manifold
for critical
on critical sensitive
vibration.
However,
jets.
bearings.
accelerometer if
located
resonances
accelerometers located close to the support greater aid in locating incipient problems.
(5)
Shock
intensity.
-
A shock
pulse
meter
are
anywhere expected,
bearings
or other
on the the
for each
tuned
case will detect use
shaft
response
of
multiple
in question
meter
is a
can be of
great aid in discovering bearing fatigue or similar trouble as it develops. Stopping the test prior to failure will prevent extensive damage that might otherwise mask the actual cause of the failure. (6)
Prime mover torque. load, heat generation,
(7)
Audible may
alert
sound.the
test
- This variable often or other degradation
Change crew
in pitch
to watch
often
other
92
may be the first of gear condition. accompanies
parameters
closely.
criterion
a developing
of increasing
trouble
and
APPENDIX Conversion
of U.S. Customary
Units
to SI Units
SI unit
Conversion
kgf
N
9.807
lbf
N
4.448
ft
m
0.3048
in.
cm
2.54
Physical quantity
U.S. customary
Force
Length
A
unit
25.4
mil Mass
Ibm
kg
0.4536
Power
hp
W
745.7
Pressure
mm Hg
N/m 2
133.3
psi (lbf/in. 2)
N/m 2
6895
rpm
rad/sec
0.1047
Rotational
speed
factor a
Btu
J
lbm.°F
kg-K
Stress
psi (lbf/in. 2)
N/m 2
6895
Temperature
oF
K
5 K = - (°F ÷ 459.67) 9
Tensile strength
psi (lbf/in. 2)
N/m 2
6895
Thermal
Btu
J
1054
Torque
in.4bf
N-m
0.1130
Viscosity
centistokes
m 2/sec
1.00xl0 -6
Volume
gal
m 3
3.785x10
Specific heat
aMultiply
energy
value
4184
given m U.S. customary
unit
by conversion
factor
to obtain
-3 equiva-
lent value in SI unit. For a complete listing of conversion factors, see Mechtly, E.A.: The International System of Units. Physical Constants and Conversion Factors.
Second
revision,
NASA
SP-7012,
1973.
93
94
APPENDIX
B
GLOSSARY Symbol
Definition
AA
arithmetic
a
addendum
D
pitch diameter
Db
base circle diameter
Do
outside diameter
d
(1) dedendum (2) pitch diameter of pinion (3) overhang (fig. 3)
db
base circle diameter
do
outside diameter
EP
extreme
F
face width of gear
h
lubricant
ht
tooth whole depth (total
J
geometry
K
tooth pitting index compressive stress)
average
of gear of gear
of gear
of pinion
of pinion
pressure
film thickness depth)
factor for bending
strength
(preliminary
m
modifying
factor
Ko
modifying
factor for overload
modifying
factor for size
Kt
modifying
factor for temperature
Kv
modifying
factor for dynamic
K
95
for load distribution
toad
design
value
representative
of
Definition
S__ymbol mG
gear ratio
P
pitch; Hertz contact
pressure number
diametral
of teeth
pitch, Pd = pitch diameter,
in.
PA
pressure angle
PLV
pitchline
PV
scoring index, defined
in note on Table V
PVT
scoring index, defined
in note on Table V
ppi
pounds per inch (of face width)
Rc
hardness
ref.
dimension
S
bearing span
Sac
allowable
Sc
compressive
Stu
ultimate
Sty
yield tensile strength
s
surface roughness
t
tooth thickness
TIF
true involute
UL
unit load (preliminary
Wt
total tangential
Y
tooth form factor
velocity
on Rockwell
"C" scale
given for reference
compressive
only; not to be measured
stress
stress
tensile strength
form design value representative
tooth load
h/s
96
of bending
stress)
Symbol
Definition
15N
hardness scale for the superficial Rockwell 15N scale results in a very small indentation)
Material
hardness
test (use
of the
Identification
A356-T61
high-strength
A357-T61
high-strength cast aluminum developed by careful control T61
AISI 410 440C
AISI designations
for corrosion-resistant
AISI 3310 4140 4340 4620
AISI designations
for low-alloy carbon
cast aluminum
alloy, temper
T61
alloy in which special properties of casting and chilling techniques;
hardenable
can be temper
steels
steels
8620 9310 9315 AMS5630
wrought
corrosion-
AMS 6260 6265 6470
wrought
low-alloy
Berylco 25
beryllium-copper
carburizing
steel
and heat-resistant
steel per AMS 5630
steels per AMS 6260, 6265, and 6470 respectively
alloy made by Kawecki
low-carbon-content
steel
that
Berylco Industries,
can be treated
to cause
Inc. the
metal
to
absorb carbon into the surface, thereby increasing surface hardenability while maintaining a weaker, softer, but tougher core CRES
corrosion-resistant
GH2
gaseous hydrogen
Inconels
trade name of International
IRFNA
inhibited
LH2
liquid hydrogen,
steel
Nickel Co. for austenitic
red fuming nitric acid, propellant propellant
97
nickel-base
grade per MIL-P-7254
grade per MIL-P-27201
alloys
Identification
Material LO2, LOX
liquid oxygen,
N2 H4
hydrazine,
N2 04
nitrogen
tetroxide,
nital
solution
of concentrated
nitriding
steel
propellant
propellant
grade per MIL-P-25508
grade per MIL-P-26536
propellant
grade per MIL-P-26539
nitric acid in alcohol
steel alloyed with nitride-forming chromium, molybdenum, vanadium,
elements such as aluminum, and tungsten. Exposure of the
alloy to active nitrogen results in a thin hard case that is especially wear resistant. Precautions are necessary to avoid chipping. Cost is higher than that for carburizing. Oronite
262
zinc dialkyl dithiophosphate Co.
additive,
Oronite
Div., Chevron
RP-1
kerosene-base
fuel, propellant
grade per MIL-P-25576
Tens-50
high-strength
aluminum
UDMH
unsymmetrical
Chemical
alloy for casting
dimethylhydrazine,
propellant
grade
per MIL-P-25604
Title
Specification Materials 1 AMS 3132
Varnish,
Synthetic
AMS 3170
Thinner,
Alcohol-Ester
AMS 5630
Bars and Forgings - 17 Cr-0.5 Mo (0.95-1.20
AMS 6260
Bars,
Forgings,
(0.07-0.13 AMS 6265
Bars,
AMS 6470
C).
Mech.
Tubing-3.25
Ni-l.2
Cr-0.12
Mo
and
Mech.
Tubing-3.25
Ni-1.2
Cr,0.12
Mo
C) Premium
Quality
C)
Bars, Forgings, (0.38-0.43
Preventive.
and
Forgings,
(0.07-0.13
Resin Corrosion
Consumable
and Mech. Tubing,
Nitriding-
Electrode
Vacuum
1.6 Cr-0.35
Melted.
Mo-1.13
A1
C)
1Specifications designated AMS are published by Society of Automotive Engineers, Inc., 2 Pennsylvania Plaza, New York, NY 10001. Military specifications are published by the Department of Defense, Washington, DC 20025.
98
Title
Specification Materials
MIL-C-16173 MIL-L-6081
Corrosion (ASG)
Preventive
Compound,
Solvent
Cutback,
Lubricating
Oil, Jet Engine,
MIL-L-6086
Lubricating
Oil, Gear, Petroleum
Base.
MIL-L-7808
Lubricating
Oil, Aircraft
Engine, Synthetic
MIL-L-25336
Lubricating Strength.
Oil, Aircraft
MIL_-25576
Propellant,
Kerosene.
MIL@-27401
Propellant
Pressurizing
Agent, Nitrogen.
Propellant
Pressurizing
Agent, Helium.
MIL-P-27407
(USAF)
Processesand
Test Methods
Turbine Turbine
Engine,
ASTMD-2596-69
Extreme-Pressure Properties of Lubricating Measurement of. ASTM 17 (1969).
ASTME112-63
Estimating
Federal
Test Method
No. 791, Method Federal
Test Method
No. 791, Method
Std.
6508.1
MIL-C-26074 MIL-M-11472
Std.
6503.1
Base.
Synthetic
Base, High Film
Grease (Four Ball Method),
Grain Size of Metals. ASTM, 1963.
Load Carrying Capacity (Mean Hertz Load). Jan. 15, 1969. Contained in FTM Std. No. 791B, Change Notice 1, Oct. 15, 1969. Load Carrying Capacity of Lubricating Oils (Ryder Gear Machine). Jan. 15, 1969. Contained in FTM Std.No. 791B, Change Notice 1, Oct. 15, 1969. Coatings,
(ORD)
Cold-Application.
Electroless
Nickel, Requirements
Magnetic Particle Inspection;
MIL-S-13165
Shot Peening
QQ-C-320a (FederalSpecification)
Chromium
Process for Ferromagnetic
of Metal Parts.
Plating (Electrodeposited).
99
for. Materials.
Identification
Vehicles, Pumps, and Engines Agena
upper
stage
for
Atlas
and
Thor
launch
vehicles;
uses LR81-BA-11
engine Atlas (SLV-3)
launch
vehicle
vernier,
using
MA-5
and 1 sustainer
engine
engines;
system
boosters
containing
provide
2 booster,
2
330 000 to 370 000
lbf thrust; sustainer, 60 000 lbf thrust; uses LOX/RP-1 ; engine system manufactured by Rocketdyne Division, Rockwell International Corp.
Centaur
high-energy
upper
stage for Atlas
and Titan
launch
vehicles;
uses 2
RL10 engines H-1
engine
for S-IB; 200 000 lbf thrust;
uses LOX/RP-1
; manufactured
by
Rocketdyne LR81-BA- 11
engine for Agena upper stage; 15 000 lbf thrust; uses IRFNA/UDMH; manufactured by Bell Aerospace Company, Division of Textron
LR-87-AJ-5
Aerojet
engine
for the first stage of the Titan II; uses N_O4/A-50*
and
develops 215 000 lbf thrust LR-91-A J-5
Aerojet
engine
and develops
for the second
stage of the Titan
II; uses N204/A-50*
100 000 lbf thrust
Mark 3
turbopump for the engines in the Atlas, Thor, manufactured by Rocketdyne
Mark 4
turbopump
for
the
Atlas
sustainer
and Saturn IB boosters;
engine;
manufactured
by
Rocketdyne RL10
engine for Centaur upper stage; manufactured by Pratt & Whitney
15 000 lbf thrust; uses LOX/LH2; Aircraft Division of United Aircraft
Corp. S -IB
first stage (booster)
of the Saturn IB vehicle; uses a cluster
of eight H-1
engines Thor
launch
vehicle
LOX]RP-1; Titan Ii
launch
using
MB-3 engine
system;
engine system manufactured
vehicle
engines developed
using
the
by Aerojet
"50[50 mixture of UDMH and hydrazine.
100
LR-87-AJ
170 000
lbf thrust; uses
by Rocketdyne and
Liquid Rocket
LR-91-AJ Co.
series of rocket
Abbreviation AGMA AISI AMS ASA ASLE ASME ASTM SAE
Identification American
Gear Manufacturers
Association
American
Iron and Steel Institute
Aerospace
Material Specifications
American
Standards
American
Society
of Lubrication
American
Society
of Mechanical
American
Society
for Testing
Association
Society of Automotive
101
(published
Engineers Engineers
and Materials
Engineers
by SAE)
C'q
REFERENCES 1. Anon.: Terms, Definitions,
Symbols,
2. Dudley,
D. W., ed.: Gear Handbook.
3. Anon.:
Design Procedure
411.02, 4.
and Abbreviations. McGraw-Hill
for Aircraft
Engine
AGMA 112.04, AGMA, Aug. 1965.
Book Co., '1962. and Power
Take-Off
Spur and Helical Gears. AGMA
AGMA, Sept. 1966.
Anon.: AGME Gear Handbook. Vol. 1 - Gear Classifications, Unassembled Gears. AGMA 390.03, AGMA, Jan. 1973.
5. McIntire,
W. L.; and Malott,
R. C.: Advancement
Materials,
and Measuring
of Spur Gear Design Technology.
Methods
for
USAAVLABS
Tech. Rep. 66-85, U.S. Army Aviation Lab. (Fort Eustis, VA), 1966. 6. McIntire,
W. L.; and Malott,
R. C.: Advancement
Tech. Rep. 68-47, U.S. Army Aviation
of Helical Gear Design Technology.
Lab. (Fort Eustis, VA), 1968.
7. Coleman, W.; Lehmann, E. P.; Mellis, D. W.; and Peel, D. M.: Advancement Bevel Gear Technology. USAAVLABS Tech. Rep. 69-75, U.S. Army Aviation Oct. 1969. 8. Anon.:
Information
225.01, 9.
Sheet
for Strength
of Spur, Helical, Herringbone
J. B.; and Dudley,
D. W.: Results
Teeth. J. Eng. Ind. Trans. ASME, SeriesB, D. W.: Practical
of 15-Year Program
12. Costomiris, PWA-3718, 13. Bodensieck,
14. Anon.!
and Bevel Gear Teeth.
AGMA
of Flexural
Fatigue Testing
of Gear
vol. 86, 1964, pp. 221-239.
Gear Design. McGraw-Hill
11. Anon.: Information Sheet for Surface Durability Gear Teeth. AGMA 215.01, AGMA, Sept. 1966.
presented
of Straight and Spiral Lab. (Fort Eustis, VA),
AGMA, Dec. 1967.
Seabrook,
10. Dudley,
USAAVLABS
Book Co., 1954. (Pitting)
of Spur, Helical, Herringbone,
and Bevel
G.; Daley, D.; and Grube, W.: Heat Generated in High Power Reduction Gearing. Pratt & Whitney Aircraft Div., United Aircraft Corp. (East Hartford, CT), June 1969. E. J.: Specific at 1965 Aerospace
Information
AGMA 217.01,
Film Thickness
-An
Index
of Gear Tooth
Surface
Gear Comm. Tech. Div. Meeting, AGMA (Denver,
Sheet - Gear Scoring Design Guide for Aerospace
Deterioration.
Paper
CO), Sept. 1965.
Spur and Helical Power Gears.
AGMA, Oct. 1965.
15. Borsoff, V. N.; and Gode t, M. R.: A Scoring 147-153.
Factor
103
for Gears. ASLE Trans., vol. 6, no. 2, 1963, pp.
16. Lemanski,A. J.: A Comparison of GearScoringIndices.VertolDiv.,BoeingCo.(Morton,PA),Feb. 1965. 17. Hartman,M. A.: Advancesin Aerospace PowerGears.PowerTransmission
Design,
vol. 9, no. 11,
Nov. 1967, pp. 40-47.
18. Butner,
M. F." Propellant Lubrication Properties Pts. I and II (AD 259143), June 1962.
19. Lorvick, R. R.: Lubricating
Investigation,
Final Report.
Rep. WADD-TR,61-77,
Gears. Mach. Des., vol. 42, no. 17, July 1970, pp. 108-117.
20.
McCain, J. W.; and Alsandor, E.: Analytical Aspects of Gear Lubrication on the Disengaging Side. ASLE paper 65-LC-16, ASLE and ASME Lubrication Conf. (San Francisco, CA), Oct. 18-20, 1965.
21.
McIntire, W. L.: How to Reduce (Indianapolis, IN), Feb. 1964.
22. Dudley,
Gear
Vibration
W. M.; and Hall, Ira K., Jr.: Analysis
Failures.
of Lateral
Allison
Vibrations
ASME paper 66-MD-4, ASME Design Eng. Conf. and Show (Chicago, 23.
Reiger, 1964.
24.
Anon.: Tooth Proportions AGMA, Aug. 1968.
25.
Anon.: Tooth Proportions for Fine-Pitch 207.05, AGMA, June 1971.
N.: Vibration
Characteristics
of Geared
for Coarse-Pitch
Transmission
Involute
Involute
Div.,
General
Motors
of Gears and Rimmed
28.
Wheels.
IL), May %12, 1966.
Systems.
AGMA
109.14,
Spur Gears (ANSI B6.1-1968).
AGMA, Oct.
AGMA 201.02,
Spur and Helical Gears (ANSI B6.7-1967).
26. Dolan, T. J.; and Broghamer, E. I.: A Photoelastic Study of the Stresses in Gear Tooth of Illinois Eng. Expt. Sta. Bull. 335, Univ. of Illinois (Urbana, IL), Mar. 1942. *27.
Corp.
AGMA
Fillets. Univ.
Hartman, M. A.: Profile Modification for Heavily Loaded Gears Under Dynamic Conditions. Rocketdyne Div., North American Rockwell Corp. (Canoga Park, CA), Nov. 1967 (unpublished). Pollack, C.: Better 1968, pp. 78-80.
Surface
Lavoie, F. J.: High Velocity
Integrity
- Secret
of Part Reliability.
Machinery,
vol. 75, no. 3, Nov.
Forging of Gears. Mach. Des., vol. 40, no. 28, Dec. 1968, pp. 146-151.
Burroughs, L. R.; and Fitzgerald, P. C.: Evaluation of Advanced Gear Forging Techniques. USAAVLABS Tech. Rep. 69-11, U.S. Army Aviation Lab. (Fort Eustis, VA), Apr. 1969.
*Dossier
for design
available
for inspection
criteria
monograph
at NASA
Lewis
"Liquid Research
Rocket Center,
Engine
Turbopump
Cleveland,
104
Ohio.
Gears."
Unpublished.
Collected
source
material
31. Parkinson,F. L.: Evaluationof High-Energy-Rate ForgedGearsWithIntegralTeeth.
USAAVLABS
Tech. Rep. 67-11, U.S. Army Aviation Lab. (Fort Eustis, VA), Mar. 1967. 32. Anon.:
Recommended
Procedure
for Carburized
Industrial
Gearing.
AGMA 246.01A,
AGMA, Nov.
1971. 33. Straub,
J. C.: Shot Peening
34. Anon.:
Shot Peening. Wheelabrator
35. Anderson, Utilization 36.
Bush, J.
in Gear Design,
1964. AGMA 109.13,
Corp. (Mishawaka,
AGMA, June 1964.
IN), 1965.
B. N.; and Hartman, M. A.: Multipeening of Surfaces To Extend Fatigue Life. Technology Docket NAR 50477, Rocketdyne Div., North American Rockwell Corp., Mar. 1966. J.;
Mattson,
R. L.; and Roberts,
J. G.: Shot Peening
Treatments.
U.S. Patent
3,073,022,
assigned to General Motors Corp., issued Jan. 1963. 37.
Anon.:
Turbopump
Monograph,
Systems
for
Liquid
39. Buckingham, Campbell,
41.
Anon.:
Engines.
NASA
Space
Vehicle
Design
Criteria
NASA SP-8107 (to be published).
38. Anon.: Liquid Rocket Engine Turbopump NASA SP-8048, Mar. 1971.
40.
Rocket
E.: Analytical
Mechanics
Bearings. NASA Space Vehicle
of Gears. McGraw-Hill
Book Co., 1949.
M. E.; Loser, J. B.; and Sn_egas, E.: Solid Lubricants.
Maag Gear Book. Maag Gear Wheel Co. (Zurich,
Design Criteria Monograph,
NASA SP-5059, May 1966.
Switzerland),
Dec. 1965.
J
42. Sigg, H.: Profile _nd Longitudinal 43. Lyman, Society 44. Anon.:
T., ed.: Metals Handbook.
C6rrections
on Involute
Vol. 1: Properties
Gears. AGMA
and Selection
109.6, AGMA, Oct. 1965.
of Metals.
for Metals (Metals Park, OH), 1961. Surface Temper
Inspection
Process. AGMA 230.01,
105
AGMA, Mar. 1968.
Eighth ed., American
106
NASA SPACE VEHICLE DESIGN CRITERIA MONOGRAPHS ISSUED TO DATE
ENVIRONMENT SP-8005
Solar Electromagnetic
SP-8010
Models of Mars Atmosphere
SP-8011
Models of Venus Atmosphere
SP-8013
Meteoroid Environment March 1969
SP-8017
Magnetic
SP-8020
Mars Surface Models (i968),
SP.8021
Models of Earth's
SP-8023
Lunar Surface Models, May 1969
SP-8037
Assessment
and Control
of Spacecraft
SP-8038
Meteoroid
Environment
Model-1970
October
Radiation,
Fields-Earth
Revised May 1971
(1967),
May 1968
(1972),
Revised September
Model-1969
(Near
and Extraterrestrial,
Earth
1972
to Lunar
Surface),
March 1969
May 1969
Atmosphere
(90 to 2500 km), Revised March
Magnetic
Fields, September
(Interplanetary
1973
1970
and Planetary),
1970
SP-8049
The Earth's
Ionosphere,
March 1971
SP.8067
Earth Albedo and Emitted
Radiation,
July 1971
SP-8069
The Planet Jupiter
December
1971
SP.8084
Surface
(1970),
Atmospheric
Extremes
(Launch
and Transportation
Areas),
May 1972 SP-8085
The Planet Mercury
(1971),
SP-8091
Thd Planet Saturn (1970),
June 1972
SP_8092
Assessment June 1972
of Spacecraft
and Control
107
March 1972
Electromagnetic
Interference,
SP-8103
ThePlanetsUranuS , Neptune , andPluto(1971),November 1972
SP-8105
Spacecraft
•'
Thermal
.
:
Control,
May 1973
STRUCTURES •
SP-8001
Buffeting
SP-8002
Flight-Loads
SP-8003
Flutter,
SP-8004
Panel Flutter,
Revised June 1972
SP-8006
Local Steady
Aerodynamic
SP-8007
Buckling of Thin-Walled
SP-8008
Prelaunch
Ground Wind Loads, November
SP-8009
Propellant
Slosh Loads, August 1968
SP-8012
Natural
SP-8014
Entry Thermal
SP-8019
Buckling of Thin-Walled
Truncated
SP-8022
Staging Loads, February
1969
SP-8029
During Atmospheric
Ascent, Revised November
Measurements
During
Buzz, and Divergence,
Vibration
Aerodynamic May 1969
Launch
Circular Cylinders,
August
and Rocket-Exhaust
1965
1968
Cones, September
Heating
SP-8031
Slosh Suppression,
SP-8032
Buckling of Thin-Walled
SP-8035
Wind Loads During Ascent, June. 1970
SP-8040
Fracture
SP-8042
Meteoroid
SP-8043
Design-Development
Excitation,
1968
During Launch
February
1969
May 1969 Doubly
Curved Shells, August
of Metallic Pressure Vessels, May 1970
108
1968
1968
Transient
Damage Assessment,
1964
and Exit, May 1965
Revised August
September
SP-8030
Control
and Exit, December
Loads During Launch
Loads From Thrust
1970
July 1964
Modal Analysis,
Protection,
,
May 1970
Testing, May 1970
1969
and Ascent
SP-8044
Qualification Testing,May1970
SP-8045
Acceptance Testing,April 1970
SP-8046
LandingImpactAttenuationfor Non-Surface-Planing Landers,April 1970
SP-8050
StructuralVibrationPrediction,June1970
SP-8053
NuclearandSpace RadiationEffectsonMaterials, June1970
SP-8054
SpaceRadiationProtection,June1970
SP-8055
Preventionof CoupledStructure-Propulsion Instability(Pogo),October 1970
SP-8056
FlightSeparation Mechanisms, October1970
SP-8057
StructuralDesignCriteriaApplicableto aSpaceShuttle,Revised March 1972
SP-8060
Compartment Venting,November 1970
SP-8061
Interactionwith UmbilicalsandLaunchStand,August1970
SP-8062
EntryGasdynamic Heating,January1971
SP-8063
Lubrication,Friction,andWear,June1971
SP-8066
Deployable Aerodynamic Deceleration Systems, June1971
SP-8068
BucklingStrengthof StructuralPlates,June1971
SP-8072
AcousticLoadsGenerated by thePropulsionSystem,June1971
SP-8077
Transportation andHandlingLoads,September 1971
SP-8079
StructuralInteractionwithControlSystems, November1971
SP-8082
Stress-Corrosion Crackingin Metals,August1971
SP-8083
DiscontinuityStresses in MetallicPressure Vessels, November1971
109
SP-8095
PreliminaryCriteria for the Fracture Control of SpaceShuttle Structures, June1971
SP-8099
Combining AscentLoads,May1972
SP-8104
StructuralInteractionWith Transportationand HandlingSystems, January1973
GUIDANCE ANDCONTROL SP-8015
Guidance andNavigation for EntryVehicles,November 1968
SP-8016
Effectsof StructuralFlexibilityon Spacecraft ControlSystems, April 1969
SP-8018
Spacecraft Magnetic Torques,March1969
SP-8024
Spacecraft Gravitational Torques,May1969
SP-8026
Spacecraft StarTrackers, July 1970
SP-8027
Spacecraft RadiationTorques,October1969
SP-8028
EntryVehicleControl,November 1969
SP-8033
Spacecraft EarthHorizonSensors, December 1969
SP-8034
Spacecraft MassExpulsionTorques,December 1969
SP-8036
Effectsof StructuralFlexibility on LaunchVehicleControlSystems, February1970
SP-8047
Spacecraft SunSensors, June1970
SP-8058
Spacecraft Aerodynamic Torques,January1971
SP-8059
SpacecraftAttitude Control DuringThrustingManeuvers, February 1971
SP-8065
TubularSpacecraft Booms(Extendible,ReelStored);February1971
SP-8070
Spaceborne DigitalComputerSystems, March1971
SP-8071
Passive Gravity-Gradient LibrationDampers, February1971
SP-8074
Spacecraft SolarCellArrays,May1971
110
SP-8078
Spaceborne ElectronicImagingSystems, June1971
SP-8086
Space VehicleDisplaysDesignCriteria,March1972
SP-8096
Space VehicleGyroscope Sensor Applications, October1972
SP-8098
Effectsof StructuralFlexibility on Entry VehicleControlSystemg, June1972
SP-8102
Space VehicleAccelerometer Applications, December 1972
CHEMICALPROPULSION SP-8087
LiquidRocketEngineFluid-Cooled Combustion Chambers, April 1972
SP-8081
LiquidPropellant GasGenerators, March1972
SP-8109
Liquid RocketEngineCentrifugalFlowTurbopumps, December1973
SP-8052
LiquidRocketEngineTurbopumpInducers, May 1971
SP-8110
LiquidRocketEngineTurbines,January1974
SP-8048
LiquidRocketEngineTurbopumpBearings, March1971
SP-8101
Liquid RocketEngineTurbopumpShaftsandCouplings,September 1972
SP-8094
LiquidRocketValveComponents, August1973
SP-8097
LiquidRocketValveAssemblies, November1973
SP-8090
LiquidRocketActuatorsandOperators, May1973
SP-8080
LiquidRocketPressure Regulators, ReliefValves,CheckValves,Burst Disks,andExplosive Valves,March1973
SP-8064
SolidPropellantSelection andCharacterization, June1971
SP-8075
SolidPropellantProcessing Factorsin RocketMotor Design,October 1971
SP-8076
SolidPropellant GrainDesignandInternalBallistics, March1972
SP-8073
SolidPropellant GrainStructuralIntegrityAnalysis,June1973
111
SP-8039
SolidRocketMotorPerformance AnalysisandPrediction, May 1971
SP.8051
SolidRocketMotorIgniters,March1971
SP-8025
SolidRocketMotorMetalCases, April 1970
SP-8041
Captive-Fired Testingof SolidRocketMotors,March1971
,
1 12
NASA-Langley, 1974
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V
FOREWORD
NASA
experience
Accordingly,
has
criteria
indicated
are
a need
being
for uniform
developed
in the
criteria
following
for the
areas
design
of space
vehicles.
of technolgy:
Environment Structures
Individual are
components
completed.
monograph.
of this
This
Guidance
and Control
Chemical
Propulsion
work
document,
will be issued
part
of
A list of all monographs
the
issued
as separate
series
prior
on
monographs
Chemical
to this one
as soon
Propulsion,
can be found
as they
is one
such
final
pages
on the
of this document. These
monographs
are
except as may these documents,
be
uniform
practices
design
to be regarded
for NASA
management
written
by
International technical
was
Martin
A.
Corporation, accuracy
community
of
George
Corporation; Rocket
in detail.
Comments
concerning
National Office), March
Aeronautics Cleveland, 1974
edited
and
the and
Ohio
technical Space
44135.
by
Lionel
as NASA
requirements,
Pratt
B. Keller, engineers and
& Whitney
Buehler W. Drier
content Administration,
of this
Division,
Research
Research
To
the of
Center
the
text.
In
Aircraft of Aerojet
reviewed
will be welcomed Center
assure
technical
United
W. Heath
was
Rockwell
of Lewis.
review
William
monograph
Lewis
Jr.
throughout
Aircraft Lewis
monograph
Division,
critical
Corporation; of the
This
Rocketdyne
Russell and
was prepared under the Lewis Research Center;
Levinson.
Butner,
consultations,
of The Delmar
F.
scientists
of
Glover
Company;
monograph
was
and
Myles
document,
Costomiris H.
not
Turbopump Gears," Design Criteria Office,
Schmidt
and
in interviews,
H.
Wayne
and
vehicles.
Engine Chief,
Harold
and this
participated
particular, Liquid
by
Hartman
to design
project specifications. It is expecte_t, however, that may indicate to be desirable, eventually will provide
space
This monograph, "Liquid Rocket direction of Howard W. Douglass, project
as guides
specified in formal revised as experience
(Design
by
the
the
Criteria
For sale by the National Technical Springfield, Virginia 22151 Price -154.50
Information
Service
GUIDE The
purpose
of this monograph
significant
experience
programs firm
TO THE USE OF THIS
to date.
guidance
and
knowledge and assesses
achieving
greater
greater that
and
present,
accumulated
It reviews
for
product, and major sections
is to organize
MONOGRAPH
current
in
design
consistency
for effective development
practices,
in design,
efficiency in the design are preceded by a brief
and
in design,
and from
increased
effort. The introduction
use
the
operational
them
establishes
reliability
in the
end
monograph is organized into two and complemented by a set of
references. The
State
identifies
the
which
current best
of
Criteria, or
design.
Both
Criteria,
elements.
the
total
design.
When serves
a proper
be
Design
design
problem,
and
succinctly
the
is required,
the
It describes
detailed
information
as a survey
technological
Practices, the
imposed
of the
base
for
clearly
each
serve
procedure
subject
the
that
Design
provides
Criteria
and
3, state
to
the
what
rule,
guide,
element
to
assure
as a checklist
of rules
for the
its adequacy. how
to satisfy
when
Recommended
guidance
briefly
design
effectively
is described; The
and
essential
or in assessing
in section
provided. positive
3, state on
can
a design also
best are
in section
Criteria
in guiding
provide
have'been
similarly
Contents
design
discusses
this
cannot
Practices, practicing
each
of the
be done
concisely,
in conjunction
designer
on
criteria. with
how
the
to achieve
design:
sections
within
The
The
references
successful
in successful
in italics
must
to use
possible,
appropriate
the
shown
Recommended
Design
involved This section
prepares
standard
manager
Whenever
and
to these
are cited. and
reviews
Practices.
limitation,
The
pertaining
material
Design
project
2,
elementsare
references
Recommended
successful
section
design
tecnnology
available
background
The
Art,
numbered displays
can be followed design
specifications,
organized
criteria
this
decimally
numbered
subsections
correspond
from
continuity
of subject
in such
through
both
monograph
or a design
loosely organized its merit should
into
manual.
body of existing be judged on how
sections is not
as a discrete intended
It is a summary successful effectively
to
subsections section
to section.
a way
that
111
the subjects
The
format
a particular
for
aspect
of
a
of
subject. be
a
design
and a systematic
design techniques and it makes that material
to the designer.
so that
handbook,
ordering practices. available
of the
set
large
and
Its value and to and useful
CONTENTS Page
l.
INTRODUCTION
2.
STATE OF THE ART
3.
DESIGN CRITERIA
APPENDIX
A - Conversion
APPENDIX
B - Glossary
REFERENCES
and Recommended of U.S. Customary
Design Criteria Monographs
53
...............
Units to SI Units
93
............
95 103
Issued to Date
Speed Ratio Speed Capability Gear Type Gear Mounting Gear Attachment Backlash Load Capacity Root Bending Strength Face Compressive Strength
Chipping Resistance and Cooling
Heat Removal Scoring Prevention Lubricant Properties Lubricant Delivery System
......
107
.......
STATE OF THE ART
2.1
GEAR SYSTEM
Gear Case
Practices
...........................
SUBJECT
Lubrication
5
.........................
................................
NASA Space Vehicle
Tooth Tooth
1
...........................
6
DESIGN CRITERIA-
3.1
53
2.1.1 2.1.2 2.1.3
10 10 12
3.1.1 3.1.2 3.1.3
53 54 55
2.1.4 2.1.5 2.1.6 2.1.7
13 15 16 16
3.1.4 3.1.5 3.1.6 3.1.7
55 56 56 56
2.1.7.1 2.1.7.2 2.1.7.3
16 18 21
3.1.7.1 3.1.7.2 3.1.7.3
57 59 61
2.1.8
22
3.1.8
63
2.1.8.1 2.1.8.2 2.1.8.3 2.1.8.4
22 23 23 26
3.1.8.1 3.1.8.2 3.1.8.3 3.1.8.4
63 64 66 67
2.1.9
27
3.1,9
68
V
SUBJECT GEAR DETAIL Pressure Angle Number of Teeth Contact Ratio Face Width Tooth Proportions Whole Depth Tooth Thickness Addenda Root Fillet Tooth-Form Modification Surface Tolerances Surface Texture Rim and Web
STATE OF THE ART
CRITERIA
2.2
28
3.2
69
2.2.1 2.2.2
28 29
3.2.1 3.2.2
69 69
2.2.3 2.2.4 2.2.5
29 29 30
3.2.3 3.2.4 3.2.5
70 70 71
2.2.5.1 2.2.5.2 2.2.5.3 2.2.5.4 2.2.5.5 2.2.5.6 2.2.5. 7
30 31 31 31 31 33 35
3.2.5.1
71
3.2.5.2 3.2.5.3 3.2.5.4 3.2.5.5 3.2.5.6 3.2.5.7
72 72 73 74 75 76
2.2.6
36
3.2.6
77
3.2.6.1 3.2.6.2
77 80
Rim and Web Proportions Gear Resonance Tolerances
DESIGN
2.2. 7
37
3.2. 7
80
2.3
41
3.3
81
2.3.1
41
3.3.1
81
Material Grades
2.3.1.1
42
MetallUrgical Properties
2.3.1.2
43
3.3.1.1 3.3:1.2
83 83
2.3.2
43
3.3.2
84
2.4
44
3.4
86
Tooth Finishing
2.4.1 2.4.2 2.4.3 2.4.4
44 44 45 45
3.4.1 3.4.2 3.4.3 3.4.4
86 87 87 88
Shot Peening Configuration
2.4.5 2.4.6
46 48
3.4.5 3.4.6
89 90
2.5
49
3.5
90
2.5.1 2.5.2
49 50
3.5.1 3.5.2
90 91
MATERIALS Gears
Gear Case FABRICATION Forging Tooth Cutting Heat Treatment
Control
TESTING Acceptance Testing Performance Testing
vi
LIST OF FIGURES Title
Figure 1
Schematics
of gear arrangements
2
Relative
3
Gear mounting
4
Schematic
5
Method
6
Allowable
for mounting
Probability
8
Allowable
9
gear
and Saturn IB boosters)
.......
14 15
....................
vs root bending
quality grades
compressive
12
18
........................
of tooth breakage
four material
.........
stress vs cycle life for gears of
quality grades
of four material
velocity
9
13
(Atlas, Thor,
a detachable
root bending
of pitchline
.........
.........................
of Mark 3 turbopump
four material 7
in major operational _urbopumps
usage of gear types as a function methods
Page
stress for gears
19
.......................
stress vs cycle life for gears of
quality grades
20
........................
Probability of tooth pitting vs compressive stress for gears of four material quality grades .......................
10
Sketch illustrating
terms and symbols for tooth proportions
11
Addenda
12
Sketch illustrating
terms for gear surfaces
13
Sample inspection
charts for involute
14
Sketches
15
Sketch illustrating
16
Sketch
of gear arrangement
17
Sketch
showing locations
18
Sketch illustrating
19
Recommended
values for equal strength
illustrating
vs number
30
..........
of gear teeth (20 ° PA spur gears)
....
and lead
................. (original
grinding zones on critical hardened in a back-to-back
tip, edge, and end radii
34
and uprated gears
gear tester
for case depth and hardness
designs)
.....
............
tests
36 47
...........
51
............
62
..............
root fillet radii vs number of teeth (25 ° PA spur gears)
vii
32 33
...................
rim and web dimensions
gear-tooth
21
62 .......
73
Title
Figure 20
Acceptable
21
Sketches
22
Recommended
23
Cross-section
and unacceptable illustrating
recommendations
locations sketch
lead traces
for stock
of a forging
75
................... for design
removal showing
Page
of lightening
for balancing proper
Vlll
grain flow
holes
............. ............
........
78 79 86
LIST OF TABLES Page
Title
Table I II
Gear System
Gear Design Data for Major Operational
III
Characteristics
IV
Tooth
V VI VII VIII
Data for Major Operational
Factors
Involved
Properties
in Various Gear Scoring
of Turbopump
Gear Manufacturing
Gears
Indexes
.............
Materials
for Turbopump
Gears
Preliminary
38
Dynamic
Load Factor
XIV
Overload
Factor
and Pumped Preliminary
on Gears
._ . .
49
Case Depth to Ensure Adequate
(20-Percent
..........
Conditions
...........
Type
Compressive
61
...............
XVII
Recommended
Tip, End, and Edge Radii for Gear Teeth
...........
XVIII
Recommended
Limits on Three Types of Scoring Index
..........
XIX
Recommended
Values for Gear Surface Roughness
ix
58
59
................
Stock Removal Allowance)
57
58
.....................
Design Values for Pitting Index K
40 41
...................
Kv for Various Operating
. . .
..........
......................
Ko Related to Pump and Turbine
Fluid
Recommended Strength
39
Design Limits for Face Load and Unit Load
XIII
20
25
.................
Measurements
Sample Data Block for Gear Drawing
8
24
...............
.....................
Laboratory
7
11
.................
Accuracy of Measuring Equipment Used to Inspect Production Runs of Gears ........................
X
XVI
..........
Gear Lubricants
Tolerances
of Metrology
XV
Geared Turbopumps
Pitting Index K for Current Turbopump
Accuracy
XII
..........
of Speed Ranges for Gears
IX
XI
Geared Turbopumps
..............
63 65 76
Title
Table XX
Recommended
Rim and Web Thicknesses
Web-Lightening XXI
Recommended
Holes
Page
and Number
of
..................
Materials
........
and Material Requirements 82
for Turbopump
Gears
XXII
Recommended
Hardness Values for Carburized
XXIII
Recommended
Hardness for Material Grade 3 Gears (Carburized)
XXIV
Recommended
Processes
Turbopump
Gears
79
.........................
and Process Controls
Gears
83
............. .........
84
for Fabricating 85
...........................
x
LIQUID
ROCKET
ENGINE
TURBOPUMP
GEARS
1. INTRODUCTION
Gear drives for to medium-power
propellant pumps handling rather greater) are to be driven by a small,
(2)
a single
turbine
densities
that
engines,
a rather
unique
of
duty
cycle
turbopump
and
on
life
to 500
gears
to
reliability
High
load
• •
High speed Short life
•
Light
design, testing forth proven
1Factors
conditions
including
gear
with
hour.
combination
with
drives
greatly
or
differing
for turbopumps,
a rapid
start
testing
extends
Performance
from
imposed
have
standstill,
for
the required
life
requirements
of requirements
for turbopump
in gear
of usefulness
and
processing,
that explored the technology
for converting
0.7
or
propellants
Acceptance
one
gravity
for
flight
on a turbopump
capability
advances
materials,
The development problem areas:
approximately
(specific
in low-
speeds.
operation,
duration.
efficiency
weight
required
procedures
infallible seconds
maximum
capacity
operating levels
pump
handling
components
low weight. The up as follows:
High
acceptable
their
to achieve
dense propellants high-speed turbine;
turbopumps
different
requirement:
•
them
require
of up
•
unusual
is to drive
therefore
naturally emphasize gear can be summed
The
turbopumps are used to 4500 hp) 1 when
(1)
Rocket one
rocket engine drives (100
technology.
reliability
and
gears
quality
and
the
Turbopump
through control
severe power
refinements combined
requirements gears
were
imposed brought
in interdependent with
extensive
areas
to of
development
problem areas and evaluated potential solutions. This monograph sets developed to date, identifies the problem areas, and summarizes for successful of
gear design.
gears
for
U.S. customary
units
turbopumps
to the International
required
System
solutions
of Units
(SI units)
in
the
are given
following
in Appendix
major
A.
(1)
Tooth
(2)
fracturesimprovement
process, and Compressive
shot peening. contact failures
addendum
improved
material
Scoring
in
lubricated
effects
exciting
forces
for
purpose
this
profile,
These
problems
and
include rim
close
techniques;
tolerances-
and
turbopump
web
are
not
control
by
of gear geometry lead
'control
of
in the design the
number
thicknesses,
of
surface
texture,
or the
elements. teeth,
delivery
frequency
Design
dampers,
or
the
additional
independent,
equipment
factors
tooth
reducing
the
members.
entirely
in
of
variations
modifying
and
some
mutual
benefits
the overall success of the gear depends on minute materials, rigidly controlled in quality; closely precision
such
modification;
of lubricant
magnitude
adding
rotating
of manufacturing
and
of the gear
the
gear
of dimensions.
advances
response
of
in
and
techniques
successful
for
design
and
designer
take
attention controlled monitoring
production
of
gears.
To
obtain
the
turbopump
should
are
the
of the
increased
all
controi
modifying
changing
limits
solutions
by
rigid
modification
by improvement
rigid and
eliminated
of
modification,
gears-eliminated
accrue from each improvement; to details in all areas. Graded fabrication
and
lubricants,
-
imbalance
cleanliness,
profile
or by altering
altering
allowable
a combination
- eliminated
Cleanliness;
of better
systems. Vibrational
by
in material
proportioning,
development (4)
eliminated
dimensions,
as (3)
root
an optimum
take
gear design,
preliminary the
following
(1)
Reduce
the
(2)
Determine
(3)
Minimize
(4)
Guide
(5) (6)
Provide Ensure
pitchline the
velocity
lightest
that
the
gear
in basic
decisions
that
lowest
realistic
value.
an active
influence
the
part
in
gearing.
He
to the
weight
gear design
that
can safely
be used.
of gears.
turbopump
layout
for balancing that provisions
delivery
by aiding
steps:
the number the
it is essential
design
designer
as required. are made
for
in selecting the
the
use of the
proper
proper
gear
type
lubricant
and
and
size.
lubricant
system.
(7)
Minimize
(8)
Ensure
practical
all external and
forces
(9)
Ensure
a rigid
mount!ng
easy
reacting
on the
methods for the
of gear, gears,
and
gear
casing.
bearing, avoid
shaft, design
and
gear-case
practices
that
assembly. cause
gear
misalignment. (10)
Ensure
by
meshing After
the
individual satisified
with
or
frequencies
turbopump gear
analysis
design all fits,
that
or operating
layout and
test
has
detailing,
finishes,
and
been
gear
system
resonances
do
not
coincide
with
speed. adopted,
reviewing clamping
the all
methods
2
gear
designer
dimensions. used
on
In
must
addition,
components
supervise he that
should
the be
will affect
the gears.The designer should continue to monitor gear designand development through final production release. Operational problems should receive his prompt analysis for possibledesignchangerequirements. This monograph treats gear designand fabrication in the sequenceencountered during the design process: selection of overall arrangement,selection of gear type, preliminary sizing, lubrication system design, detail tooth design, selection of gear materials, and finally gear fabrication and testing as it affects the design.There is, of course,a good deal of cross-feed amongthe phasesof designand, accordingly, the monograph frequently cross-referencesand dovetails related material. The monograph is oriented toward the useof involute spur gears, although referencematerial for helical gearsis cited.
2. STATE OF THE ART
Satisfaction
of
following
the
severe
requirements
imposed
on
turbopump
gears
depends
on
the
the
potential
of
the
factors:
(1)
A design
(2)
Gear
that
is technically
materials
and
adequate
manufacturing
processes
that
exploit
design (3)
Quality-c0ntrol
procedures
dimensional nondestructive Favorable forms
features
long
addendum
increase
equipment specified
and
the
are
of gear surfaces
gear-tooth
roots
generous
and
of
shot-peening
can
° to
and
reduce
and
proper
monitored
by
tooth
modifications.
Tight
Special
measuring
procedures
mechanical
by specifying
the
full-depth
stresses.
plus standardized
uniform
be
27.5°),
profile
peak
to
ensure
that
properties
is ensured
representative
tensile
by tests
gear webs
often
the
frequently
with
forgings
root
specifically
are
dramatically
increases
gear
dynamometer
success
to avoid of one
of
and
test
particular
data.
lubrication
of a design seemingly supplier's
Such
has
been
unexplainable gears was
flow.
loading
peening
is an effective
tests
have
to incorporation
been by
failures. traced to
Shot
economical
prior established
design.
Gear-tooth of
life.
enables
features
successful
grain
not ground.
or back-to-back
in
for
specified
fillets
configuration amount
is necessary
with
test,
used
design
and
rapid
extensively into
process
the
in final
uniformity
For example, a sudden drop variations in a nonuniform
process. and
lubricant
delivery
gear
capacity
led to improved also is used
but
processing,
must be maintained in the fatigue life
Lubricants
are ground,
a large
after
method
close-tolerance
service
design, Even
and
that
(22.5
fillets,
and
steels
manufacturing
back-to-back
accumulation evaluating
root
accuracy
adequate
conformance
processes
angle
of operation
with
from
in simulated The
A typical
pressure
vacuum-melted
machined
contacting
design.
large
consistent
analyses.
Specification
aid.
fabrication
pinions,
of materials
metallurgical
Testing
and
smoothness
mill-lot-controlled,
Gears
include
ensure
with increased sensitivity and tolerances actually are obtained.
Procurement using
tolerances, tests.
design
with
tolerances
that
load
to monitor sequence
lubricant
of actions
systems with quality
in the
have
been
conventional and
design
the and
subject
of development
unconventional
testing
lubricants.
that
Testing
effectiveness. and
manufacture
of aerospace
gears
is as follows:
After engineperformance considerationslead to the selection of a geareddrive transmission, the generalfeatures of the gearsystemare determined: basicgeartype, the sizeand number of gears, and the speedsand rotational directions of the shafts. The gear design then progressesthrough preliminary determination of operating stressesto detail selection of pitch, number of teeth, profiles, required modifications, material selection, and creation of manufacturing drawings and specifications of materials and processes.Acceptancetests and performancetestsusedasdesignaidsconcludethe geardevelopment.
2.1
GEAR
Trial
layouts
attempt
of
the
the
desired
speed
compact
ratio
•
Gear-tooth
load
•
Gear
capacity
• •
Practical Minimum
distance speed
and
design
therefore
of the
Particular
care
rotational
gears
dictated
features
of and
appear
Nomenclature
delivery
system.
materials;
during pumps,
I. Table
stresses.
used
Manufacturers
1Symbols;
factor effort
in figure
within
ducts
provides thereof
adequate then
constraints
guide
the
spacing
are selected
imposed
to
by
design
to avoid
undercutting.
in achieving
success
is expended
to ensure
turbines, and
and
is noted
the views
tables
figures
that
of
the
arrangement
for
existing
detail
design
gear
high-speed
of lubricants
Direction
of
on assembly
systems gear
selection
the gear
specifically
major
Schematic
in the
accessories.
gear
II lists
in high-power
trains
and
obtains rotation
gear in
proper often
is
drawings. major values
used
turbopumps of power,
are speed,
in major
turbopump
is based
on American
1.
in the
Association
specifications;
that
diameters
and
available
main-power-transmission
lubrication,
the
direction
gear size of pinion teeth
requirements
in table
turbines,
arrangement and
rotation
considerable
of
summarized systems
and
is a major
is exercised
by engine
physical
pumps,
capacity
lubricant
direction
including
of gears
and volume
maximum number
of the
system
number
Center
systems,
B.
most The
•
Lubrication
Gear
turbopump
components.
achieve
The
the
to achieve
of these
the
SYSTEM
vehicles,
and
and
(AGMA)
standards
pumps,
and engines;
throughout (ref.
the
1) except
and abbreviations
used
text
where
noted.1
herein
are identified
in Appendix
Table
Speed
t. -
Gear
System
Data
for
Major
Lubrication
reduction ratio
Input speed,
(system)
rpm
Input/pump-shaft
Power
Oxidizer
Fuel
hp
Atlas
4.885
4.885
4920
Gearcase
supply
internal
gpm
pressure, psig
pressure,
RP-1 and
psig
Gear
material
Gearbox
weight, Ibm
6265
150
5.5
620
4.0
AMS
1.2
625
1.4
A_MS 6265
Specified
Attained
3750
>
6500t3
6000
>
20 000
extremepressure additive
3) sustainer
(Mark
Life,
Lubricant
Lubricant
boosters (Mark
Turbopumps
system
flow,
transmitted,
32 730
Atlas, Thor, Saturn 1B
Geared
sec
Lubricant
Vehicle
Operational
38 085
3.750
3.750
a
MIL-L-
1650
approx.
4)
40
(gearbox unitized)
6086 or MIL-L-
not
25336
Titan
23 000
II, 1st
2.87
2.62
MIL-L-
4466
stage (LR-87-AJ-5) Titan
3.4
15.0
30
AISI 4620
II, 2nd
22 800
2.82
NA
924
MIL-L-
stage
or
228
2500
> 6000
114
2500
>
9310
7808
1.5
30
15.0
0.4
40
3.5
AISI 4620
6 0130
7808
(LR-91 -A J-5) Centaur
30 000
2.50
1.00
80
Dry film b
(RL10)
9310
24 800
1.721
0.977
357
(LR81-BA-11)
a 98%
RP-1
b 25%
powder,
= not
plus
available.
2% 75%
Oronite AMS
262 3132
(zinc
dialkyl
varnish,
AMS
MIL-L-
1500
7808
dosed
cm 3,
Not plied
sup-
system
pressure
under
Does not
thinner
as required.
The
powder
consists
of
10
parts
MoS
2 and
1 part
graphite
by
case is part of
weight.
420
20 000
case
AMS 6250 NA
apply
dithiophosphate). 3170
Gear engine
and hydrogen
Agena
NA
AISI
NA
NA
Table
II. -
Gear
Design
Data
for
Major
Operational
Geared
Turbopumps
Sur_ce
Vddcle (system) Atlas, Thor, Saturn IB boosters (Mark Atlas (Mark
oo
3) sustainer 4)
Titan II, 1st stage (LR-87-AJ-5)
Gear (fig. 1)
II, 2nd
stage
(LR-87-AJ-5)
Centaur
(RL10)
Pitch
velocity, _/min
diameter, in.
Diametral pitch, in.- 1
Number of
Power, hp
Speed, rpm
A
4 920
32 730
9 474
25 727
3.00
11
33
B C
4 846 4 846
15 430 15 430
19 793 19 793
25 727 16 676
6.36
11
4.125
D
4 777
6 700
44935
16 676
A
1 650
38 085
2 730
B
1 650
10 157
I0 230
A
4 466
23 000
B
2 320
11 000
C
2 146
Tooth
face
compressive
Pressure Unitload,
stress,
width, in.
angle, deg
1.44 1.32
25
48 247
263
067
70
25
52 633
263
067
8
33
1.46
52 584
263
067
9.50
8
76
1.64
25 25
46 146
263
067
20 000
2.00
12
24
1.12
25
29 200
20 000
7.50
12
90
1.00
25
32 800
12 200
16 600
2.75
11.25
31
2.125
185
000
16 600
5.78
11.25
65
1.99
20 20
26 100
13 300
25 600
191
000
8 010
16 900
16 600
16 600
16 600
89 81
20
8 800
11.25 11.25
2.00
2 320
7.91 7.20
2.125
20
25 500 26 108
175 000 142 000
A
924
22 800
2 550
16 400
2.75
12
33
1.00
173000
924 924
10 900 8 100
5 340 7 190
16 400 16 400
5.75
12
69
0.875
20 20
22 300
B C
25 500
184 000
7.75
12
93
1.00
20
22 300
129 000
D Titan
Torque, m.dbf
Pitchline
I
teeth
psi
psi
A
80
30 000
167
15 720
2.01
13.96
28
1.20
22.5
2 140
56400
B C
80 80
12 200 12 200
414 420
15 720 15 720
4.94
13.96
22.5 22.5
56 400
13.96
1.10 0.70
3 340
5.01
69 70
3 350
53 600
20
16 200
121000
20 20
12 700
120 000
16 200
126000
Agena
A
357
24 800
907
17 400
2.6875
16
(LR81-Bg-11)
B C
157 200
25 300 14 410
390 874
17 400 17 400
2.625
16
43 42
0.500 0.375
4,625
16
74
0.375
0
T
Atlas, Saturn
F
Atlas
Thor, and IB boosters
Titan
sustainer
II,
B
T
0 A Titan II, sta_e and Centaur
A,
B,
Figure
C,
Agena
2
D:
gear II)
identity
O:
oxidizer
F:
fue i pump
T:
turbine
(used
in
table
pump
1. - Schematics of gear arrangements turbopumps.
9
in major
operational
stage
1
2.1.1 Gear
Speed Ratio
trains
optimum
in rocket turbine
main-power-train lubrication through The
following (1)
speed
ratios
for
hydraulic
limitations must
usually
is
common
be
gear
and
electric
on speed number
and
is
in a mating
Multiple
reductions
strength
and
are
a
are
normally
speeds.
turbopumps.
generators
Accessories
driven
high
Table
at the
I lists such
desired
as
speed
ratio: of
teeth
obtained
required
on
by
each
gear;
choosing
to obtain
tooth
single
driven
matching
pump
hunting-tooth
numbers
of
action
teeth
with
no
set of gears.
nonoptimum
in
permit
optimum
trains.
a whole
desirable
drives
lower
major
pumps, gear
much
are imposed
factors
attempted
main-power
normally
accessory-drive
There
(2)
turbopump
with
pumps, smaller
engine
speeds
mesh.
action
In
large will
general,
overall
result
ratios.
if
too
a maximum
Losses
large
ratio
in tooth
a reduction
of
is
5 per
mesh
is
the
minimum
permitted. (3)
The
number
number
Although
the
flexibility
in engine or
fixed
for
Gears
to avoid
speed
of
performance
a gear
most
are
the
be
maintained
teeth.
above
Minimums
for varying
gear
sizes
5).
if a change
For
balance
must
weakening
2 (ch.
ratio
pinion
train
in relative
rocket
made
often
engines
by trimming
is an asset, output that
pump
the
is required use
fixed
impellers
fixed
ratio
limits
for a performance mixture
or by
ratios,
changing
fine pump
Speed Capability
have
at higher ranges
been
designed
speeds with
velocities R&D
in the
in reference
throttling.
adjustments in flow discharge orifices.
2.1.2
teeth
required
are given
change
of
tests
and
is so difficult
corresponding
up
to 25 727
indicate
that
operated
at pitchline
velocities
as to be impractical. risks,
ft/min
have
these
gears
requirements, been
utilized
can operate
10
Table and
up to 50 000 III
lists
potential
in operational satisfactorily
broadly
ft/min;
classified
problem
areas.
turbopump
gears
at speeds
operation speed Pitchline (table
up to 27 200
II);
ft/min.
Table
III.-
Pitchline velocity, ft/min 4 000 to 15 000
Characteristics
of Speed
for Gears*
General classification Characteristics
of speed range Normal
is required.
First reductions of turbine-driven pumps are in this range. Centrifugal stresses can cause problems. Gear tooth accuracy is critical. Dynamic balance is important. Rela-
High
tively few manufacturers 25 000 to 30 000
and hazards
These speeds are representative of those attained with most high-speed gears. Centrifugal stresses cause no problems. Many manufacturers are capable of building the units. Dynamic balancing is not critical. Moderate gear tooth accuracy
15 000 to 25 000
Ranges
Very high
are qualified
and experienced.
These speeds generally are found only in rocket engine and aircraft gas turbine test rigs or in large industrial gas turbine drives. Centrifugal stress problems are critical. Failures are potentially dangerous to human life because of probable casing rupture. Solid rotor designs usually are required for the gear. Gear tooth accuracy is critical. Lubrication is critical because of windage problems and possible excessive temperature rise on working tooth surfaces. Rotors must be balanced to fine limits. Few gear manufacturers are qualified
30 000 to 45 000
Ultra high
to fabricate
gears for this speed range.
This is the "frontier" area of extremely-high-speed gears. Failures are highly dangerous. Even the best solid rotor designs may rupture because of small metallurgical defects. High-speed balancing techniques are required. The best gear manufacturers in the United States have had some successes and some real problems in the few special aerospace gears that have been fabricated. No turbopump plications in this speed range are in use.
*Adapted
from
a report
presented
by D. W. Dudley
at ASME
11
Annual
Meeting,
1966.
ap-
2.1.3
Gear Type
Turbopump types.
main-power
For
of the
most
center
distance. efficiency
tooth
action
designed of
rather
3 gear
loads
new
(table
and
The
choice
between
higher
used
used
and
II)
will make
and
spur
as pitchline
10
\
velocity
increases.
types
in power can
be
10
2O
Pitchline
velocity,
2. -
tests
gears and
power
have
been
for accessory
increments spur
shown
despite
gears for the
the
cost
of a
2 presents
gearing.
velocity.
more
bevel, because
used
for
drive
gears
drive
the relative
helical usage
of
Single
helical
Double
helical
ft/min
Smoothness
as
trains
on speed,
50 x 103
usage of gear types
transferred
is based
Spur
40
pitchline
such
Bevel
Figure
Relative
Non-coplanar
gearing
in table originally
existing
attractive
I
30
in a non-turbopump of 6 when helical
main
shown were
,J I
overlap. For example, was reduced by a factor
turbopulnp
smoother
gears
the level
in
of their
levels
in moderate
improve
--0--
2
loads
place
normally
- .orl 1
Figure
two
and
beyond
gears
I
4
0
the
capacity
speed
one
variations
load
i
6
of small
because
and
uprating
of other ranges,
trains
and
took
exclusive
power
turbopump
to adapt
configurations
0
gearing;
power most
of helical
; \/o r-4 ID ¢lX
high
tooth
f
8
ID
temperature
higher
as uprating
the use
J
ID tan
their
Further
gears
is its tolerance
Hqwever, desirable
spur wide
of manufacture.
helical more
present
designs.
and
to turbopump
with
speeds;
more
helical
cost
gears
if the
loads
gearing
applied
requirements.
involute
high
of involute initially
economically
train
design
being
been
coplanar
involves
helical
design
modest
to initiate
new
gears
have
more
were
simplicity;
initial
it was
than
Mark
the
which
features
gears
and
for
power,
Spur might
been
incorporate
gearing,
advantageous
high II had
trains
turbopump
as a function
of operation gradually
to
of
is a definite successive
teeth
advantage
of helical
because
of
power-gear application, vibrational gears were substituted for spur gears. worm,
and
of their
lower
connections
in turbopump
12
hypoid
gears
efficiency
to power systems.
trains
have
(increased
not heat
tooth
amplitude
been
used
generation).
for hand-rotation
torque
in
2.1.4
Gear Mounting
Figure
3 presents
three
methods
for mounting
gears.
-_0.7D
to
1.0D
_Gear
and
bearing
I
(° I' ii
D
-I S
(a)
=
0.6D
Straddle
mount
(b)
Overhung
(c)
mount
Mount
for
with
single
idler
gear
bearing
Figure 3. - Gear mounting methods.
Straddle
mounting
under are
load
that
general
(fig. cause
rigidity
individual
application.
Overhung
mounting is the
mounting, mounting
the
and
are
turbine
actual
3(b)) shaft
shown
in the
figure,
Mounting
of idler
the
gears.
This
configuration
teeth
line
up
Rkl0 gear
capacity, of the
since bearing
detailed
misalignment.
are
the
result
calculations
when
4 (Atlas
General
but actual
in order
and
is used
Mark
is sought.
under
idler
dimensions
sometimes
deflections
possible
distances
after
of the
rigidity
whenever
in center
selected
(fig.
maximum are
is used
changes
guidelines;
mounting
example
3(a))
sustainer)
dimensions
The of
and
saving
to
maximize for the
is a major
turbopump. from
shown
deflection
goal.
As with
for proportions result
deflections
proportions
attempts
of stress
space
guidelines
to minimize
An
straddle
of an overhung
detailed
analyses
of the
load. gears
the
on
with
tangential
is shortened
a single
ball
bearing
tolerates the
driving
forces
on
by rotation
3(c))
misalignment gear
the
(fig. teeth.
idler
of the outer
13
gear
has been
used
by rocking A potential
teeth
race.
advantageously
the
ball
problem
are additive.
bearing area
In addition,
on so the
is bearing the
life
ii
Cryogenic mounting
volute pins Mainshaft
Liquid
gear
oxygen
\
pump
Fuel
pump
Intermediate and with 4_
Accessory
gear
High-speed with
("A")
integral
pinion
bearing
races
Quill
Figure
4. - Schematic Saturn
of
Mark
IB boosters).
3 turbopump
shaft
(Atlas,
Thor,
and
accessory integral
("B-C" drive bearing
gear pinion) races
2.1.5
Gear Attachment
Secure will
attachment
create
additional
mounting to
make
gears
in the
cluster
gears.
If
gear
the
Mark
must
shaft
is necessary
deflections.
surfaces.
been
the
of the
Relative
In extremely
highly
gear
with
integral
3 turbopump
be
for gears
removable
motion loaded
its trains,
from
the
the
shaft,
-
used.
Radial
through between fretting increasing
position
the
spline.
stacked of
the the
The
faces
of the
clamping-nut
_
for
mounting
by
clamping-nut
components
_
Method
is maintained due Mark
example,
"A"
pinion
the
mounting
solution
figure and
and
the
method
looseness
damage
to the
to fretting
4 shows "B-C"
any
the
has
one-piece
accessory-pinion
shown
in figure
5 is
the
spline
is made
thrust
4 (Atlas
a detachable
tight-fitting
torque to
in fretting
a satisfactory
For
because
Loose fit
pilots
5. -
loads,
_.+__._
Tight fit
Figure
high
will result
gears,
shaft.
gear
under
loads, sustainer)
torque.
15
gear.
pilots; high
driving
enough
bending, turbopump
or
torque
to prevent thermal pinion
is transmitted relative
motion
expansion. was
eliminated
Severe by
2.1.6
Backlash
Backlash
is the
clearance
between
contact
on
stackup, indicate
differential thermal growth, and the need for a change in backlash.
interference,
Gear
nondriving
high
side
forces,
and
of
heat
of a given
backlash the
(ref.
gear
and
under
lubricant Absence
any
to lockup
tooth
thickness
in the
design
combination
of
film buildup. of backlash
leading
the
1) is provided
tooth
generation
gear
of
to avoid tolerance
Test experience will lead to actual
and
gear
may gear
failure.
Load Capacity
tooth
mechanical
maximum tooth the
sufficient
width
gear. the
but
space
meshing
2.1.7
Minimum
the
capacity
details
(sec. 2.2),
required
been
gear
uprated;
considered
in the used
designed
for
10 years
to handle
increase
required
fabrication experimental Tooth
nearly
improvements changes
recognizes
that
uprating
train
Thor,
in were
and
II). The
materials, then
Further,
development IB
over
a period
detail
is the
are
Mark
3
Originally
of approximately nature
design,
into
has
changes
boosters.
incremental
gear
turbopump
design
Saturn
consolidated
achieving (sec. 2.1.9),
in determining
every
future
of evolutionary
(table
However, alignment
nearly
through
was developed
horsepower
capacity.
(sec. 2.1.8), (sec.2.4).
Atlas,
gear
load
fabrication
example the
the
these
and
designer
An
of gear
lubrication
for
for
5000
small
of the
power
lubrication,
design
and
requirements
after
verification.
mechanical
strength,
and
compressive
strength
the on
is composed
the'tooth's stress
reliability, depends
design. engines
horsepower,
techniques;
the
provisions
the
basis
(sec.2.3),
capacity,
original
1800
the
optimizing
materials
load
in
forms
requires
therefore,
gear
train
strength also
gear
the
resistance
levels
depend
material
material,
of
root
bending
to
chipping
of the
on the
required
life
quality its heat
level,
and
treatment,
strength, edges.
compressive
The
(number
allowable
of stress
manufacturing
tolerances.
and
of stress
avoidance
contact
bending
cycles),
the
Chipping
and
desired
resistance
concentrations
at the
edges.
2.1.7.1
TOOTH
Since
a gear
larger
tooth,
ROOT
tooth
BENDING
is similar
designated
relationship
is reflected
gear tooth defined as
strength
by in the
used
STRENGTH
to a cantilever a gear
beam,
numerically tooth
in preliminary
physical
smaller breakage design
16
size
diametral
index,
"unit
calculations.
is an index pitch, load,"
Unit
of strength;
is stronger. which
load
for
a This
is a gauge spur
gears
of is
Wt Pd U L
-
F
where UL = tooth
breakage
total
tangential
W t =
F = effective
face
index,
or unit
tooth
load,
width,
load,
psi
lbf
in. number
Pd = diametral
pitch
of gear tooth
pitch Turbopulnp The
gears
resulting
short
use
required
materials gears
and
classes
in table quality
Refinement
of unit the
The
AGMA
cantilevered [spur Values
for
large-scale factors factors
are
(K,,,), from
Tests
used
and
of
account
Digital
have
the
and
In lieu
reference
of root
by the
imposed
turbopump
material
on
power
quality gears
of 12 500.
are listed
gears.
grade made
of
Reference
as AGMA
3
quality
stresses
geometry
is obtained and
by
by
derating
alignment.
the
gear most
methods
the
basis
and
geometry
dynamic the
values,
and
to be the
by
provides
bending
tooth
to
accurate
be
a shaped
available
(refs.
5
8.
A
gears]).
calculated
are
possible
control
Accessory
load
tooth
assume
bevel
possible,
unit
for
3
(Y factor)
sometimes
of 25 000.
of service,
tooth
of empirical
programs
estimate
severity
size (Ks),
of AGMA
tolerances
this approach
When
is made
for existing
load
for aircraft
and 4.
form
for
(Kt).
saving
loads
made
compensating
7 [spiral are
gear tooth
to account
colnputer
shown
stress
for
temperature
experience.
in
gears],
bending
layout that
outlined
6 [helical root
quality,
used
quality
to a maximum
9-19)
those
stringent
Unit
Dimensional
accurate
factors
than
weight
gears
to a unit
through
by
on the gear
plate.
gears],
gears.
grades.
to a more
higher
more
similar
1 are limited
9-16
load
methods
and
limited
in.
consequent
features,
quality
load
unit
dependent
are
grade
2 (pp.
lnultiplying
the
loads
for turbopump
material
in references
and
II. Geometrically
generally
aircraft
factors
gears
diameter,
for unit
design
manufacturing
material
discusses
designed
special
quality)
AGMA
are
of smaller
life,
are listed
2 (aircraft
often
of teeth
=
for
loads values
suggested
utilized
presented selecting
in the
(J factor).
(Kv),
overloads
for the
modifying
values
given
to determine
reference
stress-modifying
Further (Ko),
misalignment
factors
in reference
form
and
modifying are derived 8 are used.
geometry
factors
for gears. Allowable by
test
processes allow
values for
for gear-tooth-root
carburized
(e.g.,
shot
use of higher
and
nitrided
peening), stress
and
bending steels
stress (refs.
tolerances
for given 3 and
developed
levels.
17
9). and
cycle The
life have
been
special-quality
refined
for
established materials,
turbopump
gears
Figure
6 presents
tile allowable
bending
stress
as a function
of the
cycle
life fox" carburized
150 x 103. c/l
100 laO r_ .r-I
--
80
g -O
60
g %
50
,,
o
,,,,,I
10 3
I
I0 _
105
I
I
106
107
I 108
109
Cycles
Figure
6. -
Allowable gears
steels
used
quality
in aerospace
grades
gears
1 and
2 are
taken
from
3 represents
the
stress
levels
grade
4 represents
the
levels
attainable
and
technology.
gear
altered
quality.
to obtain
2.1.7.2
TOOTH
Gear
tooth
that
is used
Figure
Note a linear
FACE
capacity
that
with on
COMPRESSIVE
3 and
the
the
finest
probability
the
life
grades.
for
The
represent
for turbopump
the relationship
to withstand
in preliminary
scale
vs cycle grades.
quality
reference
attained
stress quality
material
7 relates the
plot;
bending material
of various
grade
lubrication
root
of four
gears available of tooth
abscissa
is not
presented
stress
aircraft under
values practice.
present
design,
Material
practice,
and
manufacturing,
breakage
truly
for AGMA
logarithmic
and
to bending
stress
but
been
has
is nonlinear.
STRENGTH
compressive
stress
is reflected
in the
tooth
pitting
index
designs:
-K = Wt(me+l) Fd \ mG
(external
-K = WtlnG Fd mG-- l )
(internal
18
gears)
gears)
(2a)
(2b)
K
ii0
I
xlo3 i00
_
I
I
_ 1_'4't/
_e_s
_"
_i
9O
J c'l ©
80 C -M
,o
7O
_o
6o
I
5o
I
0.i
o.oi
Probability
Figure
7. -
of tooth
Probability stress
of
for
Wt = total
pitting tangential
F = effective d = pitch m(;
index,
face
diameter
= gear ratio
=
tooth
gears
of
width,
dimensionless load,
number number
lbf
in.
of pinion,
in.
of gear of pinion
5 breakage,
tooth
where K = tooth
I
i
teeth teeth
19
breakage four
material
I i0
20 x 106
cycles
vs
root quality
bending grades.
Table
IV
presents
the
Table
Type
K values
IV.
-- Tooth
used
in current
Pitting
Index
turbopump
K for
PLV,
of gear
gears.
Current
Turbopump
mG
power
For
preliminary
for
25 ° PA
applying and by
derating
quality the
Figure
design, gears,
(refs.
methods 8
presents
2.1
2.75
21 000
3.75
2.00
1 800
27 000
2.1
3.00
2 050
13 000
2.3
4.12
2 500
1 tO5
1 to6
to 7 000
0 to 100
Actuator
the
and
as
tooth 7100 depending
10
1 1).
given
in reference the
allowable
contact
For
on
compressive
final
20 ° PA load
values
to 1 000 2 000
stress
gears;
may
a closer
application,
design,
500
2.5
oo (rack
K '/2 for
factors and
1 200
18 000
2 000
Accessory
K
67
in.
ft/min
Main
Gears
be estimated
misalignment, for
as 6500
determination
compressive
K V_
is made
surface stress
conditions are
calculated
1 1. compressive
stress
level
as
a
function
of
cycle
life
.el
bOO x 103 %
3oo --
gl
200 --
I
I
I
I
I
|
-4
E O O
,13
o_ 100 l03
by
I
I
I
I
I
i0_
105
106
107
108
Cycles Figure 8. -- Allowable
compressive
gears of four
2O
material
stress vs cycle life for quality
grades.
10 9
for
carburized steels used in aerospace therein for AGMA quality grades
gears 1 and
of various material quality 2 are taken from reference
grades. 3 and
The stress values represent aircraft
practice; the stress values shown for the material quality grade 3 in figure 8 are allowable compressive stresses for turbopump gears designed and fabricated with present practices; the curve labeled grade 4 represents the stress levels attainable with maximum use of presently available technology in design, manufacturing, and lubrication. Figure 9 presents the probability of tooth pitting as a function of compressive stress (as before, the scale has been modified to obtain a linear plot).
350
x 103
I
I
I
I_
325300
°
1
250
225_ 200 0.01
0.I
i
Probability
Figure
9. -
Probability stress
2.1.7.3
CHIPPING
potential
nitrided process.
for
case; the Chipping
of tooth
of
tooth
I0
pitting,
pitting
gears of four
20 x 106
cycles
vs compressive
material
quality
grades.
RESISTANCE
Chipping of tooth edges may loss of load capacity because gear system. The
for
5
chipping condition tendencies
result in progressive degradation of reduced load-carrying surface
exists
in nitrided
is aggravated are reduced
gears
by by
21
the
because corner
of the gears as a result and (2) contamination
of the extreme buildup
that
occurs
brittleness in the
of (1) of the
of the nitriding
• • •
Limiting case depth in thin sections Establishing a minimum tooth tip width Providing adequate radii and blends at corners
Tip, end, and edge radii on the gear tooth of active surface resulting from unacceptably insufficient radii. Because these radii often prevent wide variation. On critical gears, radii
Chamfers are avoided are established before
as a final
finishing
2.1..8
Lubrication
of tooth
tips,
ends,
and
are controlled carefully to prevent large radii or stress concentrations are hand ground, careful control
edges.
excessive loss arising from is exercised to
because they can lead to stress concentrations. carburizing and are refined after heat treatment
step.
and Cooling
Gear lubricants perform a complex function of reducing friction, preventing destructive scoring at the sliding contact, and removing the heat generated by the tooth action. In order to minimize the weight charged against the lubrication system, the designs for large turbopump lubricant
at
gear the
trains incorporate minimum quantity
material
capabilities.
2.1.8.1
HEAT
The lubrication tooth friction
sophisticated required
flow systems that meter the most to maintain gear system temperatures
effective within
REMOVAL system must remove the heat generated losses, (2) windage and oil churning, and
in the transmission (3) bearing losses.
as a result of (1) The total of these
losses for spur gear trains is roughly 0.5 to 0.7 percent of the power transmitted per mesh. The largest loss occurs as a result of tooth friction except in very-high-speed gear trains where oil churning may absorb substantial power. Losses for rolling-contact bearings are generally much less than the associated gear losses. Methods for calculating gear loss based on theoretical considerations or on empirical results are given in reference 2 (ch. 14) and in reference
12.
Low gear
losses
• • • • •
can be achieved
by any
or all of the
following
actions:
Lowering the lubricant viscosity Carefully designing internal contours of the gear case to prevent Using helical gears; a theoretical advantage is cited in reference
oil trapping 2 (ch. 14, p. 6).
(Gear designers are not unanimous on this point, however.) Ensuring that more tooth load transfer occurs during the arc of recess the arc of approach (ref. 2, ch. 5, p. 18) Reducing the gearcase internal pressure to reduce windage.
22
than
during
2.1.8.2
SCORING
The
scoring
any
known (1)
resistance single Gear •
(2)
of a gear design
value.
The
design Contact
following
is affected factors
by many
are known
factors
and
is not
to affect
gear
scoring:
by
Sliding velocity Material
• •
Surface roughness Accuracy of tooth
surfaces
Lubricant properties • Flash temperature • Viscosity
(3)
Chemical surfaces)
Lubricant
activity
(extreme-pressure
compounds
react
chemically
with
tooth
scoring
resistance
based
on
variables
• •
Temperature Flowrate
• •
Method of application Cleanliness
V summarizes
the
various
scoring
indexes
that
predict
limited number of variables; also listed in the table are factors that probably resistance but have not been incorporated into any scoring index formula. indexes in descending order of apparent accuracy are (1)Bodensieck specific (ref. 13), (2) AGMA utilized only as a rough Reference
2.1.8.3
represented
stress
• •
•
Table
PREVENTION
16 presents
flash temperature estimate of scoring an evaluation
LUBRICANT
(ref. 14), and (3) PVT risk and is not considered
of various
scoring
a
affect scoring The scoring film thickness
(ref. 10, p. 53). PVT is a valid basis for design.
indexes.
PROPERTIES
Heavily loaded turbopump gear trains have been lubricated with petroleum-base oils, synthetic-base oils, and fuel-with-additive mixtures. Gaseous hydrogen has been used as a coolant in conjunction with dry-film lubricants applied to the gear teeth, and with a mist additive. Various propellants have been tested for load-carrying ability, but are not used as lubricants A summary
in operational of the
turbomachinery.
properties
of turbopump
gear
minimum operating temperature requirement search for low-temperature oil-type lubricants.
lubricants
is given
possesses insufficient scoring resistance for the Thor and Atlas gear was developed to fulfill both the Thor and Atlas high-tooth-load requirements; this lubricant tends to deteriorate in storage and must for scoring
1Appendix
resistance.
B presents
complete
titles
for material
specifications.
23
in table
of some vehicles (Thor, MIL-L-7808 oil I , used
VI. The
Atlas, Titan) in the Titan
-30 c F led to a engines,
trains. MIL-L-25336 oil and low-temperature be checked periodically
Table
V. -
Factors
Involved
in Various
Gear Scoring
Indexes
Scoring index Specific film thickness Scoring
factors a
(ref. 13)
Flash temp. (ref. 13)
PVT b (ref. 10)
Contact PV b
time
(ref. l 5)
X X
X
X
X
X
X
X
X X X
X
X X
X X
X X X
Surface roughness Gear accuracy
X X X
X X X
Initial temperature Material constant
X X
X X
Tooth load sharing Profile modification
X X
X X
Oil viscosity
X
Constant
load
Instantaneous Unit load
load
Rolling velocity Sliding velocity Entraining velocity Slide/roll ratio (specific Radii of curvature
X X
sliding)
of tooth
X
Conductivity
Tooth surface Waviness
X
topography
Lay Surface hardness Extreme-pressure property Density of lubricant
of lubricant
Specific heat of lubricant Coefficient of friction
X
X
Overloads (nature of application) Lubricant jet velocity aFactors marked with X enter into the calculation of the listed scoring index. bp ,, Hertz contact pressure, psi; V = sliding velocity, ft/sec; T = distance from pitch point to tip of tooth, in.
24
X
X
Table
VI.
-
Properties
of Turbopump
Gear
Lubricants
Lubricant
Property Viscosity, centistokes 210 ° F
Pour
°F
point,
value
Typical
MIDL-7808 Diester base Required
value
4
25 to 34 -
-40 ° F °F
base
-
100 ° F
Flash point,
I
Petroleum Required
Fuel-additive
MIL-L-25336
MIL-L-6086
Required
value
value
base
Hydrocarbon Typical
400
5
3 min.
4
11 min.
12
Pass
value
Typical
value
2 11
400 min.
450
-75
Pass
max.
a
compound
1500
430
-75
Pass
Required
value
17 1300
Pass
40
Typical
3 min. 11 rain.
30 30 500
280
value
Diester
mixture
110 -36
130 Pass
(freozing
point)
Load-carrying
capacity,
Ryder
gear test:
Load,
ppi
3 450 b
None
Test material --X MIL-L-6081
1700 rain.
140 to I60 b
100
76(2
1900 to 3100 b
76 to t30 b
tests)
to 5000 b
116 (2 tests)
l16to
100 b
Not defined
4000
to 6300 c
140 to 200 b
109 (6 tests) 107 (8 tests)
68 (8 tests) 50 d
40
2500
111 (4 tests)
72 (4 tests) 70(6 tests)
Load-carrying capacity, Shell four-ball tests
min.
2800
22 to 25 d
40 d
29 to 33 d
80 e
aILP-1 with 2 to 3 percent of Oronite 262 additive. bRocketdyne data; test: Federal Standard Test Method 791, method 6508.1 (see Appendix B for complete designation of this and other referenced test methodsl. CShell Research Colporation data. dRocketdyne data; test: Federal Standard Test Method 791, method 6503.2. epran & Whitney data; test: ASTM D-2596.
Maximum scoring resistance has been obtained with a mixture of RP-1 and Oronite 262, a zinc dialkyldithiophosphate additive (ref. 17). Turbopump proof-test runs are conducted with 10 percent by volume of the additive; in subsequent operation, the lubricant is RP-1 fuel mixed with 3-percent additive. The 10-percent-additive concentration used to "run in" the gears gives added scoring resistance in subsequent operation, apparently because of a residual extreme-pressure film. A heater blanket is used to maintain a relatively constant viscosity of the additive over the ambient temperature range expected and thus prevents excessive variations in additive concentration. The
RL10
turbopump
gears
successfully at approximately 15 800 ft/min PLV. Except
(AMS
6260)
250 ppi for the gear
are
cooled
by
hydrogen.
(pounds per inch of bore, which is chrome
These
gears
face width) face plated, a dry-film
operate
loading lubricant
at 1
is applied to the entire gear for lubrication of the active tooth contacting surfaces and for corrosion protection of the rest of the gear. The hydrogen is injected into the gear case as a liquid but probably performs its cooling function during vaporization and as a gas. Some rig testing has been conducted in which gears untreated with solid lubricants were run while submerged in various propellants (refs. 17 and 18). These tests showed that rocket engine propellants, although they may be good coolants, are poor gear lubricants and that the materials compatible with propellants are unsatisfactory for gears. High wear rates and extensive scoring occurred at face loads of 500 to 1000 ppi at a PLV of 10 000 ft/min with the fuels RP-1, liquid hydrogen, ethylene diamine, UDMH (unsymmetrical 1The
dry-film
AMS
3170
powder.
lubricant thinner
The
coating
consists as
of
required. thickness
The is
1 part
by
powder
specified
weight
of
consists to
be
0.5
of to
a powder 10
2.0
parts mils.
25
mixed by
weight
with of
3 parts molybdenum
by
weight disulfide
of
AMS and
3132 1 part
varnish of
with graphite
dimethylhydrazine), (inhibited has been
2.1.8.4
and
N 2 H 4 ; oxidizers
red fuming nitric acid), confined to low load and
LUBRICANT
DELIVERY
giving
similar
and N2 04 (ref. speed levels.
results
18).
were
As a result,
liquid
oxygen,
cooling
with
IRFNA propellant
SYSTEM
The Titan engine turbopumps use a recirculating oil system with a feed pump, scavenger pump, and heat exchanger. The single-pass systems used in lubrication systems for Thor, Atlas, and Saturn S-IB engines are operated by gas pressurization of the lubricant tank (Thor), positive displacement pump pressure (S-IB). In the
Titan,
disengaging side of the Further
Thor,
Atlas,
pumps
and
side of the mesh. mesh. The technical
discussion
Lubricant
of lubricant
delivery
(Atlas),
or a fuel-additive
S-IB systems,
the
blender
lubricant
spray
unit
streams
activated
are directed
Some designers prefer lubricant impingement rationale for the choice is summarized in the delivery
may
be found
in references
2 (ch.
Advantages
by fuel
to the
on the engaging table below.
15),
19, and
20.
Disadvantages
point Engaging side
Provides maxinmm elastohydrodynamic eration.
Disengaging side (preferred for high-speed gears)
potential for fihn gen-
Allows use of lower lubricant
Requires
pressure
flow.
Provides cooling at the point where gear tooth surface is hottest; heat is removed before it is conducted into gear mass.
Requires lubricant
Reduces tile possibility gear coolant trapping.
Some
gearbox
bearing
Trapping of oil between tips of teeth and roots of meshing teeth may result in surface erosion of teeth.
failures
have
been
tight control
of lubricant
careful targeting velocities.
and high
Most lubricant may be thrown before next mesh occurs.
off
of
associated
with
a change
in lubricant
circulation
caused by a progressive drop in gearbox internal pressure during flight. A concurrent increase in foaming of the lubricant also detracted from the cooling effectiveness of the lubricant. Remedial practice has been to (1) redesign the bearings, (2) use lubricants with low foaming tendencies, increasing windage.
or (3)
pressurize
the
26
gear
case
to improve
lubricant
circulation
by
2.1.9
Gear Case
To achieve rigidity and light weight, gear magnesium) castings with integral mounting loads arise from several sources: (1) (2)
Gear tangential External loads radial loads)
(3) (4) (5)
Loads arising from Internal pressure Thermally induced
Cryogenic pump flow and prevent heaters sometimes
driving reacted
and separating through the
the use of the loads
cases are made of light metal (aluminum or pads and .stiffening rings and ribs. The gear-case
(e.g.,
loads gear case
gear
from
(e.g.,
case as the
cryogenic
pump
and
turbopump
pumps
and
turbine
thrust
and
mounting hot
turbines)
volutes often are pin mounted to the gear ca_e (fig. 4) to minimize heat uneven chilling of the gear case and consequent misalignment. Electric are used to reduce the cooling influence of cryogenic propellants.
The gear cases for the turbopumps in early Atlas and Thor engines were made in two halves clamped together by bolts. The bearing bores were line bored with the gear case assembled, and relocation of gear-case halves was obtained with dowel pins. Although adequate for the original design loads, the split gear case did not posses sufficient rigidity tn maintain gear alignment under the higher loads accompanying subsequent uprating. The solution was to redesign
the
gear
case as one-piece
construction.
Gear-case design must include provisions that minimize or eliminate internal fasteners (nuts, bolts, screws, safety wire, and snap rings) that might loosen or back out because of vibration during operation. Joints in the gear case are clamped tightly enough so that friction prevents relative movement of the surfaces. Recessed static seals such as O-rings are used rather than gaskets, because gaskets allow relative motion of the flanges and require more fasteners tn prevent bowing and leakage between fastener locations. To confirm design calculations, an instrumented gear case is subjected to full design torque while dial indicatars, strain gauges, or brittle
lacquer
detect
deflections.
In the development of a design that will satisfy the fixed nominal center-distance requirements, the effects of thermal contraction resulting from differing materials or thermal gradients are accounted for so that negative or excessive backlash or tip interference does not occur. Changes in center distance are compensated for in design by providing sufficient tip clearance to avoid interference at minimum previously, involute gears tolerate moderate variations modifications such as crowning of the teeth (sec. 2.2.5.5) are shaft tilt resulting from distortions of the gear case. Gear allowable gear stress levels are decreased to allow for the effects 6).
27
center distance. As noted in center distance. Lead employed to accommodate load capacity is reduced or of misalignment (ref. 8, sec.
2.2 GEAR DETAIL Adequate
gear
strength
depends
on tooth
size, pressure
angle
(see
sketch
below),
number
of
Base
circle
teeth, and deflections
face of
width. Tooth profiles the teeth under load.
fatigue failures. Rim and excessive deflection from
often are modified Surface textures
web proportions tooth loads.
Although the gear system configuration gear dimension may be necessary to spacing, speed ratio, and minimum Nonstandard center distances results of detail design may sufficient strength; the design
2.2.1
are designed
often satisfy pinion
to compensate are specified to avoid
both
for expected elastic to avoid scoring and excessive
vibration
and
dictates gear diameter, some changes in this the combined requirements of component size to achieve adeauate tooth strength.
sometimes are used to achieve specific speed ratios. The indicate that a change of diameter is required to obtain procedure is then iterated until a satisfactory design emerges.
Pressure Angle
Relatively high (25 °) pressure angles are radius of curvature reduces contact stress tooth. High undercutting
pressure angles also (ref. 10, pp. 14-17).
permit
favored for turbopump gears because the larger and the wider base increases beam strength of the the
28
use
of
fewer
pinion
teeth
without
excessive
2.2.2 The
Number
number (1) (2) (3)
(4) (5)
of teeth The The The
of Teeth is chosen
to satisfy
maximum
Contact contact
conditions:
the gear system. In cases of resonance, changes are system components, or damping methods are employed The pinion teeth must not have excessive undercutting. Tooth contact must not result in excessive compressive if too few teeth are used.
allowable
costs; the practical and maximize life, factors exist.
2.2.3
following
speed ratio shall be that specified by system requirements. tooth size shall provide bending strength adequate for the design loads. frequency of tooth meshings must not coincide with natural frequencies
Iteration of the design analysis analysis of root bending stress (refs. 3, 8, and 11) is performed The
the
Contact ratio ratio
number
is required until all the above and face compressive stress for each turbopump gear. of
teeth
is a function
limit is regarded as approximately the number of teeth in pinion and
made to the gears (refs. 21 through stresses,
conditions based on
which
or other 23). will occur
are met. A detailed the AGMA methods
of manufacturing 100. gear
of
and
inspection
To ensure hunting-tooth action are selected so that no common
Ratio
can be visualized as the average contributes to a smooth transfer
number of teeth of load from one
in contact. tooth to the
A high (1.5) next (ref. 10,
p. 55). In the Mark 4 turbopump (Atlas sustainer), a stub-tooth design with low contact ratio was replaced with a full-depth design; the resulting increase in contact ratio contributed to a great improvement in life and reliability of the gear set. A low contact ratio increases the severity of dynamic loads and causes premature tooth breakage.
2.2.4
Face Width
Experience has shown the gear pitch diameter. near the ends of wider mounted diameter. circular
that width of a spur gear tooth should be limited to 0.5 to 0.7 times The accuracy of alignment required to prevent load concentration teeth is difficult to achieve. Some designers contend that accurately
and machined double A rule of thumb used
helical gears can by some designers
pitch.
29
have a total face width is to limit the face width
twice the pitch to six times the
2.2.5
Tooth
Involute
gear
dimensional gears
Proportions
tooth
(ref.
24)
of gear
proportions
given
achieve
such
and
Summaries
for
necessary.
terms
complete
abbreviations
the to
(Pd
systems standards
of
involute
are given and
spur
made
durability.
definitions
2 (ch.
for
helical
with
standardized involute
gears gears
and
spur
(ref.
5). Modifications
profile
sections
terms
in 19.99)
high-power
problems
following and
= 1 to and
These
to particular in the
specified (Pd
in reference are
used
in reference
proportions
coarse-pitch
>__ 20)
solutions
symbols
compilation
by for
generally
strength
achieve
and
is given
defined
standards
fine-pitch
tooth
made The
are
as the
proportion in
maximum
compromises a more
profiles
systems
25). to the
in order
modifications are
used
are illustrated corresponding
only in figure symbols
to are
when t0; and
1.
Working
depth
tooth thickness
/_/_Q_
_
d, dedendT_
_ addendum
Figure
10. -
Sketch tooth
2.2.5.1
WHOLE
Full-depth tooth action is obtained that
the
scoring The
smaller
illustrating
terms
and
symbols
for
proportions.
DEPTH forms with length
(ht
__ 2.00/Pa)are
the
resulting
of action
higher
preferred contact
on a stub
tooth
for turbopump gears ratio. Some designers, (ht
< 2.00]Pa)
represents
risk.
following
factors
are considered
in determining
3O
the
tooth
whole
depth:
because smoother however, believe a reduction
in
• Strength •
Contact
ratio
•
Maximum
• Grind
fillet
stock
• Addenda
proportioning
• Sliding
velocity
• Availability
2.2.5.2
TOOTH
Tooth
to avoid
2.2.5.3
tooth
standard
of the
to provide
of the important undercutting,
design
required
often
both
desired
calculations
made.
backlash
2.2.5.4
strength
ROOT radii
are
have
shown
radii,
enlarged
balanced
strength
is obtained
tooth
strength
If pinion
and
tooth
by thinning
backlash;
modifications
the gear
teeth.
and
must
be
2 and gears
10).
made
in the
Figure
addendum
of pinion equalize
of pinion with
tooth
(3)
to balancing
undercut
(refs.
gear
undercutting
teeth,
for spur
maximized
the
to reduce
importance (20X
with
of fillet
to 100×)
by the
TOOTH-FORM teeth
and
to
and
gear
and
(2) balance reducing
effort
pinion
teeth
teeth,
(thereby
is decreased
satisfy
the
the The
equal
sliding
addendum
values
the
bending
maximum)
all three
strength.
achieving
11 presents
from
of these addendum velocities
required
to
20 ° PA.
FILLET
also is controlled fillet radii chosen.
2.2.5.5
gear
give priority
avoiding
developed
Fillet
eliminate
and
designers
for
equal
is increased
A compromise
most
been
to (1) pinion
velocities.
objectives;
Gear
achieve
risk
be established
addendum
requirements obtain
and
of cutters.
proportions
strengths
have
scoring
undercut
ADDENDA
Pinion
sliding
and
must
it is one
are made
to avoid
THICKNESS
thickness
therefore,
radius
loads
compensate
for
errors
deflections.
The
goal
root-bending-stress radii
layouts
manufacturing
are
(ref. made
method;
26).
concentration. To
determine
of the
gear
the gear
tooth.
tool
Photoelastic the
maximum
studies allowable
The
allowable
fillet
size
manufacturer
must
review
the
MODIFICATION in excess of is
to
of 1000
ppi often
manufacture, achieve
are modified
mounting a
perfect
31
from
deflections
involute
profile
a pure
involute
form
to
under
load,
and
tooth
under
load,
and
tooth
Ii i
I '
For
addendum
with
other
use
1.40
_
"_ II
value
based
of
gears
pitches,
+ Pd
on
ht
=
"_d
1.30
to prevent undercutting
•_
chart
Chart
dimension diametral
_ _.
_
1.2o Addendum
required
\,...
A
___
o" _.Io ......
"_ <
1.00
0.90
i ..... -...........
0.80
0..70 10
12
11
13
14
15
Figure
of
11. - Addenda teeth
modification
usually
Methods
for
concentrations
near
corrections making
(axial them
crowning may
the
ends
from
easing
is maintained,
reduction
of gear
load
modifications
torsional
windup
are used
to correct
being
of tip relief
teeth
30
40
60
vs number
of gear
80
125
considered
or a combination
that
in.
by
consist
of
near
on the
to 0.002
are
caused
thinner
crowning
the
design (ref.
greater
misalignment crowning
ends
loads
2, ch. than
of tip
presented
and 5).
0.0006
or
than
and
in
reference
are
minimized
end
in the
easing center).
expected
flank with
the
teeth
The
amount
misalignment.
In high-precision in. is avoided
relief.
27.
lead (i.e., of
Crowning
gears
where
because
Load
it results
good in a
capacity. also
on
25
gear
modifications
of
depends
0.0005
on
values for equal strength
form
modifications)
alignment
Lead
the
teeth
(20 ° PA spur gears).
required
circumferentially
or end
range
takes
calculating
20
17
Number
gears
scoring
are
used
with noted
face
to provide widths
in service
more
of 1 inch and
32
therefore
even
load
or more.
distribution Lead
are based
on
modifications on experience.
teeth
with
generally
2.2.5.6
SURFACE
TOLERANCES
Since
it is not
possible
axial
surfaces
(lead
dependent
on
application. sample
the
The gear
to produce profiles) gear
load,
allowable
a perfect
gear
allowed
to
are
speed,
and
deviations
inspection
charts.
Lead
profile
Involute profile surface texture
defined
and
and
surface, from
smoothness
are
Lead
tooth deviate on
involute
surface
tooth the
of the
involute
nominal
operation gear
surfaces
an
12)
by
which are
and
amount
required
drawing,
(fig.
profiles
by
the
includes
translated
by
texture
and
Tip
Hub
Root
Figure 12. - Sketch illustrating
terms for gear surfaces.
inspection machines to lines traced onto chart chart translates an involute curve to a straight from
a
perfect
profile tooth
or lead traces
restrictions that
involute
the
modifications are
determined
by
pitch
range
in the
on
of reversal the
readily
observed.
are reproduced
required
placed rate
are
to fall
the
involute (change
severity
of
within and
Desired on
the lead
the
of the
The
8 to 12 are as follows:
33
normal
profile
sample
tolerance
profiles
in direction service.
paper from the actual line, so that deviations
surface limits
tolerance
inspection
band
are that
gear tooth. The rolloff of the tooth surface
to
be
they for
charts not
should
power
gears
including
(fig.
acceptable.
should
trace)
bands
13); gear
Additional
be concave
not
exceed with
and a rate
diametral
-- Flank
r Db
(base
I
i
circl e)
I 4o F4 O
modification
Tip
TIF
I
D
(pitch
modification--
circle)
D o
I
I
• 003 • 002 • 001 .f.
'iL
• 001
/'//
©
O +O
.002 .003
_Tooth
_Degrees
roll
(a)
Involute
Limits
profile
from
base
rolloff
must
fall
within
these
limits
circle
chart
Tooth
_i_
Flat
potion
for
modified
profile
centerline of
tooth_
I
t'-
° f
i
Ill
I
/ii
! i
t'_ tl/
t t.t
°
.,-I > ©
t
Face
width
Face
,,
!
(b) Lead
width
-
chart,
crowned
FigUre
13. -
(c)
tooth
Sample
inspection
34
charts
for
Lead
chart,
involute
and
end-eased
lead.
tooth
|
Allowable Type of gear Main power (heavy loads)
0.0002
Accessory
0.0003
loaded
2.2.5.7
SURFACE
The
surface
gears
and
textures average)
satisfactory
service coarser
used,
but
limited
exceed
50
power
of both are
(arithmetic and
to 20 and
gin.
are
and
AA
within tend
testing When
active
carefully
finishes
gin.
peak-to-peak
and lightly
TEXTURE
therefore
finer
rate of reversal, in.
for any 25% of active profile
surfaces
greatly
design.
Roughness
for gear
tooth
contact
surfaces
the
indicates
production and
that
are
the
waviness
range
gear
by
to score
defined,
frequency
nonactive
controlled
capability avoided.
surface
been
limits
will
control
roughness
and
the life
of 6 gin. found
are
Both
not
height surface
of AA
to give
manufacturers.
peak-to-valley
specifications
between
have
of gear
Waviness
maximum
influence values
presently should
quality
the
rate
of
ends,
and
roots)
not in the
reversal
requirements. The
surface
effect
on
examples over
onto
have
roughness Other
gears
during
a
of noncontacting
fatigue of
maintaining Tests
quality
life.
active
Oronite
shown
that
ensure
that
the
a surface
roughness
process.
Scoring
than
marks
on
Reference
28
262)
lubricant,
oils. gear of surface design
Shot
lands,
tooth
and
gouging
lands
and
in the
tooth
discusses
but
texture goals
has
changes
increased
the
been
mixed vapor resulted
on noted
root
ends
has an fillet
are
not
lap
effects
of
must
beneficial
have
in marked usually
35
smoothed with
been or
operation.
12 gin.
AA out
roughness
in operation
blasting,
are achieved.
AA
gears
results
measurements
during
to 10 to
of 26 to 32/ain. occurred
has
peening,
surfaces
roughness
4 /_in. AA
improvement
the
webs,
tempering,
Similar
surface
with
noncontacting
surface
surface.
of less
run-in
(rims,
integrity.
values
diester-based Directions
marks,
conditions.
contacting
surface
Surface-roughness 2%
Tool
detrimental
areas
with
improvement are specified
grind
with
operation.
to 10 to 14 gin. over
32
fuel-additive
obtained
special
Surfaces during
with
AA.
(RP-1
plus
petroleum
control in gear
on the drawing
of life
AA
gin.
and critical
(ref. (fig.
28). 12) to
2.2.6
Rim and Web
Rim
web
and
designs
often
are dictated
by the
operating
vibration
spectrum.
Thin
webs (< ht)in particular are prone to vibration problems. Large radii are used to webs and webs to hubs to reduce vibration-caused fatigue failures of the frequencies
coinciding
web
mass
shape,
of rims
and
problem web
webs
that (fig.
operating and
sometimes
occurred
thickness,
surfaces
with
distribution,
forcing
is effective
on uprating
increasing
rim
frequencies
size, number,
and
in preventing
of the Mark
cross
section
3 gear and
are
shape
blend
avoided
by
of lightening
web train
fatigue was
radius,
altering
holes.
failures.
eliminated and
shot
rims
rim
peening
A web
fatigue
peening
the
14).
Whole in.
thickness-_
_'-
0.19
in.
radius
0.5
in.
radius
depth
-'---"
F
0.217
_
_
in.
F0.298
0.5
in.
radius
0.5
in. radius
I
I_
I
I
.
Shot I peen
I I
I
Web thickness
_
la)
Original
0,250
in.
(b)
design
Uprated
design
Figure 14 - Sketches illustrating rim and web dimensions (original and uprated designs)
36
and
Shot
by increasing
Rim
and
to blend rims web. Natural
the web
On
highly
stressed
power
adequate
power
resonant
frequencies.
proportion
tooth
between
the
changed Rims
capacity
manufacturing are
The
ease loaded
not
too
of the
thin.
natural
low
Normal
also
are
and
with
the
holes
often
and
to avoid
are given
as a
a weakness.
to a resonant The
normally
are placed spokes
dimension
achieve
For
condition
wheel
contour
was
was eliminated.
levels
the
to
are sized
indicates
traced
problem
that
web
frequency.
stress
to ensure
and
experience
were
mesh
low
circumferential
can be estimated
determined (ref.
diagrams
determine
on
minimized
if testing
gears
the
Lightening
of gears
resonances
Interference
based
are made
and
those
is taken
spoke
are
Rim
are
are sized
to achieve
in the webs
between
is from
of low-cost
the lightening
0.5
holes
to 115 times
the
size
holes.
frequencies
frequencies
and
dimensions weight.
II idler
frequency,
cost.
Care
usually
in Titan
natural
web
Changes
frequency
gears
and
gears.
lightening
observing
wheel
and
at minimum
depth.
natural
of small
rim
proportions failures
wheel the
the
stiffness
whole
breakage
webs
or lightly
tooth
gear
to alter and
and
The
of the
example,
gears,
whether
any
experimentally
21).
(also
by analytical
Sand
called
by
modal-shape
shaking
or "popcorn"
Campbell
methods, simulated
salt I is used
diagrams)
standing-wave
are
or
for
the
normally
actual
to reveal
plotted
frequencies
but
gears
mode
with
made
as large
and
patterns.
various
coincide
the
modes
gear
to
meshing
frequency.
2.2.7
Tolerances
As
of
part
the
consistent
effort
with
the
suitable
for
requires
tolerances
engine
different
modified summarized will
result
requires
power
class 10 in table in close
a
The
accuracy
than
the
the
limits
Ipopcorn evidence
liaison
and
and
require meet
which
with
gear used
chloride
that
frequencies
tolerances
The
entire
of AGMA tighter
class
limits,
cost.
coordination
established
spectrum than
Achieving
classes
aerospace
gears
14. In general,
other
aerospace
accessory
capabilities below the
as possible
tolerance
of current
9 through
while
manufacturing of the tolerances in
has
classes
tolerances
13
are
AGMA
rocket
power
gears
are
gears.
made
to meet tolerances values shown in the
the
levels
of measuring-instrument
of
accuracy
calibration
to are table
shown between
user. dimensions
tolerance,
of equipment is sodium
special
costs,
4). The
increase
the gear
manufacturing
salt
gears
limits. Present VII. Reduction
with
of vibrations
(ref.
gears
corresponding
the manufacturer
gear
reliability.
are a combination
power
turbopump
down
gear
applications that
turbopump
Most
to hold required
although
can
this ratio
for measuring is finer higher
than
table
than those
be measured
gears salt but that
37
is not
produced coarser
than
can be seen with
should always
be a factor achieved.
in quantity talc. sand.
The
smaller
of
Table
10 finer VIII
in production grain
size provides
lists runs, visual
Table
VII.
-
Gear
Manufacturing
Tolerances
on tooth
Tolerances
elements Finishing
Dimension
Hobbing
Involute Lead,
in./in.
Tooth-to-tooth
spacing
Whole depth Fillet radii Circular tooth Out-of-roundness
thickness
Concentricity Surface roughness,
gin. AA
Tolerances
Shaping
Journal Bore
concentricity concentricity
Journal-to-bore Tooth
element
concentricity concentricity
Grinding
5
3 15
3
2
15
15
30
30
30
5
5O
5O
5O
30
30
5
25
25
30 25
10 15 10
10
25
25
20
5
5
125
63
32
16
20
on gear body
3
2 5to
2
1
1
10
5+
elements
Grinding
method Grinding
and polishing
5
1
1
5
1
1
10
2
2
10
2
2
15
2
2
20
10
10
Taper Parallelism
5
1
1
20
2
2
Hub dimensions
20
1
Web dimensions
20
5
1 5
Rim dimensions
20
2
2
Fillet
50
lff
63
16
10 4
Surface
dimensions roughness,/ain.
AA
aExcept as noted, tolerances in this table represent ten-thousandth inch (2 = 0.0002 in.). bHighly specialized gear configurations for production measurement accuracy. 75 percent.
Honing
5
Machining
Journal diameter Bore diameter
method
Shaving
Finishing Dimension
a ,b
total ranges and are expressed in units of one
can be produced for specific applications to tighter valtles Rejection rate in this specialized field is seldom less than
CTolerances for honing are for corrective machining of values in excess of table values. Honing is not recommended for hardened rocket engine gears because of resultant surface texture.
38
c
Table
VIII.
-
Accuracy to Inspect
of Measuring Production
Equipment Runs
Used
of Gears a
Tooth elements Dimension
Measurement 1 0.5 1 0.5
Involute Lead (axial),
in./inl
Lead (helical), in./in. Tooth-to-tooth spacing Accumulative pitch Whole depth Fillet radii Pitch diameter Out-of-roundness Concentricity Surface roughness,/_in.
accuracy
1 5 10 2 2 2 (linear surface) 4 (curved surface)
AA
Gear body elements Dimension
Measurement 0.5 0.5 1 1 1.5
Journal diameter Bore diameter Journal concentricity Bore concentricity Journal-to-bore concentricity Tooth element concentricity
5 0.5 1 2 2 2
Taper Parallelism Hub dimensions Web dimensions Rim dimensions Fillet dimensions Surface
aExcept pressed
2
roughness,/aim
as noted, in units
accuracy
values
2 (linear surface) 4 (curved surface)
AA
in this table
represent
of one ten-thousandth
total
ranges
inch (2 -- 0.0002
39
in.).
and are ex-
•
_)
,.
Table
IX. -
Accuracy of Metrology Laboratory Measurements on Gears a
.-
Tooth elements Dimension
Measurement
accuracy
:7 i0:i1: b:i :•
Involute Lead, in./in. Tooth-to-tooth
spacing
Accumulative pitch space Whole depth Fillet radii Pitch diameter
0.1 0.I 1.0 1.0
Out-of-roundness
1.0 1.0
Concentricity Surface roughness,
_tin. AA
2 (linear surface) 4 (curved surface)
Gear body elements Dimension
Measurement
Journal and bore diameter, taper, roundness
0.05
Concentricities
0.1
and nor-
malities of journals, and tooth elements
accuracy
•
bores,
?
•
Hub, rim, web dimensions Fillet dimensions Surface
aTable formed calibrate
roughness,/aim
lists the accuracy on gear elements• production
ten-thousandth
AA
2 (linear surface ) 4 (curved surface)
of measurement
(in inches)
These
measurements
measurement
equipment.
inch (2 -- 0.0002
in.) unless
40
that
are used
can be perprimarily
Units
shown
otherwise
noted.
to
are one
.,.-
while The
table
IX presents
laboratory
2.3
the
equipment
limits
achievable
is used
in the
primarily
most
specialized
metrology
to calibrate
production
measuring
equipment.
MATERIALS
2.3.1
Gears
The
materials
gear
practice
used
in turbopump
with
some
gear materials suitable the basis of chemical A summary
of the
gear
additional
systems
materials
used
are
refinements.
for lubrication by rocket compatibility rather than
Table
Materials
gears
to those
attempts
propellants; strength and
in turbopump
X. -
similar
Some
Application Critical,
highly
loaded
Gear matirial i _ower gears
AMS
265
in table
Moderately
loaded
gears
AMS
260
dlL-L-6086
oil
Used where
oil
are required;
Same
oil
;20
AMS
470
Propellant-cooled or lightly
gears
gears, moderloaded
Lhe
above, AISI
dus 340
AISI
140
AMS
;260
AMS
;265
AISI
.40C
copper (Berylco
aRP-1 plus Oronite 262 (2 to 3% concentration
tm
Used for accessory
LH2,
LO2, RP-1
Gear material corrosion
Gear material
N204
corrosion
diamine, LH4,
GH2
in service, up to 10% during run-ins).
41
than
must have
from
gears.
must be protected
from
by moisture.
LH2, LO2, IRFNA,
Ethylene
re-
to avoid edge
must have protection corrosion.
as above
UDMH, N_H4, 25)
less critical
edge radii
Same
status
Bery
and reliability
protection
Used for wear resistance; smooth
Any
corrosion
Used in applications those above.
as above
chipping; moisture
loaded
high capacity
a
(nitrided)
-Lightly
Xi
quired.
AISI 9310 AI5 ;20 AISI
aircraft to select
Comments
MIL-L-7808 Fuel-additive
for made
Gears
Lubricant/coolant
MIL-L-25336
been
these materials were selected flare very limited usefulness.
is presented
for Turbopump
developed
have
i _1
ately
laboratories.
very brittle;
resistance;
has some
in experimental
only.
Gear material
low in hardness;
herent corrosion mental status.
resistance;
has in-
in experi-
on
Deep-carburizedcase-hardenedsteelssimilar to vacuum-meltedAISI 9310 (AMS 6265) have been found to possessthe best combination of properties for power gears;the hardened outer surface resists compressivestress and wear, while the tough ductile core provides resistance to shock loads and has good resistance to bending-stresscycle fatigue. Use of vacuum-meltedsteelhasextended the fatigue life of gears. The useof corrosion-resistantmaterials for gearshas beenlimited to experimental programs, because no corrosion-resistant material possessesthe combination of hardenability and toughnessrequired for highly loaded power gears.The 300-seriessteels and the Inconels cannot be sufficiently hardened to withstand high compressivestresses;in addition, these materials tend to score and gall excessively.The truly hardenable stainlesssteels,such as 440C, are too brittle to withstand dynamic tooth loads. Beryllium-copper alloy carl be heat treated to approximate the tensile strength attained in the core of carburized steel gears,but the surface cannot be hardened to withstand the compressivestressesencountered in power gears.The lower modulus of beryllium-copper alloy allows greater bending deflections but at the same time reduces the peak stresses causedby dynamic loads. In one experimental program (ref. 18), nitrided 410 CRES was tested as a candidate gear material that would combine corrosion resistance,a hardened surface, and a ductile core. Although the gearswere superior ro 440C gears,the extremely brittle hard casechipped at the tooth corners.
2.3.1.1
To
MATERIAL
obtain
many
the
details
GRADES
load
capacity
of
the
carburizing
steels
AGMA
recognized
has
vary
and
reliability
manufacturing over the
a wide need
1 (minimum
quality
are acceptable.
Grade
2 (normal
Rigid inspection quality is in fact
quality).This
the
for
Process
control for aircraft
All
material
properties
be and
gear
on
accessory
two
tight;
heat
lots and
properties specified.
grades
of The
are defined
been
defined,
small
deficiencies
and
a
in
gears.
required
control (aircraft quality) guarantee grade is used in aircraft power gears.
42
The
have
is moderately
steel
the grade
processes;
materials
are
gears,
specified.
depending
materials
aerospace
is used
quality).-
must
extent
grade
and process achieved. This
for turbopump
processes range,
for grading
in reference 3. Three grade levels fourth appears potentially useful: Grade
required
to
meet
that
the
high
standards.
specified
high
Grade
3 (premium
can
presently
and are
process tested
provide
no
power
expense
is spared
of parts,
2.3.1.2
to
mill
achieve
lot
the
control
are employed.
achieved
gear. The is allowed
strength,
composition
bought
in registered
Compliance
it is expensive randomly of steels
that
gear
to achieve.
chosen parts is specified.
manufacturers
Rigid
inspection
out of production runs This grade is used in
can be manufactured
optimum.
of the
Reduction
case and
core
hardenability and
steel,
Rigid
laboratory
process
analysis,
in cost
will follow
are major
factors
a representative
the
by present
technology;
inspection
and
and
more
in the
of the
of AMS
random
widespread
process
destructive use.
strength
and
durability
of a
a vacuum-melted
(H-band)
is based
on end-quench
Alloy
carbide
banding
solution because
temperature required. Vacuum remelting of the smaller mass of a vacuum-melted
2.3.2
Gear Case
Gear-case
often
materials
The
compatible
with
(such
as
are included
are
materials
chosen
must the
of
coefficient
of thermal
light
be strong,
weight
power
low-alloy
to
the
gears
are
carburized
is documented
and
hardness-traverse
steel.
certified tests
by
made
on
fabricated,
environment. Tens-50)
is
considered (sec.
to
2.1.9).
43
used
rigid
hot
soaking because
structure
dimensionally
Lightweight, are
by
to this process
to induce of the high
specifications.
a lightweight,
easily
reduced
has a beneficial effect in reducing banding ingot. Requirements intended to reduce or
in gear material
or
expansion
been
is not amenable
to provide
service
A356-T61
advantage
banding
has
of alloy
banding
in addition
into nearly parallel bands aligned in the direction on material properties and thus is considered
solution
eliminate
limits
specified
for turbopump
lot of steel.
materials.
bands;
are
Materials
6265,
of alloy constituents has unknown effects
in gear
(H-bands)
requirements.
hardenability
certification
sample
Banding (segregation of metal working) undesirable
lots
specified
producer;
tolerances
cleanliness
mill
to the
steel
alloys
aircraft-quality
hardenability is dependent partly on the chemical composition of the steel, which to vary within limits specified by the material designation. To ensure attainment
adequate
gears.
that
PROPERTIES
in the
material
the
grade
quantities;
- Best material
METALLURGICAL
Hardnesses
of
material
in production
quality).
including
testing
Best
gears.
4 (ultimate
control,
-
control are required. In addition, destructively. Use of mill lots
turbopump Grade
quality).
for
outweigh
stable,
high-strength most the
for
turbopump disadvantages
mounting and
castable gear of
the
chemically aluminum cases. the
The larger
Magnesiumalloy has been used for to avoid
electrolytic
also has been
2.4
a problem
of the
therefore
with
fabrication
must
to maintain
magnesium
2.4.1
by alumimun steel inserts
gear cases.
be considered
are
designed, forging
gear
For
maximum
High-energy-rate webs, to the
rims,
desirable
material
responsibility.
as forging
flow tooth
from
and
gear,
forged
bar stock.
but
the
outer
after
peening;
their
properties
It is especially
shot
effects
these
and
important
processes
cannot
the
hubs.
has
Tests
of the
dies.
have
be verified
by
approximates
been
used
to forge
run
on these
around
gears
the
by gear rolling
and the
gear-tooth-root
teeth
are
of the blanks
increased fillet
used
are made
is made
(refs.
a
than
cut
in the
finished
gear
including
gear
strength
to improve
in
from
in all dimensions the
gear
shown
also has been
gear
outline
complete have
orientation;
gear forgings
to 1/4 in. larger
flow
grain
A typical
is removed
grain
metal
forming
1/16
stock
to improve
power
forging
is made excess
in order
turbopump
closed
shape
forging,
blanks
Most
dimensioned
forging
and
grain
31 ). Plastic-flow
from
strength,
teeth,
2.4.2
made
shape;
shape.
17, 29, grain
and
life
30,
and
flow.
Tooth Cutting
teeth
are
carburized,
cut
obtained
by
to obtain
in a blank
hardened,
hobbing gear teeth machining methods
cutting
to attain
designer's
such
of the
are made
accurately
in which
finished
pitch
of the
performance
gears
gears
specially
Gear
part
of processes
on the testing.
turbopump
noncritical
blank.
is necessary
Forging
Critical
blank
processes
consistency
great influence nondestructive
due
gear cases but generally has been replaced consequent corrosion. Retention of threaded
and
FABRICATION
Control
the
action
and
diameter. a range
hobbing, It
shaping,
is easier
than by other means, but must be carried out with
hobbing.
the
by
finished.
Short-pitch
maximum These
undercut hobs
of number
on gear tooling design. specialized tooling.
must of teeth,
Gear
tool
hobs
or
to
fillet
be
designed
radii
often
44
used
while for
as are standard suppliers
grinding
a superior
a specific hobs.
in preshave
providing Reference
can furnish
capable
the
is required. the surface grinding
and
are not
10 presents consultation
gear
texture
and pregrind
some gear
before surface
more axial cutter clearance additional care to achieve
are sometimes
and
green
obtain
is by
Other texture cutting
stock
at the
suitable
for
information as well as
Shapingof gearteeth is usedprimarily when gearsand splinesare in axial proximity to other components. Shaping generally does not generateas smooth a finished root ashobbing and therefore is the secondchoice of tooth-cutting methods. Grinding in place of a cutting operation often is called."green grinding." Greengrinding of tooth forms from solid blanks is possible when gearsfiner than 20 pitch aremade; coarser pitch gearsgenerally require some type of pregrind cutting operation. Green grinding of complete gear forms has some advantages;it is used to obtain a slightly better texture, especially on hard materials, and may be required for materials that work harden. Green grinding is not usedin producing turbopump power gears.
2.4.3
Heat Treatment
Power
gears
are
Carburization environment; Critical conditions
of
time,
into
content.
heat
carburizing
and
2.4.4
Most
gears
thereby
shaft.
Generation
roots removed
are
the
only
grinding
to obtain
roots
ground, from
brittle
case.
the
to
also
wear-resistant
has
atmosphere
a desired the
in
that
are
potential
for
by nitriding
it is more been
gradient
of areas of
be obtained
not
32.
controlled
carburizing-medium
because but
teeth.
in reference rigidly
carburization
may
the
carburizing
obtain
surface,
Nitriding
given
and
of
is avoided
hardening
are
under
to prevent
copper
Case
finished Form
requiring
is used are
is used
the
a superior
the
a small
used
the
expensive for
than
turbopump
critical
grinding
in order
has the
amount with
to obtain
advantage
of axial
larger
clearance
wheels
the
of permitting and
between requires
best the
texture
parts
more
and
use of a small on
the gear
generous
axial
clearance. the required
of accessory care
by
grinding
is done
to give grinding-wheel
addition,
materials, is used
of
high-temperature
Finishing
to tolerances.
wheel,
Grinding
AGMA
concentration often
durability
carbon-rich
gears.
turbopump
spacing
embrittlement.
by
a
furnace-wall
frequently of
surface
to
carburization
cycle
in a more
the
parts
gas-type
carbon
stripping
results
Tooth
conformance
plating
produces
main-power-train
to
heat-treatment
Acid
process
the
increase the
recommended
subjected in
Copper
hydrogen
This
to
exposing
temperature,
the
treated.
introducing gears.
are
Variation
programmed
carburized by
procedures
gears
composition.
not
case
obtained
carburizing
power
carbon
deep
is
must area
and be
accuracy lightly
taken
of the
root.
to
of all critical
loaded
power
ensure
that
Sometimes
45
contacting
gears
generally
a minimum only
the
profile
sides
surfaces.
are ground.
of hardened of noncritical
In
When stock gears
is are
ground, and a greater blending tolerance may be made between the heavily loaded avoid removal by grinding
The due
in the
ppi) case,
roots;
grinding
Residual
tensile
stress
this area
is loaded
section. service
(above 2000 of hardened
turbopump gears, unground as it is difficult to determine also induces on
factors
contribute
gear
size,
induced
in the
to gear gear
The
parts
then
quenching limit
on
areas
(zone
than
gear the
may
fillet,
zone
residual
roots
Grinding
not
Shot
are
that
the heat
undesirable
may
be
in the root
desirable,
defined
that
the
loaded cause
heat
on
flow
produces
entire but
depth
ground;
surface no
since
in
this
the
is cleaned. steps
area
on accessory
may
(fig.
hubs).
sometimes
to 0.005
in., the
approximately
15).
The
gear
conforms
B, between risers
from not
and
20
grinding.
surface
Zone
or stress
is protected gears
is made
is
by carburizing
(webs
distortion;
for finish
factors stresses
generally
gears
only
to 0.003
gears
These
Distortion
areas
entire
contacting
unrelieved
in large
depth
hardened
of the
and
minimum
to allow
that
sharp
hardening.
is controlled case
critical
and
is reduced nonhardened
to ensure
percent
treatment.
from
"as-carburized"
completely
100
technique,
Distortion
"as-finished"
Grinding
of lightly
abuses
The
is not
stresses.
of wheel grit, coolants, burns on finished gears.
2.4.5
size.
that
carburizing
Distortion
carbon
purpose.
be ground;
C, normally
tensile
in the
and
or may
this
ensure
preceding
width. the
desired
of grinding
dimensions
root,
face so that
for
A, fig. 15) is ground
design
For
are specified in order to amount of case removed
stress
surface
heat-treating
processes
and
to
during
design,
removing
are used
deeper
Three
distortion
are quenched
dies
depending
percent
size
and
is allowed
forging
manufacturing
the
complete
to
shape,
proportional
profile
roots.
for grinding stock depends on the amount of distortion of the gear heat treatment. Ideally, the minimum amount of case should be
removed. Enough grinding stock surface of each tooth is finished.
include
tooth
tensile
and
in compression.
required allowance to processing and
Many
a gear
a residual
roots the
profiles
the
profile
and
The
root
are allowable.
grinding
be critical
and
profile
to required
the
and may
resulting
be allowed
gears. retempering
feeds,
and
and speeds.
rehardening
Nital-etch
can be avoided
inspection
is used
by proper to check
selection
for grinding
Shot Peening
peening
increases of shot peening
of
tooth
surfaces
130 to 400 percent terms and processing
and
other
gear
surfaces
have been in detail.
noted
(refs.
46
extends 33
and
gear 34).
tooth
Reference
fatigue
life;
34 defines
_
Outside
diameter
\
\ Zero
/
blend
Zone
/ / /
Zone (grinding
lines
B
(transfer from profil e to fillet; grinding and honing may or may not be present)
A
or honing)
/
\ \
/ Specified fillet radius
-_
Zone
B
Zone
C
Contact
/----"No
Blend
radius
(both tions
configuraacceptable)
diameter
grind"
diameter Point
(no grinding
of
or honing)
of
Blend tangency
tangency I_
/-_Root
Figure 15. --Sketch illustrating hardened gears.
The root fillets of gears are peened the effects of surface discontinuities
Gear rims and in tool marks,
webs nicks,
of critical and other
Shot the
peening surface.
is known Shot
to retard
peening
before
grinding zones on critical
to increase the of the teeth.
residual
gears are shot peened surface imperfections
significant increase in the average fatigue to the effects of shot peening the web.
plating
helps
cracking prevent
compressive
to prevent that may
life of the Mark
stress-corrosion
diameter
by reducing plating
47
and
to reduce
fatigue cracks from forming occur during manufacture. A
3 gear train
the base material; however, it is not a substitute for reducing baking the part. Multiple peening the same part with different-size
stress
cracks
was attributed
the from
tensile
in part
stress
extending
on into
embrittlement potential by shot has further increased
fatigue
life
creates
a very
under exhibited steel
The
by
shot.
effectiveness
size
that
Corrosion when
appears
to
depends
on and
or
and
failures
fretting
steel
of
preparation are
the
surface
of
before
detrimental
have
cast
performance
the
have
parts
non-corrosion-resistant
lubrication
a gear
to
stainless
greatly.
on
peening
shear
resistance
is not increased
scale
intense
subsurface
Some
with the
extremely
reduce
glass.
peened
improve
roughness
that
will
resistance
steel
resistance
oxidation,
indication
stress
stainless
surface
indirect
test
strip
method (a
thicknesses) holding
an effect gears
is used
piece
of
on
the
indicating
the peened
to the
required
subjected
For
achieve
achieve
the
and
iron active
peening.
are
removed
necessary
•
A data
•
Sample involute with limits
•
Sample
•
Rootfillet
design
turbopump
gears,
of
time 98
long,
work
a peening
in one
of
When to the
for
released
surface.
standard from
the
compressive
of 0.015A
--.001
It is expressed the
An Almen
three
residual
callout
= 0.051
is specified. of
treatment.
piece.
in height
(thickness
percent
controlled
is used,
in.). as multiple
Turbopump
of the gears
are
Control
of gear
include
three-view
document
3 in.
as the
in. for an A strip
control
A detailed
quality-control
wide,
peening
is therefore
of a shot-peening
an arc proportional
indenting
that
•
lead
in.
and
MIL-S-13165.
of 4N:
to specifications
block
effectiveness
an exposure
Configuration
or refers
effectiveness
specification
3/4
same into
of 0.015
to an exposure
2.4.6
the
arc height,
to
steel
bows
side.
an arc height
In addition
to gage the
to
strip
on peening
by invoking
spring
is exposed
fixture,
stress
has
of turbopump
An
to
33).
with
peening
uniformity
processing
This
of
is some
peening.
Shot
To
the
decarburization,
before
(ref.
peening
that
There
compressive
corrosion
Light
provided
Minute
36).
peening
decreased
surfaces
and residual
stresses
increased
time
35
deep
compressive
been or
(refs.
drawing
(see table
(figs. (fig.
is essential personnel.
physical following of the
characteristics,
the
gear
drawing
of roll from
base
circle
includes
items:
gear
XI for an example)
roll-off
chart detail
the
chart 13(b)
based and
on degrees
(fig.
13(a))
13(c))
15) in conveying Reference
the 2
requirements.
48
(ch.
designer's 11)
intent
discusses
to the gear
manufacturer
drawings
and
and data
Table
XI. -
Sample
Data Block
for Gear
Drawing
Turbopump gear dimensions (representative values) Tooth
element requirements
Power gears
Number of teeth
33 11 25 3.000 ref. a
Diametral pitch, in.- 1 Pressure angle, deg Pitch diameter, in. Involute form (profile) Base circle diameter, in. Outside diameter, in. Root diameter, in. True involute form (TIF) diameter, in. Fillet radius, in. Addendum, in. Whole depth, in. Circular thickness at pitch diameter, in. Measuring pin diameter b , in. Measurement over pins b , in. Maximum involute profile error c, in. Maximum cumulative pitch error (any two nonadjacent Lead error, in. per in. of face width Tooth-to-tooth spacing error, in. Crown, in. Rate of reversal, inches in any 25 percent Backlash when assembled, in. a"ref."
means
dimension
bThese
values
may be established
CAll gear values
2.5
2.5.1
for reference
+0.000
5.966 -o.oos 5.664 ref. 5.720 max. 0.025 min. 0.0667 ref. 0.150 max. 0.1269 ref. 0.14400 ref. 6 ,_,_+o.ooo
.,_,-ti -0.002
2.803 ref. 2.890 max. 0.028 min. 0.1205 ref. 0.219 max. 0.1650 - 0.1677 0.17454 ref. 3.3117 - 3.3167 teeth)
.u_-_.O.O06
+0.0003 (see chart) 0.0015 0.0003 0.0003 None 0.0003 0.006 - 0.010
(see chart)
0.0002 (see chart) 0.0002 0.0002 (see chart) 0.0002 0.003 - 0.007
only.
by the quality
from
70 12 20 5.833 ref. standard 5.48152 ref.
modified 2.71892 3 -_1+o.ooo
+0.0002 0.0010
gears
assurance
the axis of the part
department
and may not be included
as designated
or from an axis determined
in the gear drawing. by its mounting
diameters.
TESTING
Acceptance
Quality-assurance severity
given
are measured
Accessory
of
tests service,
Testing
for the
gear
acceptance
reliability
depend
required,
49
and
on
the the
gear service
property history
considered, of
the
the gear.
Quality-assurance 100-percent
requirements inspection,
(1)
All gears
for
sampling
inspection,
are subjected
• Dimensional
turbopump
to the
check
• Magnetic
of case and
particle
• Surface Heat-treat
etch
as summarized
of
below:
texture
cracks
magnification
gears
and
flaws
if required)
presence
or sample
a combination
core
for
to determine
specimens
are
checks: surface
exposed
inspection
gears
certification
including
• Visual inspection (with other surface flaws (2)
and
following
inspection
• Hardness
main-power
of surface are
for nicks,
tempering
tested
tool
from
destructively
marks,
grinding
for
the
and abuse
following
metallurgical properties: • Case hardness • Core
hardness
• Chemical
composition
• Case depth • Microstructure (esp. • Retained austenite • Hardenability • Cleanliness (3)
Intrinsic
(may
qualities
certification
for
grain
• Heat 2 (ch.
size and
no
manufacturer)
banding)
by steel tests
processing
by steel
manufacturer)
exist
are
ensured
by
control,
etc.)
process
control
and
for
peening
• Hydrogen-embrittlement • Material source
Reference
be certified
be certified which
of proper
• Shot
(may
treatment 23)
relief
(type
presents
a
(if required)
of furnace, discussion
dew-point of
gear
inspection
and
the
devices
for
gear
inspection.
2.5.2
Performance
Testing
has
been
used
turbopump
power-gear
that
and
supply
accurate, torque tester formed
and
losses;
thus
tester
driven
systems:
the
to procure
of speed.
a fixed two
by a 100-hp
trains
of several electric
such and
One
torque
gear
a gear load
as a design Several
full power
expensive
in which by
extensively
absorb
as a function
Testing
of the
is locked (fig.
types
diagnostic
run.
Other
most
useful
by torsional tester
horsepower
motor.
50
tool
devices
as dynamometers;
16). The
thousand
and
of loading
these
devices test
use
devices
loading
fixtures
windup prime
in the
of the mover
development
are used, are
methods
has been shafts need
can be simulated
including
the into
supply with
of those
sophisticated, that
impose
back-to-back a closed only
loop
friction
a back-to-back
Driving po_er
Static torque is applied to the coupling and maintained by inserting shims at A
Loaded side of teeth are shaded
Figure
16. -
Sketch
of gear arrangement
in a back-to-back
gear tester.
The used
back-to-back in
the
gear
vibration,
fatigue,
example,
lubrication
simulated prior to
by evacuating starting the
circulation Gear and
and
the test.
feed
gear data
from
expense only
to run-in
back-to-back High-speed
been
for initial
from
obtained
gear
case assemblies)
problems
ambient
in profile
and
solutions during
vehicle
flight
of a new
51
data.
increases, system
hot-fire Since and
and
system
For were
pressure of 2 mm Hg to observe lubricant were and
at each
engine
adequacy.
in a gear
to the difficulties
turbopump
has been
modification,
material
pressures
gear enclosure to an absolute motion pictures were used
information testing
of
uniformity,
low
Successful
telemetered
of gathering
production
correction
processing
arising
behavior. have
used
ultimate
limits,
problems
occasions and
back
tolerance
data
difficulty
(also and
foaming
operational on rare
tester
identification
static
higher
flight
for trouble
developed. engine
tests
assembly
the
tests shooting.
are used
to
C'-I tt_
3. DESIGN
CRITERIA
Recommended
and Practices
,
3.1 GEAR
SYSTEM
Th[ _ gear
systenz
sl)acing, The the
gear
capacity,
mal_e
gears,
manifolds,
and
volutes,
requirements
of power,
design speed,
designer
showing
bearifigs.
the
The
must
lag.
lmp.or.tanti.:•decisions
concerned Initial
in order
estimates
evident
and
cycle may incorporation As the such
of
the be
gear
gear
on
lubricant
for
clearance
for quill
assembly.
case
be met
of
proper
selection
overall
turbopump
system,
used
with data
as the
timely
The
attention
accessibility power
should
be 'performed
and
the gear minimum to
influences gear
design to
those
reference. become selection
systems
be directed and
ducts,
stage.
design-configuration
of fasteners,
must train
design
of
distribution
for future
of
size of pumps,
positions
intercomponent
proceed.
firm,
stackups
in the
and
the
at this preliminary
to provide
that
by
cross-feed of information between design adjustments are made with
modified
becomes
to ensure
for
of rotation, design
documented and
can
responsible
direction
gear
calculations
Tolerance
shafts
and
by
toward
details
of special
tooling
ensure
adequate
axial
accessories.
Speed Ratio
the
gear
Perform
accessory
hydraulic recmirements
pump
shall
system weight
considering hardware practices in selecting Design
be
o./ rotation,
turbopump
by a review of previously used or existing elements already shown to be successful.
delivery
The gear system
speeds.
be
effort
may
configuration
required
Design
size
direction
of the
life
be considered
should wasted
detail-design
shortened of design
gear-system
as the
3.1.1
to avoid
and
primarily
The respons.ible project engineer •should ensure designer and other specialists so that •necessary time
speed,
layouts
position,
effect
and .accessories
for
rigidity.
preliminary
mechanical
lay'o_!ts
and
the
mozmting
review
size.-The:
should
satis./)_
requirements
and
turbine,
i ....
shall
should
system
type
design
load
designer
gear
gear
"-.
satisfy to have and
the
turbopump
a speed
efficiency
or the
for speed,
ratios
to obtain
electric and
to
results
53
Air
speed
ratio.
in optimum the
turbine
optimum
improvements.
required
Observe
tolerance
for
determine
consumption reference 37.
the speed
generator).
for speed
that
studies
weight and propellant system speed; consult
gear
ratio
requirements
for the Force/Navy
if required.
specific
and
pump
configuration
For recommended
accessory
Design
(AND)
(e.g.,
the
Standard
The
reduction
number
ratio
of each
of reductions
mesh
should
reconnnended
be kept
for overall
the (1)
following
sequence
Choose
the
change
within
the spacing Determine
(2)
Check
(4)
Enlarge
3.1.2
limits
requirements whether the
minimum (3)
the
gear
number tooth gears
proper
pinion
as necessary
indicates
tile
Planetary
gear
diameters:
diameters
maximum
(sec.
by the
table
ratios:
that
reduction
3.2.2).
methods
to achieve
will
Increase given
(a) achieve ratio
of pumps and turbines. pinion diameter chosen
of teeth
strength
following
2
the
and for
reductions
1
to determine
mininmm
5. Tile
I,to412to9 i 3to12 i
Overall gear-train ratio Number of reductions
Utilize
below
per
the
pinion 3.1.7.
life
mesh
and
accommodate
in section
acceptable
the desired
and
(b)
the
diameter
speed satisfy
required
if required.
reliability.
Speed Capability
The
gear
s:,steln
shall
operate
satisfactorily
at
the
speed
required
in
the
apl;lication. When
possible,
Higher
spur
speeds
gears
require
characteristics,
should
be designed
special
lubricant
for pitchline
attention
to
and
details
capability,
velocity
measurable of
and
tooth
design
less than
20 000
inherent
gear
in
order
ft/min. quality
to
maintain
be
given
reliability. When
PLV
hibricant
in
a gear
delivery. •
Direct
the
velocity •
design
One
or more lubricant
(speed
exceeds
10 000
of the
following
stream
and
direction)
tile pitch line of the tooth Use baffles and deflectors scavenge
oil thrown
from
of the
the
14-1)
or that
than
25 000
velocities
in reference
to
of the
stream
mesh.
Ensure
is sufficient
that
the
to penetrate
to
the
teeth
and
to
teeth.
face overlap of at least 2 in preference Minimize the sliding velocity between sec.
greater
sliding
side
must
be applied:
as it passes the jet (refs. 20 and 21). to ensure delivery of lubricant to
•
Calculate
lubricant
attention
should
disengaging
In designs
less.
PLV
special
practices
•
or
with
to the
ft/min,
use
double
to spur gears. gear tooth surfaces, by
the
10 (p. 55).
54
ft/min,
method
shown
helical preferably
in reference
gears
with
a
to 60 ft/sec 2 (ch.
14,
Sliding
velocity •
can be reduced
Use
the
smallest
bending
(sec.
Minimize
•
Use a large
•
Use long addendum
pitchline
of the
following
practices:
pitch
that
result
will
in a gear
with
adequate
root
3.1.7).
velocity.
pressure
angle
(25°).
of driving
pinion
(sec.
3.2.5.3.3).
Gear Type
The gear Involute and
diametral
strength
•
3.1.3
by any
spur
accessory
whenever
type
shall
gears
on
drives.
be suitable coplanar
Utilize
for
the application.
parallel
shafts
speed-reducing
are recommended gear
trains
for most
rather
than
main-power-train
speed-increasing
designs
possible.
Involute
helical
or bevel
gears
are
suitable
choices
for
accessory
drives
when
the
loads
are
light. For applications that recommended because balanced gears
axial-load
should
3.1.4
exceed the capacity of spur they have higher load-carrying
component,
be coordinated
and
with
smooth
potential
gears, capacity,
operation.
The
double higher
decision
helical speed
to use
gears are capability,
double
helical
suppliers.
Gear Mounting
The
gear
mounting
method
shall
provide
accurate
location
and
alignment
of the
gear. Utilize and
straddle
gear spans
mounting on deflection
casing
deflections,
shown
in figure
that
the
clearance.
in preference
and
bearing A highly
calculations
thermal
3. Place mounting loaded
to overhung that
effects.
an overhung surface gear should
mounting.
account
for shaft
As a general gear as close
can
be
rule, to the
machined
be made
55
Base
integral
follow nearest
properly with
the
bending, the
bearing minimum
bearing by
its shaft
selection
deflections, proportions
as possible.
providing (fig.
of bearing
4).
adequate
Ensure tool
3.1.5
Gear Attachment
Relative
of" the
motion
gear
and
shaft
shall
cause
tzOt
excessive
deflections
or
fretting. Make on
the
gear
the gear
the
integral
shaft,
raceways
raceway
with
if feasible,
are
the
pilots
as those
When
straddling
the
spline
Provide
shall
sufficient
not
become
backlash
Center
•
Gear
distance
• • •
Bearing eccentricities, Gear eccentricity Gear tooth thickness
•
Gear
tooth
design
tooth
may
be
the
changes
bending
spacing
provided
gear
must
races.
The
heat-treatment
teeth.
See
reference
removable
from
be
to locate
the
under
gear
38
of
for recommended shaft,
Transfer
web.
races
requirements
the
gear radially.
the
inner
utilize driving
Figure
two torque
5 presents
the
gear
Load Capacity
steady-state
Preliminary
from
capacity
caused
gear
contact
In selecting
the
by thermal
reduce
increasing
on the
minimum
contraction
minimum
center
is used,
nondriving
side of the
backlash,
of the gear
theoretical
the
than
loads
of the
the
pinion
long addendum
from gears
distance
or
it is recommended
shall be adequate
designs
tooth
consider
the
case
gear
center
distances
tolerance
rather
3.1.7
Gear load
film.
which
by
tooth
arising
to prevent
deflections
addendum
balance
12).
the
roller-bearing
tolerance
strength
Calculate
for gear
Incorporate
negative.
by
•
a long-pinion
thinning
separate
centered
teeth and to allow for a lubricating effects of the following factors:
Backlash
possible.
Backlash
Backlash
When
when
the gear web
by a loose-fitting involute recommended configuration.
3.1.6
shaft
to eliminate
same
configurations.
tight-fitting
the
tooth.
torque
and
pitch
be roughed
56
reducing backlash
Otherwise,
will be lost (ref.
to transmit
may
by that
part
be of
thickness. obtained
the
by
improved
2, ch. 5).
the design
loads.
radius
as outlined
out
tooth
by utilizing
in reference recommended
2 (ch. values
of unit
load
design
for
satisfies
3.1.7.1
bending
the
TOOTH
The
gear
criteria
ROOT tooth
required
service
Use
the
load
and
layouts
face
stress 3.1.7.1
root
for root
bending
XII.
-
3.1.7.3
possess
compressive set forth
adequate
the applied
load
for
stress.
limits
shown
Preliminary
bending
in table
Design
strength
For
reverse
loading
to 0.7
applying
modifying the
calculating (1)
loaded
values
factors adequacy
the bending
Y for
highest
point
design
calculations
XII for preliminary
Limits
for Face
Load
and
Unit
Load
Face load, ppi
Unit load,
AGMA 1
7 000 2 500 1 500
42 000 25 000 12 400
AGMA 1 or 2 AGMA 1 or 2
1 000 500
12 000 6 000
3a or better AGMA 2
to that
used in aerospace
stress
in both
shown
gearing
of the
diiections
in table
to account
psi
but
has not
been
adopted
as
XII.
of rotation), The
for dynamic preliminary
reduce
preliminary
loading design
(ref.
selected
design
the must
allowable
load
be refined
by
8). on the
basis
of unit
load
by
as follows:
out a large-scale (10× leads to the selection
finding
the
by AGMA.
(gear
of the
strength
Lay that
is equivalent
designation
capacity
Check
grade
to achieve
steel gears
train
material
gear
strength.
Main-power train Accessory drive Nonlubricated (propellant-cooled) Noncryogenic Cryogenic
an official
the
loads.
Gear service
aThis
that
below.
Material grade for carburized
Main-power
Verify
STRENGTH
shall
unit
K values
through
BENDING
life under
and
Table
and
turbopump of single
to 20×) of the gears
tooth
tooth profile to select the tooth geometry factor J. A detailed
is given
contact
(fig.
57
in reference A-l,
ref. 8).
8; base
Y on
form factor Y procedure for the
load
at the
(2)
Use the form and geometry factors found in (1) above to calculate bending
stress:
concentration
then and
distribution.
Table
apply
the
allowable
stress
Xlll
values
gives
formulas modification for
conditions. The factor Kv allows stiffness of rotating elements, load,
Table
XIII. -
given for
dynamic
reference
load,
factor
errors,
load factor
overshoot
presents
characteristics
values
of the
Table
XIV.
-
0.5
to 0.83
0.77
0.5 0.9 0.77 0.83
to to to to
0.77 0.91 0.83 0.91
0.77 1.1 1.3 1.0
for overload
driving
and
Overload Turbine
factor
driven
Ko that
factor
type
axial-flow
centrifugal
1.25
1.50
of stressing,
tooth
utilizing
as given
bending a plot
in figure
strength
of allowable
6.
58
for the operational
and
pumps
pumps
Velocity-compounded, 1 or 2 stages
by
and
Heavy-liquid
1.25
whether
inertia
Ko
1.00
quality
operating
i
account
Many stages
Determine gear
i
Factor Ko Related to Pump Type and Pumped Fluid
Many-stage gas and light-liquid
(3)
stress
elements.
Overload
Turbine
and
Recommended value
condition
Steady state Transient Shutdown
XIV
speed,
root stress
Kv
,
Table
size,
the
for
Dynamic Load Factor K,, for Various Operating Conditions
Range
Start Turbine
tooth
8
Kv for various
for tooth-geometry and tooth stiffness.
Dynamic
Operating
in
is adequate root
tensile
for stress
the
intended
vs number
life
and
of cycles
Modify the designasrequired to meet allowableroot bending stressvalues. Determine gear reliability by consulting figure 7, which gives the probability of tooth breakageduring 1 million cycles as a function of root bending stressfor four gradesof gear material quality. Considerproviding 20-percent excess load capacity to allow for future uprating of the turbopump drive system. Redesignthe gear mountings or gearsupport if the load distribution factor Km exceeds1.5. Specify shot peening of root fillets (sec. 3.4.5) as a means of improving tooth bending fatigue life if high reliability is required of highly loaded gears,or if fatigue life is lessthan that required. 3.1.7.2 The For the
TOOTH
FACE
gear shall
preliminary tooth
K are listed
not
design
pitting
index
in table
COMPRESSIVE be subject
to surface
purposes, K given
STRENGTH pitting
estimate
the
in equations
failure
due
compressive
(2a)
and
to compressive
strength
(2b).
of gear
Recommended
stress. teeth
limiting
XV.
Table
XV. - Preliminary
Design
Values
for Pitting
Index
K i
K value limits
Gear type Main power
Lubricant/Coolant Oil or fuel-additive b Propellant
Accessory
Oil or fuel-additive b Propellant
aThis
material
grade
is equivalent
adopted as an official designation bRP-I plus 2% Oronite 262.
to that
AGMA material grade 1 and 2
Material grade 3a or better
1000 200
2500 500
600 200
1000 500
used in aerospace
by AGMA.
59
gearing
but
has not
been
by
using
values
of
For preliminary turbopump gears For
detail
design,
compressive For design point value.
values
use
the
methods
compressive stress, use Sc K '/2 for gears with 20 ° PA.
of reference
stress at the pitchline and evaluation, use the pitchline
is more
Redesign
design estimates of with 25 ° PA; use 7100
the given
than
10 percent
gear
if the
in figure
greater
8 or if the
51)
or of reference
the stress
gear
surface
probability
at the
pitchline,
compressive
of failure
(fig.
When
compressive
reference
11
allowable
(table
compressive
5),
or
use
stress the
K '/2 for
steel
11 to calculate
is not
larger
of
known the
(as
design
increasing
for
following
use
exceeds
9) exceeds
can be reduced by widening the face, the addendum proportions (sec. 3.2.5).
allowable
then
stress
Compressive stresses diameter, or modifying the
6500
at the pinion's lowest point of single tooth contact. value; however, if the contact stress at the lowest
than
calculated
10 (p.
=
a new
values
as
the maximum
the
allowable
requirements. the
gear
material), an
estimate
pitch
consult of
the
stress:
s,u 1.8 or
Sty Sac
_I
1.5
where
Sac = allowable Stu = ultimate St y - yield
Initiate Deep
fatigue peening
compressive tensile
tensile
testing of gear
stress,
strength
strength
for turbopump gears, because increase in scoring tendency.
for lowest
for lowest
to establish contact
psi
values
surfaces limited
case hardness
case hardness
value,
value,
psi
psi
for Sac. to improve testing
60
compressive has
shown
strength that
this
is not practice
recommended can
cause
an
Recommended
case depths
Table
XVI.
-
to ensureadequate
Recommended Strength
compressive
Case
(20-Percent
strength
are shown
Depth
to Ensure
Adequate
Stock
Removal
Allowance)
in table
XVI.
Compressive
=
Pitch
Finished
Maximum
Case prior to finishing, in.
case depth, in.
grinding stock a
(one side), in.
20
0.012 to 0.020
0.015 to 0.024
0.003 to 0.005
15
0.015 to 0.025
0.018 to 0.030
0.003 to 0.005
12 to9
0.025 to 0.035
0.030 to 0.042
0.005 to 0.007
8
0.025 to 0.040
0.040 to 0.048
0.005 to 0.008
0.030 to 0.050
0.036 to 0.059
0.005 to 0.009 J
ause lowest possible values.
The the
effective depth
calculated
by
Effective Rc
case
to the
depth
lower
carburized
or nitrided
of maximum
methods
case depth
points
for
point
devised should
than
by
subsurface Buckingham
be considered
the
outer
turbopump
shear (ref.
the
depth
surface
power
stress.
39, p. 529) at which
case
hardness,
gears
Subsurface
should
shear
or Dudley
the hardness whichever
be twice
stress
(ref.
can be
10, p. 48).
is 50 Rc condition
or
is 10
is
more
demanding.
3.1.7.3
CHIPPING Tooth
Limit
case
tips shall depth
addendum, The
with
XVII;
chip
tip to twice
width
blended X refers
applied before carburization Y should be more generous corner tooth
buildup root
because
of excessive the
case
brittleness
depth
on the
or stress flank
(fig.
concentrations. 17) or to one-half
the
is greater.
tooth-tip
smoothly table
not
at the
whichever
minimum
Provide
RESISTANCE
is precluded.
should
tip,
end,
to end
and
be 0.25/P and
edge
and should for nitrided Avoid
edge
any
(ref. radii
radii,
have gears
2, ch. 5). (fig.
and
61
Y refers
gear
tooth
to tip radii.
surface roughness of 63/aim and should be applied before
discontinuities
areas.
18) on the
in radii
application,
in accordance
X radii
should
be
AA max.; X and nitriding so that particularly
in
I
I
0.Sa
-maximum
case
a_ addendum
i
Case
depth
at tip
Hardness
_i_
locations
tooth side for case depth
Core test
thickness
test
on
hardness location
Lower limit, working depth
Figure
17.
-
Sketch
showing
hardness
X
locations
for
radii
(tooth
ends
and
Y radii
Figure
18.
-
Sketch and
care
depth
and
tests.
illustrating end
radii.
62
gear-tooth
edges)
(tooth
tips)
tip,
edge,
Table
XVII.
- Recommended
Tip, End,
and Edge Radii
for Gear Teeth
Radius, in.
Hardening method
Y
Main-power gears
Accessory drive gears
0.015 to 0.025
0.010 to 0.020
20
40
10 to 12
0.010 to 0.020
0.005 to 0.010
20
40
16 to 20
0.005 to 0.010
0.003 to 0.008
20
40
6to 10
Max. possible 0.050
Max. possible 0.050
20
4O
12 to 20
Max. possible 0.030
Max. possible _< 0.030
20
4O
5to8
Nitriding
Lubrication
Deterioration life.
Lubricate
and
Recommended For
bearing
3.1.8.1
X
Pitch range
Carburizing
3.1.8
The
of gear
cool
the
lubrication
gear
range
and Cooling
tooth
gear
procedures
HEAT
that
surfaces
tooth
and practices,
by friction
surfaces
guidelines consult
with are
set
and
solid, forth
reference
wear
liquid, in sections
shall
or
gas
not
reduce
gear
coolants/lubricants.
3.1.8.1
through
3.1.8.4.
38.
REMOVAL
lubrication will not
system result
Provide sufficient lubricant well as from external sources coolant involved.
Surface roughness of radii, /_in. AA
shall
maintain
in degradation flow to balance such as turbine
the
gear
of material
system
within
a temperature
properties.
heat input from gear and bearing inefficiency heat soakback. Select the minimum flowrate
that will maintain an equilibrium temperature To achieve this objective, proceed as follows"
63
within
the
capabilities
of all materials
as of
(1)
Determine from
the
gears,
rate
at which
bearings,
and
heat
is to be removed
external
sources.
Assume
of 0.5 to 0.7 percent of the power transmitted reference 2 (ch. 15) or reference 12 for detailed loss. (2)
Add
any
heat
input
from
external
of specific
requirements)
and
summing
the
a gear efficiency
heat
sources
such
as turbine
allowed
(assume
determine
the
inputs
loss per mesh
in spur gear trains, methods of estimating
the gear case or heat radiation to the gear case. Select the maximum lubricant temperature absence
by
or consult gear power
gas leakage 210 °
maximum
inlet
into
F in
the
temperature
expected. (3)
Calculate above
by
specific Convert
the
lubricant
the
product
heat the
against
the
flowrate of
required
temperature
by
dividing
difference
the
found
heat
rate
found
in (2)
and
the
(assume it to be 0.42 Btu/lbm -° F in the absence value found into basic flowrate units and check following
in (1)
lubricant
of explicit the value
data). found
estimates:
Lubricant
type
Minimum flowrate, gal/min/hp/mesh
Oil
6.67x10
5.0xlO -4
Fuel-additive a
aRP-1
Ensure full
that
run
more
the
duration
at higher
Provide
lubricant over
viscosity circulated
3.1.8.2
if necessary
existing should
an associated
presented scoring
component
SCORING
a scoring
total
is adequate
environmental
because
the
to maintain
to maintain
temperature
fluid
viscosity
more
nearly
the
range.
required Most
flowrate
systems
for
will
flow
is lower. constant
flow
by eliminating
the
higher
not
(e.g.,
failure
of a shaft
seal).
PREVENTION tooth index
in descending risk and
supply
262.
at temperatures at the low end of the range. The quantity of lubricant be sufficient to ensure mission completion despite a single malfunction of
The contacting Maintain
the
temperature
heaters
plus 2% Oronite
system
-4
surfaces within order
as a design
shall not the of
experience
ranges
shown
preference.
limit.
64
PVT
destructive in table should
scoring.
XVIII. be
used
The
scoring
only
indexes
are
as a measure
of
TableXVIII.
- Recommended
Method X=
AGMA flash temperature c (ref. 14) PVT calculated at tooth tips (refs. 1 or 3)
s = surface bRP-1
When means
of Scoring
Index
Use
Recommended
Diester oils Fuel-additive b
1.5 min. 1.3 min.
Flash temperature index, °F
MIL-L-7808 oil Fuel-additive b
300 max. 350 max.
Contact pressure (psi) x sliding velocity (ft/sec) x distance from pitch line to point where contact pressure is calculated (in.)
For all turbopump gears
3.0xl
h/s a
value
0 6 max.
film thickness roughness
+ 2% Oronite
CCalculate At in. AA.
on Three Types
Scoring index
Bodensieck (ref. 13)
ah = lubricant
Limits
using
262.
surface
finish
factor
of 55/(55-s)
scoring risk is considered to reduce scoring: •
Reduce
lubricant
•
Increase
•
Use high lubricant
•
Redesign
•
Raise
gears
too
inlet
lubricant
flow
high,
(sec.
pressures to obtain
or
of 50/(50-s)
any
of the
in reference
following
larger
to 600
Reduce
overload
•
Modify
profile
radii
lubricant;
factors
• •
Increase Increase
•
Use finer
pitch.
•
Redesign
the
•
Lower
the pitchline
•
Lower
the
and
of curvature
roughness,
are recommended
as a
lead
gear system
see
table
Ko by reducing to compensate
to lower
VI.
(sec.
torque
(2 or more).
the
3.1.2).
65
loads.
by
using
EP (extreme
Use
only
extensively
sometimes
for elastic
velocity. velocity
of teeth.
of lubricant
number of gear reductions face width.
sliding
steps
s = surface
psi).
additives; these chemically active compounds storage, and this effect is not predictable. •
14, where
3.1.8.1). (60
properties
change
as shown
temperature.
scoring-preventing
additives
instead
peaks. deflections.
become
pressure) tested
corrosive
EP
during
•
Refine
•
AA. Increase
• •
Improve alignment if required. Select lubricant with higher viscosity.
• •
Redesign gears to have lower contact Use contact ratios larger than 1.4
3.1.8.3
the
surface
tooth
LUBRICANT
The
surface
but
do not
hardness
(60
reduce
the
minimum
roughness
below
6/ain.
Rc minimum).
stress.
PROPERTIES
lubricant
stability,
texture
shall
and
possess
acceptable
adequate viscosity
load-carrying over
the
capacity,
range
acceptable
of environmental
chemical
temperatures
of the application. Determine shown
lubricant in table
of lubricants. under
gear
Load
operating
lubricant, oxidizer
in with
case.
load-carrying
VI. Ryder values
Although lubricant avoiding
Alternatively,
Avoid
lubricants
with mixture
temperatures
down
use
of
dithiophosphate 3
percent
below
in most
high
gear
cases
guidelines,
to compare design
oxidizer
use the values
the relative
must
capabilities
be established
cannot
be allowed
by test
to mix with
its compatibility with turbine gas, fuel, or sludging that may occur if leakage enters the filter
volume.
viscosity
at
the
synthetic-base
involved.
elements
and
remove
accumulated
Avoid
lowest
operating
lubricant
is
MIL-L-6086
temperatures.
A
recommended
petroleum-base
when
lubricant
for
0 ° F. mixture
The
compound, by
a new
consider potential
MIL-L-7808
to -30 ° F are
RP-1.
or, as rough
be used
replaceable
excessively
a fuel-additive
using
testing
schedule.
or
at temperatures
by should
with
incorporate
service
fuel-additive
engines
achievable
conditions.
on a regular
The
capacity test results
selecting the a view toward
sludge
service
gear
as the
gear-system
recommended which
additive
should
Exercise
be mixed
caution
to
lubricant is
with
prevent
is recommended
Oronite the
fuel
moisture
262,
a
for
zinc
all
dialkyl
at a concentration
of 2 to
contamination
of
this
compound. Individual 6-month
production batches of intervals for retention
properties design
of this
is not
Select than
ambient
have
been
shown
synthetic-base load-carrying to be unstable.
oil should be retested capacity, because the Use
of this lubricant
at EP
for a new
recommended.
lubricants
fuel-additive (less
lubricant
MIL-L-25336 of specified
with
mixture 2 psia).
are
demonstrated
foaming
recommended
for resistance
MIL-L-6086
oil foams
extensively
pressure.
66
resistance.
MIL-L-7808
to foaming and
should
at low
be avoided
oils
and
ambient for service
the
pressure at low
With the exception of RP-1, propellants in general should not be used as gear coolants. Consider propellant cooling for applications with short life requirements, loads below 500 ppi, and speedsbelow 10 000 ft/min PLV. Testing should precede inclusion of propellant lubrication in final design. Use solid-film lubricants where loads, speeds,and intended life permit. For information on solid-film lubricants, consult reference40 and section2.1.8.3
3.1.8.4
LUBRICANT
The
lubricant
shall
weigh
Splashed-oil
delivery as little
and
less than
DELIVERY
Once-through
with
systems;base
Use
positive-displacement
the
temperature
range
of
lubricate
adequately
these
will
should
be
10 000 be
and reliably
and
for flow
lubrication will maintain
a constant-pressure
of withstanding
only
systems
of
pressures
short-duration
10-percent
excess
and
duty-cycle
systems
that
a more
pressurized
the
for gear
one-duty-cycle,
Provide
on maximum
pumps
used
ft/min.
used
lubricant.
for feeding
because
is capable
should
as the
reserve
pumps than
less than
flow
additive
calculated
range,
system
and
systems
velocity
drain)
temperature
lubrication
lubrication
pitchline
oil or fuel
such
shall cool
as possible.
(overboard
applications
wide
system
grease-packed
1O0 hp, with
SYSTEM
for
duration. must
constant
operate flowrate
system.
resulting
capacity
Ensure
over
a
over
a
that
from
low-temperature
total
weight
the
operation. Recirculating lubricant, tanks,
lubricant feed
lubricant,
lubricant
3.1.8.4.1
feed
or 60 percent Lubricant
gear tooth
surfaces.
lubricant radially
lubricant
penetrate
to the
toward pressure
pitchline
heat
when
exchanger
and system
is lower
controls
for
should
have
of the volume
the
flowing
than
the
total
a once-through a capacity
of
tanks,
weight
system. of
100
of The
percent
in 1 minute.
Nozzles shall
nozzles
inward
recommended
or pressurant, recirculating
nozzles
delivery
supply
and
(minimum)
Spray
delivery
directed
the
are
pumps,
pump
for
Lubricant
Place
systems
scavenger
reservoir
(preferred),
The
and
flow
on the
the
and
an adequate
disengaging
center
should
of gear
deliver
quantity
side
of
the
of lubricant
to the
mesh,
with
the
a jet
velocity
stream
of each gear. be
sufficient
pinion.
67
Methods
to
result
in
of calculating
the
required
that
will
velocity
are presentedin reference 21; a supply pressureof 400 to 600 psi is recommendedfor gears with PLV of 20 000 ft/min or greater. The nozzle spray should cover the entire face of both pinion and gear;a rule of thumb is to provide one nozzle for every 1/2 in. of gearface width. The minimum nozzle outlet orifice should be 0.015 in. in diameter to reduce clogging tendency. 3.1.8.4.2
Foaming
Foaming Excessive
of lubricant
foaming
should psia
minimum
3.1.9
by
which
selecting
with
gaseous
additives
to the
gear
alignment Make
Isolate
cooling
sometimes
low-foaming
nitrogen
or
occurs
at gear
lubricants, gaseous
by
case pressures
pressurizing
helium,
by
using
provide
rigid
below
the
gear
baffles,
or
2 psia, case to 5
by
adding
lubricant.
deflection deflections. of similar
envelope and
turbopump with
the gear
ensure
system for,gears
overall
compatible
gear case
adequate analyses When gear
forces,
calculating
gear
case)
to
determine
whether
pump
external
duct
structural
considering
all
utilize
Internal
and
thermal
strength
internal
the
forces
separating
loads
results
and
and
stress
loads
from
deflection
possible,
the
gear
distortion
by thermal
ducts
forces,
and
axial
in reference
should
analyses case
with
and
where
rigidity,
good
turbine
spacing
is
external
forces
loads
12).
be eliminated
if the
should
or mechanical
be
ducts made
when
as symmetrical
loads.
68
by the as
stress
and
temperature-induced actual
operation
loads
arising
from
helical
Gear-case
possible,
are supported
detailed
during
bearing
from
2 (ch.
and
taken
include
practical.
perform
of measurements
to be considered
are given
loads
be considered and kept as low as feasible (5 to 40 psig). and radial loads must be added when they are supported
External
mounting
distance.
gear-case
reactions
shall
bearings.
center from
(gear
layouts
possible,
cases.
tangential
the
not degrade
Gear Case
The
must axial
shall
of lubricant,
be prevented
antifoaming
To
of Lubricants
gears.
Methods
internal
pressure
Pump and turbine on the gear-case as they gear-case possible
must
of also
impeller structure.
be included
structure. to
gear
reduce
Whenever possible
in
Provide
clearance
tcmperatu,
es and
Fasteners are
and
required
for
bolts
should
installation gear-case Crack
of gear-case
with
sufficient halves
duct
brittle
and
fit.
a mininmnl
the
box,
Avoid
lacquer
application
of the
fasteners
full
deflections
bores
number
due
to
of special
tools
assembly,
and
turbopump
inside
the
gear
applied
load
required
components bearing
gear
(stress-coat)
will indicate
Locate
so that of
system.
of gear-case
press
clamping tinder
joint. Use O-rings whenever possible. the
due to failure case.
force
loads.
or other
effects
of
of seals)
GEAR
will
to gear
reveal
design
case.
the
case
outside
magnitude
and
modification.
by use
of locating
pins
by line
boring
assembled
the
or dowels
with
gear
case
with
Clamp recessed
screws
the gear-case seals (not
malfunctions
so that
some
of
or bolts
gaskets)
of
prevent
relative
movement
together
with
a metal-to-metal
to prevent
associated
redundancy
to
components
leakage
components
or margin
from
(e.g.,
of safety
parting
planes
overpressurization
is designed
into
the gear
DETAIL
Pressure Angle
The pressure A 25 ° pressure gears,
Consider
pins installed.
Provide
3.2.1
volutes.
accessible,
engine
during
relocation
gear-case
3.2
and
disasselnbly
using
strains
or slight
Anticipate
in the
pattern
accurate locating
and
strength
direction
line-to-line
manifolds,
be made
assembly
surfaces.
Obtain
ducts,
pressures.
for
turbopump Test
for
angle angle
particularly
3.2.2
The
of the gear shall is recommended
if long-addendum
not
detract
from
in preference ,pinion
teeth
on a gear shall
satisfy
the
tooth
to lower
are used
load capacity.
values
(see sec.
for
turbopump
power
3.2.5.3).
Number of Teeth
mtmber
opera tioHal Choose the constraints:
of teeth
or mamtfacturing
number
of teeth
the
gear speed
ratio,
yet
not
result
in
difficulties. required
to
achieve
69
the
specified
ratio
within
the
following
11) Select gear pitch that provides adequatestrength: if bending (2)
strength
by using
Avoid undercutting that the number
coarser
pitch
and
therefore
pinion teeth by adjusting of teeth does not fall below
necessary,
fewer
increase
tooth
teeth.
pinion pitch the lninimum
and pitch diameter so given in the following
chart:
Power gears, minimum teeth
Accessory gears, minimum teeth
20
26
22
22.5
23
19
25
20
16
Pressure angle, deg
(3)
Establish with
(4)
the
Ensure teeth
(5)
number
the natural
hunting-tooth in meshing
Limit
the
Contact
The
The at
ratio, greater
3.2.4
meshing
maximum
there
number
of
costs
are likely
frequency
or any wear
life
are no common teeth
to
100;
does
not
coincide
of its elements. by
choosing
numbers
of
factors. otherwise,
manufacturing
and
to be excessive.
tooth
loads
to
successive
teeth
shall
not
produce
excessive
loads.
contact gears
and
so that
of
a value
loaded
action
tooth
gear system
Ratio
transJer
dynamic
gears
so that
of the
maximum
quality-control
3.2.3
of teeth
frequencies
calculated than
because
1.2.
of the
with
the
formula
Use
1.5
when
inherently
given
in reference
possible.
low
contact
not
result
Avoid
10 (p. 55),
stub-tooth
should
designs
for
be kept highly
ratio.
Face Width
The
width
o.[ the gear .[ace
shall
in uneven
load distribution
across
the
./ace. Keep helical
the
ratio
gears,
of face the
total
width width
to pitch for both
diameter helicals
(F/D) should
7O
less than not
exceed
1"1 for spur twice
the
gears. pitch
On
double
diameter.
The following effective valuesfor F/D arerecommendedfor turboptunp pinions: EffectiveF/D values Preferred maximum Limit
Geartype
3.2.5
Tooth
Tooth the
gear
and
in reference
(sec.
3.2.5.5)
3.2.5.1 The
full-depth
Accessory-drive special
design
Helical
0.60
0.9
Doublehelical
1.1
2.0
proportion 26
whole
0.7
shall
for
as required
prevent Use
tooth
WHOLE
0.5
Proportions
proportions
Use
Spur
fine
ensure
maximum
system pitch
listed
(Pd
to obtain
strength
and smooth
in reference
>_--20)
involute
the maximum
25 gears.
load
tooth
for
coarse
Include
action. pitch
profile
(Pd
_
19.99)
modifications
capacities.
DEPTH depth
shall
use of adequate standard gear goals
tooth designs
exisL
not
sacrifice
fillet
radii.
form should
use the
strength,
proportions follow
following
make
as listed
manufacturing
in reference
the standard
proportions.
whole-depth
values:
Gear type
25 whenever For gear
Whole depth 2.35
Main-power-train gears with adjusted addendum and dedendum
2.40 tO
Pd
Pd
2.25 Moderately gears
difficult,
2.35 tO
loaded accessory Pd
-Pd
2.25 (standard)
Lightly loaded accessory Pd
gears
71
or
possible.
designs
where
Stub
teeth
used
for
(those
in which
accessory
and
the
gears,
sharp transfer of loads. Stub additional tooth tip clearance.
3.2.5.2
TOOTH
Tooth
teeth
working
because can
thickness
backlash
2 (ch.
5, p. 5-20)
be used
by
values
shall
thinning
the
for design
not
reduce
3.2.5.3.2
gear
tooth
procedures
proportions
shall
values
proportions
of addendum
equal-strength with
teeth
of the
increase
the
gear.
For
driven must
be made
A) and
3.2.5.3.3
obtain
shown
not
rather
cause
than
teeth
in internal-gear
the pinion
in selecting
undercutting tooth 3.
in equal
in figure
not be restllt
design
tooth.
tooth
ill
to give
Consult
reference
thickness.
of teeth. undercut.
whole
addendum gears
in pinion
depth
Proper
values
for
spur
and
from
similar sheet
strength.
gears
with
20 ° pressure
and
gear.
Figure
11 also
pinion
and
equally
decrease
for which
figure
angle
to obtain
can be used
for
is used.
of the driving
different
to generate
bending
11 for spur
Y factor)
same
25 (information
those
charts.
Calculation
the
11 is valid,
methods
are given
addendum layouts
in references
and 8
B).
Equal Sliding Velocities
Addendum
figure
) should
strength.
to be used
shall result
(balanced
25 ° PA if the
In general,
To
of stub
Equal Strength
Addendum
(App.
2.00/Pd
ratios
to advantage
tooth
Use the required pinion addendum to avoid helical gears are shown in figure 1 of reference
tests
is less than
contact
Undercutting
Addendum
gears
low
ADDENDA
3.2.5.3.1
Use
depth
the
THICKNESS
Obtain
3.2.5.3
theoretical
power
equal
proportions sliding
2 of reference
shall
velocities
3 (for
result above
in minimum and
20 ° PA) or figure
below
sliding the
pitch
3 of reference
72
velocities. line, 3 (for
choose 25 ° PA).
addenda
shown
in
In summary, which
establish
are listed (1)
No pinion
(2)
Root
(3)
Sliding
(4)
Peak
When
untried
3.2.5.4
the
fillet
velocities
addenda
radii
of addenda
oll the
basis
of the
following
factors,
of importance:
maximized
compressive
ROOT
values
order
undercutting
strength
by equalizing
minimized stress
pinion
by adjusting
and
radii
gear
strength
of curvature
minimized.
proportions
are used,
confirm
design
adequacy
by gear
tests.
FILLET
Gear-tooth-root Root
design
in descending
fillet should
radii shall
be maximized
for fillet radii for 25 ° PA aerospace be calculated as shown in reference
not
result
in excessive
to minimize
root
gears are shown 25 (information
stress
bending
concentrations. stress.
Recommended
in figure 19. Limiting sheet B).
radius
values values
0.37
\
For
gears
with
value ÷ P pitches, use
other
chart
%
O. 34
o" 0.33
.. _o ,0.3o
_o._
<,, _
,,
0.29
k
0.28 17
20
24
30
40
Number
60
80
of Teeth
Figure 19. - Recommended root fillet radii vs number of teeth (25 ° PA spur gears).
73
125
.o
may
A large-scale the
root
The
gear
the
(20×
fillet
3.2.5.5
and
grinding
tool
design
limits.
Involute
Tooth Modify
bending
1000
the ppi
profile
be
used
for
27 to calculate
3.2.5.5.2
Tip Relief
allow
for
of active profile
tooth
for
only
relief
3.2.5.5.3
When
the
be made
to ensure
that
tip.
review
not adversely at face
the
chosen
this
and
affect
loads
estimated
13(a))
radii
to ensure
ppi
deflection
drive
action.
deflection
of tip and
accessory
tooth
of 2000
a tip bending
(fig. required
not
the
interfere
errors,
gears
above.
of 0.00035 exceeds
root.
gears.
and
0.0005
Tip-only Employ
in. per in.,
modification the
methods
of
modification.
that
at start
provide
a tip relief
will
operate
to zero
at the
profile
contact
of rnesh.
at
speeds
25 percent
modification.
ratio
does
not
of 0.0005 exceeding of active
Recalculate drop
in. for the
below
15 000 profile
contact
first
25 percent
ft/min
depth ratio
PLV.
point
of gears
The
if speed after
tip
1.2.
Lead Modification deflection
the
teeth
0.0005
in.
is recommended
end
should
tooth
for Speed Effects
Crown
Gears
shall
assuming
power
in detail
requiring
that
Gear tooth concentration.
lead
gears.
can drop
factor
to ensure
profile gear
should
operating
by
loaded
manufacturing
profile
gears
modification
tips shall
modification
is the
steel
profile
reference
To
loaded of all gears
on lightly
The gear
manufacturer
modification
load
"barrelled"
tooth
mating
for Load
of highly
required
face
consider
the
MODIFICATION
Modification
the involute
Estimate
of the gear with
of cutter
TOOTH-FORM
3.2.5.5.1
layout
will not interfere
cutting
feasibility
may
minimum)
radii
chart
for a properly
supported easing
of gears
in rigid
as shown
or
that
misalignment
may
for
be subjected
highly
crowned
gear
gear
cases,
in figure
13(c)
shall
loaded
not
result
to misalignment. gears.
See
figure
in
excessive
Crowning 13(b)
for
stress
of 0.13002 an example
to of a
tooth.
while
not
to prevent
74
requiring stress
crowning,
concentrations
should
be provided
at the ends
of the
with teeth.
For gearswith F/D values greater than 0.5 or with face widths over 1 in., consider helix correction to compensatefor torsional windup of the geartooth. A preliminary estimate of the required helix correction is 0.0002 in./in, of face width. Lead modification values recommendedherein should be used as preliminary designvalues in the absence of testing experience. For a more detailed calculation of theoretically required modifications, consult references41 or 42. Normally, lead corrections should be limited to 0.0006 in. maximum to avoid contact stress increaseand reduction in load capacity. Test for lead modification required to compensate for misalignment by coating the teeth with flash copperplate, operating the gear mesh briefly under reduced load, and studying the contact pattern created.Repeat this test after applying profile modification to confirm its adequacy. This procedure is especially important for bevel gears;however, to determine proper lead modification for the torsional windup, the gearsmust be run under full load. The effects of torsional windup may be reduced by driving through splinesaxially located at the center of the gear face (e.g., the pinion shown in fig. 4).
3.2.5.6
SURFACE
The
shape
contact The
rate
TOLERANCES of
the
active
involute
or lead
of reversal
is acceptable
should
for
accessory
by examining
not
exceed
,
drive
the traces
l/ -
shall
not
result
in high
local
stress. 0.0002
involute or lead profiles for 8- to 12-pitch must not be concave (fig. 20). A dimension reversal
surface
and
/
any
25-percent
portion
and
loaded lead
power
gears.
Determine
/
I :llllll l (b)
Acceptable
Figure
20.
-
Acceptable
and
75
the
charts.
f/i:
/
///ill (a)
of the
active
power gears. In addition, the overall lead pattern of 0.0003 in. per 25 percent of the active profile
lightly
on involute
in. for
unacceptable
Unacceptable
lead traces.
(concave)
l
rate
of
3.2.5.7
SURFACE
3.2.5.7.1
Contacting
The
surface
resistance
Grinding
score
texture and
surface
should
not
Surfaces
of
fatigue
not Do
not
only
are
than
as the
texture
exceed strive more
in #in.
for
surface
with
Table
Surface
contact
final
the
50
directions
roughness
XIX.
-
values
Recommended
max.
Power gears, PLV < 25 000 ft/min
6
20
Power gears, PLV > 25 000 ft/min
6
16
Accessory
6
40
Noncontacting Roots
drive gears surfaces
not
for
illustrated
in
values values but
for less
adversely
Values
tooth
affect
than
scoring
12.
6/.tin.
AA
for Gear
Peak-to-valley
and
AA,
are because
such
greater
20
AA.
#in.
waviness
shown
to have
Surface
machining
profiles.
roughness
appear
6 #in.
Preferred
contacting
figure
surface
actually
between
Surface roughness, _in. AA
surfaces
shall
method
to manufacture
roughness
min.
Contacting
surfaces
finishing
Recommended
expensive
surfaces
tooth
life.
is recommended
Measure
XIX.
TEXTURE
operation
Grinding
Very
(I) Hobbing
Very critical
(2) Shaping (3) Grinding
critical
(do not grind
after case hardening) Mounting
surfaces
32
Grinding,
turning
Critical
Rims and webs
125
Crush grinding
or turning
Important
Hubs
125
Crush grinding
or turning
Important
Lands and tips
125
Minimal
76
tendency
Importance of surface condition
max.
64 100
surfaces
Roughness
and Fillets:
Before peening After peening
in table
to
A light glass
vapor beads
texture
blast
or peening
requirements
program
that
3.2.5.7.2
compares
stresses,
XIX
presents
shall
3.2.6
Rim and Web
3.2.6.1
RIM AND
residual
webs
minimum
weight
Web
thickness
should
0.20
in.,
the
are
fraction Avoid
of the
root
contain
area
shot
be determined
surface
or
Surface by
a test
textures.
harmful
expensive
stress
concentrations
or
to manufacture.
roughness
values
and
production
finishing
must
not
be permitted
because
this process
will
stresses.
lowest
gears
be less
the
shall
carry
the
required
load and
shall
be of
are between
0.10
cost. than
same
size
lightening-hole
0.10
in. When
as the
face
face
and
proportions
and
web
web
proportions
XX;
dimensions
rims
stock shot
and
in table tooth
bolted
sufficient
tensile
not
surface
tensile
never webs
rim
shown
inaccuracy
Specify
should
different
small-size
performance.
widths
utilize
for lightly
lightening
loaded
power
and
holes
to reduce
gears
are shown
21.
Recommended PLV)
shall
on power
and
Recommended
in figure
blasting
with
with
WEB PROPORTIONS
and
make
of gears
not be excessively
in the
undesirable
weight.
after
surface lubrication
gear surfaces.
carburizing
rims
contacting
borderline
gear
recommended
produce
The
finished
surfaces
yet
for nonactive after
tooth
Surfaces gear
residual
Grinding
the
gear
improving
performances
Noncontacting
methods
for
for
Noncontacting
Table
of the
is recommended
whole and
fretting
stress,
webs, at
for weight peening
depth
or on gears
from
to figure
experience 14 and
(up are
to 25 000
presented
ft/min
as a decimal
h t.
because the
removal
of gear
derived refer
rims that
bolted
joint joint.
as shown and
deflection If
balancing
in figure
webs
are subject
77
of
undesirable gears
gear
is required,
meshing provide
22.
on main-power to web
causes
fatigue
gears failures.
or other
gears
with
high
\\
Avoid
extension
of lightening hole into web fillet radius
0.7dto d
Figure
21.
-Sketches design
illustrating of
lightening
78
recommendations holes.
for
Table
XX.
-
Recommended Number
Item
Rim
and
Web Thicknesses
of Web-Lightening
Main power
Cryogenic
and
Holes
and moderate
Light power gears
power accessory Rim thickness*
1
1
0.7
Web thickness*
1
0.7
0.5
Number
*Thickness
of lightening
in inches
whole
None
holes
= factor
shown
times
tooth
Odd numbers
whole
5, 7, 9, etc.
depth.
depth
Minimm
thickness
rim
= ht ebia_kremg ved
te_;emovedfor
(b) Alternate (a) Typical
Odd numbers 5,7, 9 or even numbers >6
rim
rim
configuration
configuration
Figure 22. - Recommended locations for stock removal for balancing.
79
3.2.6.2
GEAR
RESONANCE
The gear The
shall
frequency
part
of
3.2.2). factors.
of gear tooth system.
Hunting-tooth of lightening
the
and
natural
resonant
precise
frequencies,
Campbell
diagrams
per second
Avoid
designing
expected
and
the
Provide
case.
or other
components
rather gears
of the gears
3.2.7
Tolerances
Use
the
table that
For
VII. the
Finer
designer
critical
to
if the calculated
spur
gears
yet
shall
that
power
tolerances
its torsional
gear range
from
frequency
by accelerometers
a few
to
are discovered.
forces
balancing
is in the attached
amplitudes
imbalance
to include
to establish
frequency. natural
if destructive
plan
sensors
are detrimental
provisions
on other
gears.
for
tolerances
must
or shaft
for low
piezoelectric
should
mesh
be detected
be initiated
gears
for reduction
specified
coarsest
application.
on the
and reliability,
may
in reference
is recommended
for each
investigated
that
modal
frequencies.
operating
such
If possible,
in preference
are recommended
capacity
should
components. than
Frequencies
The
are adequate
and
be constructed
maximum
system
testing
(sec.
common
or test.
methods salt)
gear meshing
Resonances
action
Dampers
Tolerances
shaft
sand-pattern
contain
as outlined
however,
of any
vibrations
not
calculation
be calculated
(popcorn
should
modes. of the
range.
Corrective
for balancing
helical
and
speed
to bearings
Use
gear
and
salt
diagrams)
resonant
can
by
should
range.
frequency
reinforcing
gears
accurate;
for determining
to 150 percent
operating
gear
tables
table
to avoid
design
gears
Shake
to a resonant
of mating
gear
reasonably
(interference
frequencies
cycles
new
in the gear operating
correspond
is desirable
are
fine-grained are required
not
of rimmed
frequencies
resonances
in webs
of any
determination.
(accelerometers)
action
frequencies
but
should
holes
frequency
calculated
or lateral
meshings
number
for more
the
torsional
the
23. These
forcing
have
The
Determine shapes
not
will
gears,
will require
coordinate
and
when
vibrational
of vibrational
response
shaft not
be
precise
exceed
the
use AGMA development
8O
enough
to
capacity
quality on
by actual
levels
and
are
anticipated.
rims (ref.
achieve
the manufacturer's
satisfy
evaluate
problems in gear
21).
good
life
requirements
9 to 13 or the values
the
part
gear
test.
load
.capabilities.
of the
gear
of given
manufacturer
the in
3.3
MATERIALS
3.3.1
Gears
The properties Material
recommendations
are
are
in
considerations properties tests
of the gear material
presented
by invoking
as necessary
Materials
used
uniformity
in
over
Recommended protection
(1)
Cover
the
be provided gear
Maintain
Plate
require ground
surfaces
is not
0.0003
during
new
and
Ensure
specifications
be
work
specific
material
consistent
material
and
purchased
in
be performed
the
not
quality
mill
cleanliness,
on
lots
control
to
ensure
a main-power
hardenability,
gear
and
carbon
lubricated
with
with
for
per
MIL-P-27401
or
per
QQ-C-320
plate
is preferred
an accurate,
hard
surface.
to the
required
recommended.
to 0.0005
For
in. on
gears
for
Tbe size.
the
corrosion
or areas
plating
enclosed
gears
such
as
per
electroless
nickel
per
as locating should
plating
in cases,
idle
helium
thickness
plating,
throughout
gaseous
such
Chromium
nickel
compounds
fuel-additive.
atmosphere
Chromium back
preservative
oil and
protective
chromium
therefore,
means:
periods
nitrogen
with
corrosion-resistant;
following
idle
inert-gas
gaseous
exposed
lubricants
are
for systems
surfaces
surfaces Dry-film
XXI,
3.3.1.2.
should
will meet
by one of the
continuous
oversize, are
and
or machining
material
surfaces
MIL-C-26074. which
table
or establish
materials
periods with MIL-P-27407. (3)
3.3.1.1
requirements.
for the gear.
MIL-C-16173
(2)
in
gears
forging
power-gear must
design
run of gears.
no
that
requirements
sections
standards,
a production
it is established
content
summarized
turbopump
that
satisfy
consistency.
critical
It is recommended until
existing
to achieve
shall
surfaces, be 0.002
of active
gear
recommended or 0.0009
in.
tooth
thicknesses
to 0.0011
in. on
to the atmosphere.
(sec.
2.1.8.3
and
ref.
with
propellants
40)
can
offer
a
low-cost
means
of corrosion
protection. Lubrication is contemplated, should
of power
gears
consult
be an integral
part
section
2.3.1
of any gear
alone
for materials design
project
81
is not that
recommended; have
involving
been
used.
if however, Testing
propellant-lubricated
such
use
of materials gears.
Table
XXI.
-
Recommended
Materials
and
Material
Requirements
Item
Material
quality
Intended
use
grade
AGMA 1
AGMA 2
Accessories
(alloy designation)
Medium
power
Main-power
4a Very critical gears
train
AMS 6265
AMS 6265 b
AMS 6265 b
9315 3310
AMS 6260
6260 b
AISI 9310 b
AISI9310 9315
AISI 9310 b
8620 4620
4340 percent
Core Hardness, Case
3a
AISI 9310
8620 4620
oo
Gears
Recommendation
Material
Carbon content, Case
for Turbopump
Rockwell
Per material
specification
0.75 to 1.00
Per material
specification
Per material
specification
0.75 to 0.95
0.8 to 0.95
0.10 to 0.13
0.11
to 0.14
"C" scale 58 minimum
58 to 63
60 to 63
61 to 64
31 to 44 No
32 to 42 Optional
34 to 42 Yes
38 to 42 Yes
No
Rarely
Yes
Yes
No
Optional
Yes
Yes - special requirements
Loose
Adequate case
Grain size (per ASTM E t 12-63)
3 to 5
5 minimum
Carbide network
SrrmU continuous allowabIe
Core Size effect considered Material
purchased
in registered
Cleanliness
requirements
Case depth
control
Retained
austenite,
(a) Determined
mill lots
specified
percent
noted,
bsp_cial
not
currently
hardenability
an and
Networks required noncontinuous
Adequate to ensure unitbrm case
thick,
6 minimum to be
No significant allowable
Adequate to ensure uniform case
AGMA-designated procurement
grade.
requirements.
thick,
7 minimum networks
No significant allowable
maximum
by visual examination
under magnification (b) Determined by X-ray diffraction
aAs
networks
to ensure uniform
15
10
5
3
25
15
15
13
networks
3.3.1.1
IViATERIALGRADES
The quality Gear
materials
The general recognized
of gear nzaterials must
be graded
requirements by AGMA
shall
meet
to achieve
the specified the
design
performance
requirements.
required
for turbopump
service.
for the grades are listed in table XXI. Grades 1 and 2 are presently (ref. 3) for aircraft quality gears. A new designation, grade 3, is
recommended for most turbopump mainpower gears; for even more critical applications, a potential grade 4 is listed. Uprating and increasing performance requirements require an upgrading of the gear quality, but cost and schedule considerations require that the designer specify the lowest grade that will meet the requirements of the design. AMS 6265, a vacuum-melted aerospace gearing. Allowable
AISI 9310 carburizing steel, is recommended for most bending and compressive stress levels are given in section 2.1.7.
H-bands should be specified for critical gears to control the material hardenability. For the same reason, the carbon content should be specified to tighter limits than standard (table XXI). Reference 43 (pp. 189-216) presents the important aspects of hardenability of steels.
3.3.1.2
METALLURGICAL
The metallurgical design. Specify the requirements for carburized
PROPERTIES properties
of the
hardness requirements on on the gear forging drawing. steels in the various grades Table
XXII.
-
Recommended
materials
shall
meet
the
requirements
of
the
the gear drawings; specify the hardenability The recommended case and core hardness ranges are shown in table XXII; the higher values of case Hardness
Values
for Carburized
Gears
Hardness AGMA grade 1
AGMA grade 2
Grade 3 a
Grade 4 a
89.2 min.
89.2 to 91.5
90.2 to 91.5
90.5 to 91.7
58 min.
58 to 63
60 to 63
61 to 64
D = 0 to 6 in.
31 to 44
32 to 42
36 to 42
38 to 42
D=I
31 to 44
32 to 42
34 to 42
36 to 42
Use
Case (Rockwell
15N superficial
hardness) Case b (Rockwell Core (Rockwell
C) C)
to 12in.
aAs noted, not currently an AGMA-designated bMeasure with 15N scale on profile of gears
grade. to be placed
in service.
83
hardnessshown in tile table are more desirablethan valuesat the low end of the acceptable band. It is recommended that, when contact stress is critical, the acceptable band of hardnessbe narrowed by raising the lower limit to the value of the next higher grade. Grade 3 is recommended of Grade
for most
3 gears
is shown
turbopump in table
Table
power
gears;
detailed
recommendations
for hardness
XXIII.
XXIII.
-
Recommended Material Grade
Hardness 3 a Gears
for
(Carburized)
Case Equivalent D, in.
Core R c
Rc
15N
0 to 4
36 to 42
60 min.
90 min.
4 to 8
34 to 42
60 min.
90 min.
8 to 12
32 to 42
60 min.
90 min.
aAs noted,
No and
continuous
carbide
discontinuous
metallographic Carbide
appear sizes
amount
undesirable
as the
15 percent
retained
3.3.2
be
gear
500
may
(table
to
times
in. are
austenite,
material
austenite
be allowed,
beneficial
to 0.0003
retained
an AGMA-designated
although the
total
become
carbide
performance
too
The
case
absence brittle.
networks of
is recommended
acceptable.
but
grade.
of
that
turbopump
are
fine
gears.
A
for evaluation
of-carbides.
structure
not
retained
Turbopump
must austenite
gears
have
an
could
should
have
be 5 to
XXI).
Gear Case
Gear-case lubricants Cast
to
may
magnified
up
of
currently
networks
specimen
particle
excessive
not
materials used
aluminum
applications. corrosive
materials.
be
chemically
and structurally
alloys Cast
shall
suitable
A356-T61,
The
specific
steels alloy
nature
must
with
for supporting
A357-T61,
corrosion-resistant
the highly reactive chemical contact with oxidizers.
compatible
and
should
Tens-50
be used
be compatible
of magnesium
84
the
alloys,
the
are with
and
loads.
when these
coolants
recommended the
gear
for
case may
the
propellant.
alloys
should
most
contact
Because not
be used
of in
Table
XXIV
Reconunended
Processes
and
Process
Controls
for
Fabricating
Turbopump
Gears
Recorumendation
Process
or Control
Accessories
F.rging
Use
of
Medium
forging
optional
Open
power
or closed
MAin-power
die
forging
required
Testing
and
fl)rging
source
train
qualification
Very
of
die
and
required
Forgings
critical
with
gears
integral
qualification
of die
teeth and
recommended
forging
source
re-
quired
('uuer
control
Finishing
No
method
for
profile
Only
Grind,
surfaces
hone,
lap
or
Grind
shave
Rot)t
Ireatment
after
carburization
on
burn
Detection
acceptability
Grinding
allowed
Light
method
Stock
remowll
burns
accepted
Small
percent
of run
radii
c,.m::rol
critical
Grind
required
cutters
Grind
required
are
registered
(new
methods
may
be
re-
not
but
recommend-
No
grinding
permitted
No
grinding
pernritted
allowed
None
accepted
None
Nital
etch
Mild
accepted
nital
None
etch
accepted
Mild
nital
etch
a
percent
of
run
in-
100%
of
run
inspected
100%
of
run
inspected
Small
percent
of
run
in-
100%
of
run
inspected
100%
of
run
inspected
spected
percent
of
run
Large
inspected
Shot
on
Yes
quired)
Large
inspected
Fillet
required
Grinding
Visual
control
Yes
gears
gears
ed,
(.;rinding
critical
spected
peening Roots
Special
Rims
No
Special
Webs
No
No
Heat-treatment
cases
only
IX
Pit,
brick-lined,
or
Processing
2X
tO 4X
4X
minimum
2X
to 4)(
4X
minimum
2X
to 411
4X
minimum
control
Magnetic
particle
Analysis
of type for
or vacuum
Stainless
or infrared
Prefer
teeel
or vacuum
retort
Vacuum
retort
Infrared
gas
Dew
point
or
car-
Dew
pack
point
gas
infrared
gas
analyzer
inspection
Yes
Yes
Yes
Yes
Optional
Optional
Yes
Yes
carbon
content
melhod
for
carbide
Randonr
sample
examination
determination
Examination
visual
ot" micro-
structure
under
nification; optional
type
at
microstructure
mag-
type
analyzer
only
analyzer
Ib
heat-treat
only
retort
burizing
network
only
Brick-lined
better
Inspection
cases
furnace
Type
sample
intensity
heat-treat
500X of
of
type
2
sample
Examination treat
at 500X
sample
quired,
type
type
of heat-
2 or,
when
level
on
Examination re-
sample
at
type
IO00X
of heat-treat
3
30
I or 2c
sample
Retained
austenite
determin-
Random
ation
check
microstructure amination ray
htspection
of all
gear
dimensions
or
by
Microstructure
examin-
Determination
ex-
ation
diffraction
gears
X-
on
or X-ray large
enlbrittlement
relief
required;
Sampling
Required
bake
sample
is a rod
C]leaHreal dlleat-lreal
sample salnple
is f[Olll Ihe S[llllC nlaterial ao.,t has the Sallle is a sectitm cut fronl :in actual gear.
of inspection
equipment
lllateri.,5
or
on
large
per-
X-ray
Required
of gears
at 325 ° F for 2 hrs.
blleal-treat
e Fraccability
of tile same
of run
of
microstructure
100%
examination
diffraction
of
Determination by
of
nricrostructure
X-ray
level
on
100%
examination
that
accompanies
the cross
gear
section
through
its heat-treatnlenl
cycle.
as tile gear.
Io standards.
85
on
10092,
of gears
e
Required
diffraction
on
100%
of gears
of and
diffraction
cent
allydrogen
percent
by
e
gears
Preparatory to selecting the material for the gear case, consider the effect on the gear alignment, clearances,and backlashof the relative gearand gear-casedeflections asgoverned by the elastic modulus andthermal expansion coefficient of the intended gear-casematerial. Determine the resulting changes in center distance and backlash, and choose another .materialif the results aredetrimental to gearoperation or gearlife.
3.4
FABRICATION Gear
fabrication
limit
gear life.
The recommended table XXIV and
3.4.1
and
process
fabrication techniques, in sections 3.4.1 through
controls
processes, 3.4.5 that
shall
minimize
and process follow.
conditions
controls
that
are summarized
in
Forging
Material Forgings Either should
processes
grain
should
orientation
be used
shall follow
to produce
approximately
gear blanks
bar stock or forgings may be used be used for grade 2 gears. Accurate
the finished
for all turbopump
gear outline.
power
train
gears.
for accessory gears. Open- or closed-die forgings closed-die forgings are needed for grade 3 gears.
High-energy-rate forgings of gear bodies complete with forged teeth are preferred for grade 4. All main-power gears for turbopumps should be grade 3 or better and should be made from forging blanks in which the direction of grain flow is controlled. These forgings Should contain no laps, voids, or banding. The forging supplier and the dies used should be qualified and figure
approved.
The
grain
flow
required
in the
cross
section
of a typical
forging
23.
q_
Center
line of finished
I
Grain
flow
Figure 23. - Cross-section
sketch of a forging
grain flow.
86
showing
proper
gear
is shown
in
3.4.2
Tooth The
tooth
without Hobbing clearance
cutting
reducing
is the must
components required
gears.
Green finish.
20 pitch
method
shall
gear load
capacity.
axial
undercut,
and
grinding Gears
Should
space
finer
20 pitch
before
should
3.4.3
be allowed
Use
stock
be used
than
be precut
is limited.
grinding
should
more complete discussion of manufacturer must coordinate time
satisfy
the
gear
configuration
preferred cutting method because it produces exist for the cutter. Shaping should be used
where
radii, root
Cutting
short-pitch
at the form
for
hobs
can be ground
to
diameter
work-hardening
gear grinding.
a good to cut
from
and
testing
an uncut
optimum
fillet
turbopump
gears
10 (chapters
and
axial other
for obtaining
blank;
reference
of cutters
obtain
and
tooth cutting and tool desagn. The and approve the tool form and cutter
for procurement
finish; however, gear teeth near
for specialized
metals
Consult
requirements
a good
coarser 5 and
than
6) for a
gear designer and the design. Sufficient lead
grinding
forms.
Heat Treatment
The
heat
without The
gear
any
machining
treatment inducing
blank,
of
gears
shall
produce
the
material
properties
required
defects.
whether
bar
or forging,
should
be normalized
at 1700 ° to
1750 ° F before
is started.
The
proper
material
properties
after
tooth
cutting.
Areas
listed
where
in section
hardening
3.3.1.2 is not
should
desired
be obtained should
be
by
masked
carburizing by
copper
plating. The
pack-type
carburizing
furnace furnace with on carburized
dew-point-control, 3 if control
and
pit-type timing
recommended
for
carburizing
infrared
analyzer
potential gradient For
critical
at the and
to gears,
for end
most
control. of the
minimize choose
Duplex cycle retained
only
is
not
recommended
an infrared samples
gears
and
a gear manufacturer
87
gear
stainless-steel
processes
be employed
austenite
any
grade.
A
gas control may be used through grade is very strict. The type of furnace
is a vacuum-retort
carburizing
should
for
that
reduce
to obtain
carbide
the
networks
experienced
type
the
desired near
in carburizing
the
with
an
furnace
carbon
carbon
content
outer
surface.
procedures.
3.4.4
Tooth
Finishing capacity. The
operations
copper
where
Finishing
place
that
is used
it is unwanted
introduces
the
The
tolerances
close
hardening, process
after
to mask
should
potential
be
of
loaded
for
accessory
Highly loaded accessory area after hardening.
may
zones. honing
Zone A, the if allowed)
active should
and
thus
grinding
prevent not
usually
require
profiles from
this
the
not
reduce
gear
carburization involving
in the
acid,
be ground
pattern
tooth.
a finishing
hardening
distortion.
areas
because
acid
in the root
for an external
velocity should
should
gear.
The
after
Grinding
honing
may
is the
be
,oed
on
is below 20 000 ft/min. not be etched to obtain
to maintain
gears
operation
process.
Abrasive
main-power-train
profile, is the be performed.
tip of the
shall
a process
risk is low and if the pitchline for turbopump gears. Teeth
and
the
the
gear
correcting
gears
15 illustrates
toward
by
resulting
gears
Figure
diameter
gear
on
accessory gears if the scoring Lapping is not recommended profile or lead modification. Lightly
the
hardening
embrittlement.
distortion
recommended
and
removed
for hydrogen necessary
because
carburizing
a good
not
tooth
be ground
tooth
contour. in the
is divided
into
root
three
area in which the finishing operation (grinding or Zone C extends a distance C from the root
The
distance
C may
be computed
as
0.250
C-
Pd
Zone
C is the
gears. but
Zone not
gears
specified
in which
B, which
required.
zone B can figure 15. For
zone
result
The
finishing
lies between transition
of
material
quality
for
undercut
and
The values to be specified values for a material grade
Zones from
in a mismatch
that
grades blend
operations
and
A and the
should
not
C, is the
finished
zone
the
3 and
4, it is recommended a minimum
depend on the application 3 gear in the 8- to 12-pitch
88
in which
profile
takes
that
form
tooth
be performed
of undercut
value and range
on highly finishing
to the
that
is allowed
unfinished
or blend
the manufacturing are as follows:
root
in
as illustrated
maximum
be specified
loaded
for blend plan.
values
in
be
radius. Typical
Undercut (maximize in the rangeof) .........
0.005 to 0.007 in.
Blend (maximize up to) ...................
0.002 in.
Blend radius (minimize in the rangeof) .......
0.020 to 0.030 in.
The amount of metal removed from the carburizedareasof the tooth should not exceed20 percent of the total casedepth available.Table XVI givesrecommendedmaximum values for grinding stock. It is recommendedthat the amount of material ground away after hardening always be kept to the minimum that allows the gear to meet the dimensional tolerances. Procedurespresentedin reference 44 should be followed in inslJectingthe gear for alteration of surfacetemper by the finishing process.
3.4.5
Shot Peening
Residual
compressive
surfaces Shot
peen
subject the
stress
to cyclic
tooth
root,
necessary
tensile
rim,
and
for
maximum
fatigue
life shall
exist
in gear
stresses. web
surfaces
of turbopump
power
gears.
The
location
peening and the direction of the shot stream should be clearly specified. In peening roots, the shot stream should be directed radially inward toward the gear center. MIL-S-13165 accurate
size
control
methods
control shot
to
should
of be
the inspection
specified
is recommended; should
not
shot-peening for
process.
shot-peening
to eliminate
hardness
be greater
1/2
be 42
nor
exist.
performance
to 55 on
less
control
quality
human
should
than
Process
than
checked
continuously
during
Rockwell
1/4 of the
requirements
for the
processing.
Automated
variability.
the
fillet
per MIL-S-13165 is recommended for rocket-engine-gear tooth 0.038 in. and larger. For radii of 0.025 to 0.030 in., use number be
is required,
Undersize
tooth Invoke since
no
shot-peening Round
C scale. radius.
of
cast
steel
Nominal
Number
shot
130 shot
roots with fillet radii of 110 size shot. Shot should
and
broken
shot
should
be
eliminated. Shot-peening an Almen root To
strip
should ensure
fillet
area),
heat-treatment should
arc height
be specified proper
shot
the
entire and
be confined
of 0.015A (in gin.
peening gear
pregrind to profile
Multipeening
(peening
the maximum
beneficial
roots
the
of turbopump
with
AA)
an exposure
before
of critical
tooth
and
areas
including
same
residual
surface
(the
most tip,
noncritical with
compressive
areas
89
size 35).
root
should
shot)
and
specify
roughness
area
complete. (sides
should
as shown
important
are
(ref.
Surface
peening
and
different stress
of 4×.
shot
operations
and
of 8 to 12 pitch
time
after
sides,
manufacturing finishing
gears
in the
in table
is the
be peened Subsequent
XIX.
tooth-root after
all
grinding
tip).
should
be used
to obtain
Rim and web surfitces should be shot peened perpendicular to the web surface: use as control an Almen strip height of 0.010A to 0.015A with an exposuretime of 4X (ref. 34). Surface
roughness
3.4.6
after
Configuration
hzformation
)br
manufacturing
necessary information
to
Sketches
configuration
should
be
instrument
allowable
main-power
on
drawing
AA.
shall
be fully
descriptive
of gear
added
to the Table
traces
deviations,
and
gear XI
showing
tolerance
drawing is
an
required bands
to present e:_ample
involute
should
information of
data-block
profile
be made
and
part
lead
of the
gear
gears, detailed
where
grinding
dimensional
of fillets
sketches
and
of the
roots
fillets
is not and
permitted,
roots
include
5 to 10 times
size
15).
Hardness
3.5
test
locations
should-be
indicated
on the drawing.
TESTING
3.5.1
Acceptance
The not Use
have
only
Rockwell met taken
a detrimental hardness
C scale
anywhere
performed to the
effect
may
and
be used
on an actual from
tooth the
tested
part depth
section. outer
acceptance
of
processing
On
surface
hardness
for testing
destructively Case
to
and
to measure
on the uncarburized sample.
prior
material
the
gears
shall
requirements
but
shall
on the gears.
indentor
hardness
samples
or on a test distance
tests
conformance
a 15N
heat-treat
gear,
Testing
quality-assurance
denzonstrate
the
125 gin.
fig. 13).
For ground
on
of gear
block
measuring
(e.g.,
gear
exceed
control the gear configuration. for two types of turbopump gears.
modifications,
the
not
Control
control
data
of
drawing
should
requirements.
A supplementary
(fig.
peening
of the should
at the
core hardness
gears. sample
Core gear,
be established
a carburized
gear,
to
at
the
50 R c .
9O
point
pitch
line
of the
or for testing
hardness
the
case
which
the
depth hardness
must
removed
a hardness
teeth.
case hardness
requirements
on a section by
gear
from
traverse has
a test
(fig.
is considered decreased
be 17)
to be to
Retained austenite content of accessoryand medium power gearsshould be measuredby either visual examination or X-ray diffraction. In casesof conflict, the meastlrementsmade by X-ray diffraction should be used. The austenite content of critical gears such as main-power turbopump gearsshould alwaysbe measuredby X-ray diffraction. Grain sizeshould be determined by the methods noted in ASTM E-112-63. All gears intended for further service should be magnetic-particle inspected per MIL-M-11472, and those with flaws should be rejected.
3.5.2
Performance
Performance actual
The
shall
turbopump
In all tests operated
tests
full
following
verify
operating
conducted at
Testing that
to demonstrate
speed
series
while
the
loaded
of tests
the
gear
system
will
operate
satisfactorily
at
conditions.
by
adequacy
of a new
design,
water
brake,
leaking
seal,
dynamometer,
the
gear train
should
or back-to-back
be
tester.
is recommended:
(1)
Short
run,
low load
(2)
Short
run,
full load
(3)
Full
duration,
(4)
Required
(5)
Ten-percent
(6)
Ten-percent
(7)
Lubricant
(8)
Simulated
full load
qualification
life
overload,
qualification
overload,
duration
flow
life to failure
limits
failure:
plugged
lubrication
jet,
or other
realistic
failure
modes. After the
any gear
design
modifications
evaluation
should
gears after condition
testing usually
examination The
use
problems Gear
tests
following
that
be
through
back-to-back may
should
continued
by
the
back-to-back
by
observation
test
of test
in turbopump hot-fire and static engine can be monitored throughout the test
of the gears of the
indicated
become be
the test
apparent
conducted
lubricant
jet
arrangement after with
mounting also
the gear
instrumentation
parameters:
91
port
series data
incorporated,
examination
runs. series
Gear tooth by periodic
in the
gear case.
is recommended
system
and
are
for
trouble
of
surface visual
shooting
is operational. adequate
to measure
accurately
the
(1)
Shaft
(2)
Lubrication Flow
speed
(input system: rate
Inlet
temperature
Outlet Inlet
temperature pressure
Individual
(3)
Bearing
(4)
Vibration. major
or output).
to distribution
jet pressures
temperatures -
One
manifold
for critical
on critical sensitive
vibration.
However,
jets.
bearings.
accelerometer if
located
resonances
accelerometers located close to the support greater aid in locating incipient problems.
(5)
Shock
intensity.
-
A shock
pulse
meter
are
anywhere expected,
bearings
or other
on the the
for each
tuned
case will detect use
shaft
response
of
multiple
in question
meter
is a
can be of
great aid in discovering bearing fatigue or similar trouble as it develops. Stopping the test prior to failure will prevent extensive damage that might otherwise mask the actual cause of the failure. (6)
Prime mover torque. load, heat generation,
(7)
Audible may
alert
sound.the
test
- This variable often or other degradation
Change crew
in pitch
to watch
often
other
92
may be the first of gear condition. accompanies
parameters
closely.
criterion
a developing
of increasing
trouble
and
APPENDIX Conversion
of U.S. Customary
Units
to SI Units
SI unit
Conversion
kgf
N
9.807
lbf
N
4.448
ft
m
0.3048
in.
cm
2.54
Physical quantity
U.S. customary
Force
Length
A
unit
25.4
mil Mass
Ibm
kg
0.4536
Power
hp
W
745.7
Pressure
mm Hg
N/m 2
133.3
psi (lbf/in. 2)
N/m 2
6895
rpm
rad/sec
0.1047
Rotational
speed
factor a
Btu
J
lbm.°F
kg-K
Stress
psi (lbf/in. 2)
N/m 2
6895
Temperature
oF
K
5 K = - (°F ÷ 459.67) 9
Tensile strength
psi (lbf/in. 2)
N/m 2
6895
Thermal
Btu
J
1054
Torque
in.4bf
N-m
0.1130
Viscosity
centistokes
m 2/sec
1.00xl0 -6
Volume
gal
m 3
3.785x10
Specific heat
aMultiply
energy
value
4184
given m U.S. customary
unit
by conversion
factor
to obtain
-3 equiva-
lent value in SI unit. For a complete listing of conversion factors, see Mechtly, E.A.: The International System of Units. Physical Constants and Conversion Factors.
Second
revision,
NASA
SP-7012,
1973.
93
94
APPENDIX
B
GLOSSARY Symbol
Definition
AA
arithmetic
a
addendum
D
pitch diameter
Db
base circle diameter
Do
outside diameter
d
(1) dedendum (2) pitch diameter of pinion (3) overhang (fig. 3)
db
base circle diameter
do
outside diameter
EP
extreme
F
face width of gear
h
lubricant
ht
tooth whole depth (total
J
geometry
K
tooth pitting index compressive stress)
average
of gear of gear
of gear
of pinion
of pinion
pressure
film thickness depth)
factor for bending
strength
(preliminary
m
modifying
factor
Ko
modifying
factor for overload
modifying
factor for size
Kt
modifying
factor for temperature
Kv
modifying
factor for dynamic
K
95
for load distribution
toad
design
value
representative
of
Definition
S__ymbol mG
gear ratio
P
pitch; Hertz contact
pressure number
diametral
of teeth
pitch, Pd = pitch diameter,
in.
PA
pressure angle
PLV
pitchline
PV
scoring index, defined
in note on Table V
PVT
scoring index, defined
in note on Table V
ppi
pounds per inch (of face width)
Rc
hardness
ref.
dimension
S
bearing span
Sac
allowable
Sc
compressive
Stu
ultimate
Sty
yield tensile strength
s
surface roughness
t
tooth thickness
TIF
true involute
UL
unit load (preliminary
Wt
total tangential
Y
tooth form factor
velocity
on Rockwell
"C" scale
given for reference
compressive
only; not to be measured
stress
stress
tensile strength
form design value representative
tooth load
h/s
96
of bending
stress)
Symbol
Definition
15N
hardness scale for the superficial Rockwell 15N scale results in a very small indentation)
Material
hardness
test (use
of the
Identification
A356-T61
high-strength
A357-T61
high-strength cast aluminum developed by careful control T61
AISI 410 440C
AISI designations
for corrosion-resistant
AISI 3310 4140 4340 4620
AISI designations
for low-alloy carbon
cast aluminum
alloy, temper
T61
alloy in which special properties of casting and chilling techniques;
hardenable
can be temper
steels
steels
8620 9310 9315 AMS5630
wrought
corrosion-
AMS 6260 6265 6470
wrought
low-alloy
Berylco 25
beryllium-copper
carburizing
steel
and heat-resistant
steel per AMS 5630
steels per AMS 6260, 6265, and 6470 respectively
alloy made by Kawecki
low-carbon-content
steel
that
Berylco Industries,
can be treated
to cause
Inc. the
metal
to
absorb carbon into the surface, thereby increasing surface hardenability while maintaining a weaker, softer, but tougher core CRES
corrosion-resistant
GH2
gaseous hydrogen
Inconels
trade name of International
IRFNA
inhibited
LH2
liquid hydrogen,
steel
Nickel Co. for austenitic
red fuming nitric acid, propellant propellant
97
nickel-base
grade per MIL-P-7254
grade per MIL-P-27201
alloys
Identification
Material LO2, LOX
liquid oxygen,
N2 H4
hydrazine,
N2 04
nitrogen
tetroxide,
nital
solution
of concentrated
nitriding
steel
propellant
propellant
grade per MIL-P-25508
grade per MIL-P-26536
propellant
grade per MIL-P-26539
nitric acid in alcohol
steel alloyed with nitride-forming chromium, molybdenum, vanadium,
elements such as aluminum, and tungsten. Exposure of the
alloy to active nitrogen results in a thin hard case that is especially wear resistant. Precautions are necessary to avoid chipping. Cost is higher than that for carburizing. Oronite
262
zinc dialkyl dithiophosphate Co.
additive,
Oronite
Div., Chevron
RP-1
kerosene-base
fuel, propellant
grade per MIL-P-25576
Tens-50
high-strength
aluminum
UDMH
unsymmetrical
Chemical
alloy for casting
dimethylhydrazine,
propellant
grade
per MIL-P-25604
Title
Specification Materials 1 AMS 3132
Varnish,
Synthetic
AMS 3170
Thinner,
Alcohol-Ester
AMS 5630
Bars and Forgings - 17 Cr-0.5 Mo (0.95-1.20
AMS 6260
Bars,
Forgings,
(0.07-0.13 AMS 6265
Bars,
AMS 6470
C).
Mech.
Tubing-3.25
Ni-l.2
Cr-0.12
Mo
and
Mech.
Tubing-3.25
Ni-1.2
Cr,0.12
Mo
C) Premium
Quality
C)
Bars, Forgings, (0.38-0.43
Preventive.
and
Forgings,
(0.07-0.13
Resin Corrosion
Consumable
and Mech. Tubing,
Nitriding-
Electrode
Vacuum
1.6 Cr-0.35
Melted.
Mo-1.13
A1
C)
1Specifications designated AMS are published by Society of Automotive Engineers, Inc., 2 Pennsylvania Plaza, New York, NY 10001. Military specifications are published by the Department of Defense, Washington, DC 20025.
98
Title
Specification Materials
MIL-C-16173 MIL-L-6081
Corrosion (ASG)
Preventive
Compound,
Solvent
Cutback,
Lubricating
Oil, Jet Engine,
MIL-L-6086
Lubricating
Oil, Gear, Petroleum
Base.
MIL-L-7808
Lubricating
Oil, Aircraft
Engine, Synthetic
MIL-L-25336
Lubricating Strength.
Oil, Aircraft
MIL_-25576
Propellant,
Kerosene.
MIL@-27401
Propellant
Pressurizing
Agent, Nitrogen.
Propellant
Pressurizing
Agent, Helium.
MIL-P-27407
(USAF)
Processesand
Test Methods
Turbine Turbine
Engine,
ASTMD-2596-69
Extreme-Pressure Properties of Lubricating Measurement of. ASTM 17 (1969).
ASTME112-63
Estimating
Federal
Test Method
No. 791, Method Federal
Test Method
No. 791, Method
Std.
6508.1
MIL-C-26074 MIL-M-11472
Std.
6503.1
Base.
Synthetic
Base, High Film
Grease (Four Ball Method),
Grain Size of Metals. ASTM, 1963.
Load Carrying Capacity (Mean Hertz Load). Jan. 15, 1969. Contained in FTM Std. No. 791B, Change Notice 1, Oct. 15, 1969. Load Carrying Capacity of Lubricating Oils (Ryder Gear Machine). Jan. 15, 1969. Contained in FTM Std.No. 791B, Change Notice 1, Oct. 15, 1969. Coatings,
(ORD)
Cold-Application.
Electroless
Nickel, Requirements
Magnetic Particle Inspection;
MIL-S-13165
Shot Peening
QQ-C-320a (FederalSpecification)
Chromium
Process for Ferromagnetic
of Metal Parts.
Plating (Electrodeposited).
99
for. Materials.
Identification
Vehicles, Pumps, and Engines Agena
upper
stage
for
Atlas
and
Thor
launch
vehicles;
uses LR81-BA-11
engine Atlas (SLV-3)
launch
vehicle
vernier,
using
MA-5
and 1 sustainer
engine
engines;
system
boosters
containing
provide
2 booster,
2
330 000 to 370 000
lbf thrust; sustainer, 60 000 lbf thrust; uses LOX/RP-1 ; engine system manufactured by Rocketdyne Division, Rockwell International Corp.
Centaur
high-energy
upper
stage for Atlas
and Titan
launch
vehicles;
uses 2
RL10 engines H-1
engine
for S-IB; 200 000 lbf thrust;
uses LOX/RP-1
; manufactured
by
Rocketdyne LR81-BA- 11
engine for Agena upper stage; 15 000 lbf thrust; uses IRFNA/UDMH; manufactured by Bell Aerospace Company, Division of Textron
LR-87-AJ-5
Aerojet
engine
for the first stage of the Titan II; uses N_O4/A-50*
and
develops 215 000 lbf thrust LR-91-A J-5
Aerojet
engine
and develops
for the second
stage of the Titan
II; uses N204/A-50*
100 000 lbf thrust
Mark 3
turbopump for the engines in the Atlas, Thor, manufactured by Rocketdyne
Mark 4
turbopump
for
the
Atlas
sustainer
and Saturn IB boosters;
engine;
manufactured
by
Rocketdyne RL10
engine for Centaur upper stage; manufactured by Pratt & Whitney
15 000 lbf thrust; uses LOX/LH2; Aircraft Division of United Aircraft
Corp. S -IB
first stage (booster)
of the Saturn IB vehicle; uses a cluster
of eight H-1
engines Thor
launch
vehicle
LOX]RP-1; Titan Ii
launch
using
MB-3 engine
system;
engine system manufactured
vehicle
engines developed
using
the
by Aerojet
"50[50 mixture of UDMH and hydrazine.
100
LR-87-AJ
170 000
lbf thrust; uses
by Rocketdyne and
Liquid Rocket
LR-91-AJ Co.
series of rocket
Abbreviation AGMA AISI AMS ASA ASLE ASME ASTM SAE
Identification American
Gear Manufacturers
Association
American
Iron and Steel Institute
Aerospace
Material Specifications
American
Standards
American
Society
of Lubrication
American
Society
of Mechanical
American
Society
for Testing
Association
Society of Automotive
101
(published
Engineers Engineers
and Materials
Engineers
by SAE)
C'q
REFERENCES 1. Anon.: Terms, Definitions,
Symbols,
2. Dudley,
D. W., ed.: Gear Handbook.
3. Anon.:
Design Procedure
411.02, 4.
and Abbreviations. McGraw-Hill
for Aircraft
Engine
AGMA 112.04, AGMA, Aug. 1965.
Book Co., '1962. and Power
Take-Off
Spur and Helical Gears. AGMA
AGMA, Sept. 1966.
Anon.: AGME Gear Handbook. Vol. 1 - Gear Classifications, Unassembled Gears. AGMA 390.03, AGMA, Jan. 1973.
5. McIntire,
W. L.; and Malott,
R. C.: Advancement
Materials,
and Measuring
of Spur Gear Design Technology.
Methods
for
USAAVLABS
Tech. Rep. 66-85, U.S. Army Aviation Lab. (Fort Eustis, VA), 1966. 6. McIntire,
W. L.; and Malott,
R. C.: Advancement
Tech. Rep. 68-47, U.S. Army Aviation
of Helical Gear Design Technology.
Lab. (Fort Eustis, VA), 1968.
7. Coleman, W.; Lehmann, E. P.; Mellis, D. W.; and Peel, D. M.: Advancement Bevel Gear Technology. USAAVLABS Tech. Rep. 69-75, U.S. Army Aviation Oct. 1969. 8. Anon.:
Information
225.01, 9.
Sheet
for Strength
of Spur, Helical, Herringbone
J. B.; and Dudley,
D. W.: Results
Teeth. J. Eng. Ind. Trans. ASME, SeriesB, D. W.: Practical
of 15-Year Program
12. Costomiris, PWA-3718, 13. Bodensieck,
14. Anon.!
and Bevel Gear Teeth.
AGMA
of Flexural
Fatigue Testing
of Gear
vol. 86, 1964, pp. 221-239.
Gear Design. McGraw-Hill
11. Anon.: Information Sheet for Surface Durability Gear Teeth. AGMA 215.01, AGMA, Sept. 1966.
presented
of Straight and Spiral Lab. (Fort Eustis, VA),
AGMA, Dec. 1967.
Seabrook,
10. Dudley,
USAAVLABS
Book Co., 1954. (Pitting)
of Spur, Helical, Herringbone,
and Bevel
G.; Daley, D.; and Grube, W.: Heat Generated in High Power Reduction Gearing. Pratt & Whitney Aircraft Div., United Aircraft Corp. (East Hartford, CT), June 1969. E. J.: Specific at 1965 Aerospace
Information
AGMA 217.01,
Film Thickness
-An
Index
of Gear Tooth
Surface
Gear Comm. Tech. Div. Meeting, AGMA (Denver,
Sheet - Gear Scoring Design Guide for Aerospace
Deterioration.
Paper
CO), Sept. 1965.
Spur and Helical Power Gears.
AGMA, Oct. 1965.
15. Borsoff, V. N.; and Gode t, M. R.: A Scoring 147-153.
Factor
103
for Gears. ASLE Trans., vol. 6, no. 2, 1963, pp.
16. Lemanski,A. J.: A Comparison of GearScoringIndices.VertolDiv.,BoeingCo.(Morton,PA),Feb. 1965. 17. Hartman,M. A.: Advancesin Aerospace PowerGears.PowerTransmission
Design,
vol. 9, no. 11,
Nov. 1967, pp. 40-47.
18. Butner,
M. F." Propellant Lubrication Properties Pts. I and II (AD 259143), June 1962.
19. Lorvick, R. R.: Lubricating
Investigation,
Final Report.
Rep. WADD-TR,61-77,
Gears. Mach. Des., vol. 42, no. 17, July 1970, pp. 108-117.
20.
McCain, J. W.; and Alsandor, E.: Analytical Aspects of Gear Lubrication on the Disengaging Side. ASLE paper 65-LC-16, ASLE and ASME Lubrication Conf. (San Francisco, CA), Oct. 18-20, 1965.
21.
McIntire, W. L.: How to Reduce (Indianapolis, IN), Feb. 1964.
22. Dudley,
Gear
Vibration
W. M.; and Hall, Ira K., Jr.: Analysis
Failures.
of Lateral
Allison
Vibrations
ASME paper 66-MD-4, ASME Design Eng. Conf. and Show (Chicago, 23.
Reiger, 1964.
24.
Anon.: Tooth Proportions AGMA, Aug. 1968.
25.
Anon.: Tooth Proportions for Fine-Pitch 207.05, AGMA, June 1971.
N.: Vibration
Characteristics
of Geared
for Coarse-Pitch
Transmission
Involute
Involute
Div.,
General
Motors
of Gears and Rimmed
28.
Wheels.
IL), May %12, 1966.
Systems.
AGMA
109.14,
Spur Gears (ANSI B6.1-1968).
AGMA, Oct.
AGMA 201.02,
Spur and Helical Gears (ANSI B6.7-1967).
26. Dolan, T. J.; and Broghamer, E. I.: A Photoelastic Study of the Stresses in Gear Tooth of Illinois Eng. Expt. Sta. Bull. 335, Univ. of Illinois (Urbana, IL), Mar. 1942. *27.
Corp.
AGMA
Fillets. Univ.
Hartman, M. A.: Profile Modification for Heavily Loaded Gears Under Dynamic Conditions. Rocketdyne Div., North American Rockwell Corp. (Canoga Park, CA), Nov. 1967 (unpublished). Pollack, C.: Better 1968, pp. 78-80.
Surface
Lavoie, F. J.: High Velocity
Integrity
- Secret
of Part Reliability.
Machinery,
vol. 75, no. 3, Nov.
Forging of Gears. Mach. Des., vol. 40, no. 28, Dec. 1968, pp. 146-151.
Burroughs, L. R.; and Fitzgerald, P. C.: Evaluation of Advanced Gear Forging Techniques. USAAVLABS Tech. Rep. 69-11, U.S. Army Aviation Lab. (Fort Eustis, VA), Apr. 1969.
*Dossier
for design
available
for inspection
criteria
monograph
at NASA
Lewis
"Liquid Research
Rocket Center,
Engine
Turbopump
Cleveland,
104
Ohio.
Gears."
Unpublished.
Collected
source
material
31. Parkinson,F. L.: Evaluationof High-Energy-Rate ForgedGearsWithIntegralTeeth.
USAAVLABS
Tech. Rep. 67-11, U.S. Army Aviation Lab. (Fort Eustis, VA), Mar. 1967. 32. Anon.:
Recommended
Procedure
for Carburized
Industrial
Gearing.
AGMA 246.01A,
AGMA, Nov.
1971. 33. Straub,
J. C.: Shot Peening
34. Anon.:
Shot Peening. Wheelabrator
35. Anderson, Utilization 36.
Bush, J.
in Gear Design,
1964. AGMA 109.13,
Corp. (Mishawaka,
AGMA, June 1964.
IN), 1965.
B. N.; and Hartman, M. A.: Multipeening of Surfaces To Extend Fatigue Life. Technology Docket NAR 50477, Rocketdyne Div., North American Rockwell Corp., Mar. 1966. J.;
Mattson,
R. L.; and Roberts,
J. G.: Shot Peening
Treatments.
U.S. Patent
3,073,022,
assigned to General Motors Corp., issued Jan. 1963. 37.
Anon.:
Turbopump
Monograph,
Systems
for
Liquid
39. Buckingham, Campbell,
41.
Anon.:
Engines.
NASA
Space
Vehicle
Design
Criteria
NASA SP-8107 (to be published).
38. Anon.: Liquid Rocket Engine Turbopump NASA SP-8048, Mar. 1971.
40.
Rocket
E.: Analytical
Mechanics
Bearings. NASA Space Vehicle
of Gears. McGraw-Hill
Book Co., 1949.
M. E.; Loser, J. B.; and Sn_egas, E.: Solid Lubricants.
Maag Gear Book. Maag Gear Wheel Co. (Zurich,
Design Criteria Monograph,
NASA SP-5059, May 1966.
Switzerland),
Dec. 1965.
J
42. Sigg, H.: Profile _nd Longitudinal 43. Lyman, Society 44. Anon.:
T., ed.: Metals Handbook.
C6rrections
on Involute
Vol. 1: Properties
Gears. AGMA
and Selection
109.6, AGMA, Oct. 1965.
of Metals.
for Metals (Metals Park, OH), 1961. Surface Temper
Inspection
Process. AGMA 230.01,
105
AGMA, Mar. 1968.
Eighth ed., American
106
NASA SPACE VEHICLE DESIGN CRITERIA MONOGRAPHS ISSUED TO DATE
ENVIRONMENT SP-8005
Solar Electromagnetic
SP-8010
Models of Mars Atmosphere
SP-8011
Models of Venus Atmosphere
SP-8013
Meteoroid Environment March 1969
SP-8017
Magnetic
SP-8020
Mars Surface Models (i968),
SP.8021
Models of Earth's
SP-8023
Lunar Surface Models, May 1969
SP-8037
Assessment
and Control
of Spacecraft
SP-8038
Meteoroid
Environment
Model-1970
October
Radiation,
Fields-Earth
Revised May 1971
(1967),
May 1968
(1972),
Revised September
Model-1969
(Near
and Extraterrestrial,
Earth
1972
to Lunar
Surface),
March 1969
May 1969
Atmosphere
(90 to 2500 km), Revised March
Magnetic
Fields, September
(Interplanetary
1973
1970
and Planetary),
1970
SP-8049
The Earth's
Ionosphere,
March 1971
SP.8067
Earth Albedo and Emitted
Radiation,
July 1971
SP-8069
The Planet Jupiter
December
1971
SP.8084
Surface
(1970),
Atmospheric
Extremes
(Launch
and Transportation
Areas),
May 1972 SP-8085
The Planet Mercury
(1971),
SP-8091
Thd Planet Saturn (1970),
June 1972
SP_8092
Assessment June 1972
of Spacecraft
and Control
107
March 1972
Electromagnetic
Interference,
SP-8103
ThePlanetsUranuS , Neptune , andPluto(1971),November 1972
SP-8105
Spacecraft
•'
Thermal
.
:
Control,
May 1973
STRUCTURES •
SP-8001
Buffeting
SP-8002
Flight-Loads
SP-8003
Flutter,
SP-8004
Panel Flutter,
Revised June 1972
SP-8006
Local Steady
Aerodynamic
SP-8007
Buckling of Thin-Walled
SP-8008
Prelaunch
Ground Wind Loads, November
SP-8009
Propellant
Slosh Loads, August 1968
SP-8012
Natural
SP-8014
Entry Thermal
SP-8019
Buckling of Thin-Walled
Truncated
SP-8022
Staging Loads, February
1969
SP-8029
During Atmospheric
Ascent, Revised November
Measurements
During
Buzz, and Divergence,
Vibration
Aerodynamic May 1969
Launch
Circular Cylinders,
August
and Rocket-Exhaust
1965
1968
Cones, September
Heating
SP-8031
Slosh Suppression,
SP-8032
Buckling of Thin-Walled
SP-8035
Wind Loads During Ascent, June. 1970
SP-8040
Fracture
SP-8042
Meteoroid
SP-8043
Design-Development
Excitation,
1968
During Launch
February
1969
May 1969 Doubly
Curved Shells, August
of Metallic Pressure Vessels, May 1970
108
1968
1968
Transient
Damage Assessment,
1964
and Exit, May 1965
Revised August
September
SP-8030
Control
and Exit, December
Loads During Launch
Loads From Thrust
1970
July 1964
Modal Analysis,
Protection,
,
May 1970
Testing, May 1970
1969
and Ascent
SP-8044
Qualification Testing,May1970
SP-8045
Acceptance Testing,April 1970
SP-8046
LandingImpactAttenuationfor Non-Surface-Planing Landers,April 1970
SP-8050
StructuralVibrationPrediction,June1970
SP-8053
NuclearandSpace RadiationEffectsonMaterials, June1970
SP-8054
SpaceRadiationProtection,June1970
SP-8055
Preventionof CoupledStructure-Propulsion Instability(Pogo),October 1970
SP-8056
FlightSeparation Mechanisms, October1970
SP-8057
StructuralDesignCriteriaApplicableto aSpaceShuttle,Revised March 1972
SP-8060
Compartment Venting,November 1970
SP-8061
Interactionwith UmbilicalsandLaunchStand,August1970
SP-8062
EntryGasdynamic Heating,January1971
SP-8063
Lubrication,Friction,andWear,June1971
SP-8066
Deployable Aerodynamic Deceleration Systems, June1971
SP-8068
BucklingStrengthof StructuralPlates,June1971
SP-8072
AcousticLoadsGenerated by thePropulsionSystem,June1971
SP-8077
Transportation andHandlingLoads,September 1971
SP-8079
StructuralInteractionwithControlSystems, November1971
SP-8082
Stress-Corrosion Crackingin Metals,August1971
SP-8083
DiscontinuityStresses in MetallicPressure Vessels, November1971
109
SP-8095
PreliminaryCriteria for the Fracture Control of SpaceShuttle Structures, June1971
SP-8099
Combining AscentLoads,May1972
SP-8104
StructuralInteractionWith Transportationand HandlingSystems, January1973
GUIDANCE ANDCONTROL SP-8015
Guidance andNavigation for EntryVehicles,November 1968
SP-8016
Effectsof StructuralFlexibilityon Spacecraft ControlSystems, April 1969
SP-8018
Spacecraft Magnetic Torques,March1969
SP-8024
Spacecraft Gravitational Torques,May1969
SP-8026
Spacecraft StarTrackers, July 1970
SP-8027
Spacecraft RadiationTorques,October1969
SP-8028
EntryVehicleControl,November 1969
SP-8033
Spacecraft EarthHorizonSensors, December 1969
SP-8034
Spacecraft MassExpulsionTorques,December 1969
SP-8036
Effectsof StructuralFlexibility on LaunchVehicleControlSystems, February1970
SP-8047
Spacecraft SunSensors, June1970
SP-8058
Spacecraft Aerodynamic Torques,January1971
SP-8059
SpacecraftAttitude Control DuringThrustingManeuvers, February 1971
SP-8065
TubularSpacecraft Booms(Extendible,ReelStored);February1971
SP-8070
Spaceborne DigitalComputerSystems, March1971
SP-8071
Passive Gravity-Gradient LibrationDampers, February1971
SP-8074
Spacecraft SolarCellArrays,May1971
110
SP-8078
Spaceborne ElectronicImagingSystems, June1971
SP-8086
Space VehicleDisplaysDesignCriteria,March1972
SP-8096
Space VehicleGyroscope Sensor Applications, October1972
SP-8098
Effectsof StructuralFlexibility on Entry VehicleControlSystemg, June1972
SP-8102
Space VehicleAccelerometer Applications, December 1972
CHEMICALPROPULSION SP-8087
LiquidRocketEngineFluid-Cooled Combustion Chambers, April 1972
SP-8081
LiquidPropellant GasGenerators, March1972
SP-8109
Liquid RocketEngineCentrifugalFlowTurbopumps, December1973
SP-8052
LiquidRocketEngineTurbopumpInducers, May 1971
SP-8110
LiquidRocketEngineTurbines,January1974
SP-8048
LiquidRocketEngineTurbopumpBearings, March1971
SP-8101
Liquid RocketEngineTurbopumpShaftsandCouplings,September 1972
SP-8094
LiquidRocketValveComponents, August1973
SP-8097
LiquidRocketValveAssemblies, November1973
SP-8090
LiquidRocketActuatorsandOperators, May1973
SP-8080
LiquidRocketPressure Regulators, ReliefValves,CheckValves,Burst Disks,andExplosive Valves,March1973
SP-8064
SolidPropellantSelection andCharacterization, June1971
SP-8075
SolidPropellantProcessing Factorsin RocketMotor Design,October 1971
SP-8076
SolidPropellant GrainDesignandInternalBallistics, March1972
SP-8073
SolidPropellant GrainStructuralIntegrityAnalysis,June1973
111
SP-8039
SolidRocketMotorPerformance AnalysisandPrediction, May 1971
SP.8051
SolidRocketMotorIgniters,March1971
SP-8025
SolidRocketMotorMetalCases, April 1970
SP-8041
Captive-Fired Testingof SolidRocketMotors,March1971
,
1 12
NASA-Langley, 1974
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