Answer 3_power May_ 2009

Suez Canal University Faculty of Engineering Port Said Time : 3 hours



Production Engng & Mechanical Design Dept. Machine Design ( Code PRD 327 ) 3rd Year ( Power Dept. ) May 2009

Answer All the questions and assume any missing data you find it necessary to complete your answer The quality of the needed drawing has a direct influence in the evaluation of the question mark

Question No. 1

30 Marks

1 – A tilting 5 pad bearing is required to support a shaft 0.125 m diameter carrying a steady load of 2 kN during running . the shaft rotates in one direction at 120 rev/s . It is required that the bearing be designed for an oil viscosity grade No. 68 entering at 50 C o. with viscosity index of 95. The lubricant is supplied in the form of flooded feed The Start up load of 200 N is to be expected . The inner diameter is 0.14 m. Bearing misalignment is expected to be minimal . d with inlet temperature of 50 C o . and the drain temperature Tout and the pad feed temperature Tf are assumed to be 70 C o ) . N.B. The Vogel’s Eqn. Constants are as follows : K= 1.04916x10-4

, B= 791.0576 , θ = 85.4988

It is required to present a full design of that bearing. Draw a neat sketch showing the general layout and the configuration of the final design of the off –set pads thrust bearing .

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2

3

4

5

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Question No. 2

25 Marks

Design and draw a protective type of cast iron flange coupling for a steel shaft transmitting 15 kW at 200 r.p.m. and having an allowable shear stress of 40 MPa. The working stress in the bolts should not exceed 30 MPa. Assume that the same material is used for shaft and key and that the crushing stress is twice the value of its shear stress. The maximum torque is 25% greater than the full load torque. The shear stress for cast iron is 14 MPa.

Present a full design and a sectional drawing for the coupling ( in two pages )

Protective Type Flange Coupling 8

2. Design for key

9

3. Design for flange Let the thickness of flange

( tf ) =

0.5 d.

10

Question No. 3

5 Marks

Calculate the length of a Cross Belt Drive , consider in your answer the following notations

r1 and r2 x

= =

Radii of the larger and smaller pulleys, Distance between the centers of two pulleys (i.e. O1, O2),

L

=

Total length of the belt.

and ,

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Question No. 4

15 Marks

An electric motor drives an exhaust fan. Following data are provided :

Calculate the width of 5 mm thick flat belt. Take permissible stress for the belt material as 2.3 MPa.

N.B

14

15

Question No. 5

25 Marks

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Imax •

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