Gears Pp Presentation

GEARS Introduction to Engineering and Technology Concepts

GEARS • A wheel with a number of teeth wrapped around the circumference. • When two gears are meshed together, the rotation of driver and follower are always opposite.

GEARS vs. PULLEYS • Gears do not “creep” or “slip” • Gears change direction of motion • Mechanical advantage is calculated by counting number of teeth

GEARS • Common uses include:

– Transmit motion – Change direction of motion – Magnify output speed – Magnify output force

GEAR USES

You can see effects 1, 2 and 3 in the figure above. In this figure, you can see that the two gears are rotating in opposite directions, that the smaller gear is spinning twice as fast as the larger gear, and that the axis of rotation of the smaller gear is to the right of the axis of rotation of the larger gear.

GEAR TYPES • Spur Gears • Idler Gear

GEAR TYPES

GEAR TYPES

GEAR TYPES

GEAR TYPES

GEAR TRAINS A series of 2 or more gears is called a gear train.

In a gear train we have a gear known as the driver and one known as the follower . Driver - is the gear that has the force or motion input. Follower - is the gear that results in the force or motion output.

GEAR TRAINS Gear Ratio = Driver : Follower For example, if a motor is attached to a gear with 60 teeth and this gear is then attached to a gear with 20 teeth that drives a wheel, our gear ratio is 60:20, or more accurately 3:1

GEAR TRAINS If the driver is smaller than the follower, force is multiplied. If the driver is bigger than the follower, speed is multiplied.

GEAR TRAINS

The purple gear in the train is actually made in two parts. A small gear and a larger gear are connected together, one on top of the other. Gear trains often consist of multiple gears in the train.

GEAR TRAINS

GEAR TRAINS

GEAR TRAINS Calculating Speed Change • Sd X T d = S f X T f Sd= Speed of Driver Td

=

Teeth of Driver

Sf = Speed of Follower Tf = Teeth of Follower

• Sd = Sf X (Tf ÷ Td)

GEAR TRAINS A driver gear is moving at a rate of 500 rpm. If the driver gear has 10 teeth and the follower has 5 teeth, how fast is the follower going?

GEAR TRAINS A driver gear is moving at a rate of 300 rpm. If the driver gear has 15 teeth and the follower has 50 teeth, how fast is the follower going?

GEAR TRAINS Calculating Force Change (Mechanical Advantage) MA = Tf ÷ Td

GEAR TRAINS A driver gear is moving at a rate of 500 rpm. If the driver gear has 10 teeth and the follower has 5 teeth, what is the mechanical advantage?

GEAR TRAINS A driver gear is moving at a rate of 300 rpm. If the driver gear has 15 teeth and the follower has 50 teeth, what is the mechanical advantage?

GEAR TRAINS Number of Teeth • Gear A = 32 • Gear B = 8 • Gear C = 8 • Speed or Force Multiplier?

GEAR TRAINS

If a force of 10N is applied to the driver, what is the turning force that results on the shaft of the follower?

GEAR TRAINS

If a force of 110N is applied to the driver, what is the turning force that results on the shaft of the follower?