• Gear Terminology

Gear Drive

THE GEAR RATIO

• It is defined as the ratio of the speed of driven gear to the speed of driving gear.

• It is denoted by G

Spur Gears

Spur gears have teeth cut parallel

to the axis of the shaft.

They are used to transmit power

between parallel shafts

• In helical gears, tooth are cut at an angle to the axis of the shaft.

• They are used to transmit power between parallel shafts

Helical Gears

• Bevel gears are used to connect two non parallel shafts with intersecting axes..

• They are mainly used when shafts are at right angles to each other

Bevel Gears

• Worm gears are used for power transmission between two non intersecting shaft with right angles to each other.

• It consist of a worm and worm wheel

• Worm is a threaded screw• Worm wheel is a toothed

wheel

Worm Gears

Gear Trains

• Simple Gear train

• Compound Gear Trains

• Reverted Gear Trains

• Epicyclic gear Trains

Single Plate Clutch• A clutch is a device used to connect a

driving shaft to a driven shaft.

• Without stopping the driving shaft, the

driven shaft can be started or stopped.

• It transmit power by friction.

• It is used in automobiles to connect the

engine to the shaft.

• When the pressure plate is pulled back, the

contact between the flywheel and clutch

plate breaks and then flywheel rotates

without driving the driven shaft.

Friction Disc• When power is to be transmitted using friction

disc, it is required to increase the force of

friction between the contact surfaces.

• It is used when the power to be transmitted

between the two shafts is very small.

• Slip occurs between the disc when

transmission increases.

• Hence friction disc is not a positive drive

• It is not used when constant velocity ratio is

required.