This document defines and describes different types of gears used to transmit power between parallel or intersecting shafts, including spur gears, helical gears, bevel gears, worm gears, and gear trains. It also explains the components and functioning of single plate clutches used to connect driving and driven shafts, allowing the driven shaft to be engaged and disengaged without stopping the driving shaft. Finally, it provides details on friction discs used for power transmission where only small amounts of power need to be transferred and slippage can occur under higher loads.

1. • Gear Terminology
Gear Drive

2. 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

3. Spur Gears
Spur gears have teeth cut parallel
to the axis of the shaft.
They are used to transmit power
between parallel shafts

4. • 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

5. • 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

6. • 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

7. Gear Trains
• Simple Gear train

8. • Compound Gear Trains

9. • Reverted Gear Trains

10. • Epicyclic gear Trains

11. 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.

12. 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.