2. TRANSMISSION SYSTEM
• The mechanism that transmits the power developed by the engine of automobile to the engine to the
driving wheels is called the TRANSMISSION SYSTEM (or POWER TRAIN).
• It is composed of
Clutch
The gear box
Propeller shaft
Universal joints
Rear axle
Wheel
Tyres
3. LAYOUT OF A TRANSMISSION
SYSTEM
Engine
Transmission
Drive Shaft
Rear Wheel
Differential
U-Joint
Clutch
4. REQUIREMENTS OF TRANSMISSION
SYSTEM
Provide means of connection and disconnection of engine with rest
of power train without shock and smoothly.
Provide a varied leverage between the engine and the drive wheels
Provide means to transfer power in opposite direction.
Enable power transmission at varied angles and varied lengths.
Enable speed reduction between engine and the drive wheels in the
ratio of 5:1.
Enable diversion of power flow at right angles.
Provide means to drive the driving wheels at different speeds when
required.
6. CLUTCH
A clutch is a mechanism
which enables the rotary
motion of one shaft to be
transmitted at will to second
shaft ,whose axis is
coincident with that of first.
It is located between the
engine and the
transmission.
7. CLUTCH
Requirements of a clutch:
1. Torque Transmission
2. Gradual Engagement
3. Heat Dissipation
4. Dynamic Balancing
5. Vibration damping
6. Free pedal play
7. Lightness.
Principle of Operation:
Works on the principle of friction.
When two friction surfaces are
brought in contact with each other and
pressed, they unite due to friction
between them.
If one is revolved, the other one will
also revolve.
8. TYPES OF CLUTCH
Single Plate Clutch
A single plate is commonly used in cars and light
vehicles.
It has only one clutch plate which is mounted on
the splines of the clutch shaft.
A flywheel is mounted on the crankshaft of the
engine. A pressure plate is connected to the
flywheel through the bolts and clutch springs. It
is free to slide on the clutch shaft with the
movement of clutch pedal.
When clutch is in engaged position, the clutch
plate remains gripped between flywheel and
pressure plate.
Friction linings are provided on both the sides of
10. TYPES OF CLUTCH
In a cone clutch, the driver is keyed to the driving shaft by a
sunk key and has an inside conical surface or face which
exactly fit into the outside conical surface of the driven.
The driven member resting on the feather key in the driven
shaft, may be shifted along the shaft by a forked lever.
In order to engage the clutch by bringing the two conical
surfaces in contact. Due to the frictional resistance set up at
the contact surface, the torque is transmitted from one shaft
to another shaft.
In some cases, a spring is placed around the driven shaft in
contact with the hub of the driven.
This spring holds the clutch faces in contact and maintains
the pressure between them, and the forked lever is used to
disengagement of the clutch.
15. GEARBOX
To provide the high torque at the time of starting, hill climbing, accelerating and
pulling a load since high tractive effort is needed.
It permits engine crankshaft to revolve at high speed, while the wheels turn at
slower speeds.
Variable torque by set of gears.
Vehicle speed can be changed keeping engine speed same with certain limit.
The transmission also provides a neutral position so that the engine and the road
wheels are disconnected even with the clutch in the engaged position.
A means to back the car by reversing the direction of rotation of the drive is also
provided by the transmission.
16. Depending on the size of the vehicles, the size
of the gears also varies. There are low gears
covering a shorter distance and are useful
when speed is low. There are high gears also
with larger number of teeth.
