Transmission System
Transmission System
Transmission System
Clutch is used to engage or disengage the engine to the transmission or gear box.
When the clutch is in engaged position, the engine power or rotary motion of
engine crankshaft is transmitted to gear box and then to wheels.
When clutch is disengaged, the engine power does not reach to gear box (and to
wheels) although engine is running.
Clutch is also used to allow shifting or changing of gears when vehicle is running.
For shifting gears, clutch is first disengaged then gear is shifted and then clutch is
engaged.
Clutch has to be disengaged to stop the vehicle and also at the time of idling.
Principle of Clutch
It operates on the principle of friction. When two surfaces are brought
in contact and are held against each other due to friction between
them, they can be used to transmit power.
If one is rotated, then other also rotates. One surface is connected to
engine and other to the transmission system of automobile.
Thus, clutch is nothing but a combination of two friction surfaces.
Requirement of Clutch
It should be able to transmit the maximum torque of the engine.
It should engage gradually to avoid sudden jerks.
It should be able to dissipate a large amount of heat generated during clutch operation.
It should be dynamically balanced, particularly in the case of high-speed engine clutches.
It should have a suitable mechanism to damp vibrations and to eliminate noise produced during
power transmission.
It should be as small as possible so that it will occupy minimum space.
It should be easy to operate requiring as little exertion as possible on the part of the driver.
It should be made as light as possible so that it will continue to rotate for any length of time after
the clutch has been disengaged.
It must be trouble-free and have longer life.
It must be easy to inspect, adjust, and repair.
Clutch Friction Lining material and their Necessity
Wet Clutch
Clutches based on operation
Mechanical operation
Electromagnetic operation
Hydraulic operation
Vacuum operation
Single Plate Clutch
Single Plate Clutch
Basically, the clutch needs three parts.
Engine flywheel,
a pressure plate.
There are springs which provide axial force to keep the clutch in engaged position.
When the engine is running and the flywheel is rotating, the pressure plate also rotates as
the pressure plate is attached to the flywheel. The friction disc is located between the two .
When the driver has pushed down the clutch pedal the clutch is released. This action forces
the pressure plate to move away from the friction disc against the force of springs.
With this movement of pressure plate , the friction plate is released and the clutch is
disengaged.
Single Plate Clutch
Advantages
With single plate clutch , gear changing is easier than with the cone clutch ,
because the pedal movement is less in this case.
More reliable ( As it does not suffer from disadvantage of cone clutch , i.e.
binding of cones)
Disadvantages
As compared to cone clutch , springs have to be more stiff and this means
greater force required to be applied by driver while disengaging.
Multi Plate Clutch
Pressure plates
1 2 3 4 5 6
driver driven
Friction plates
Multi Plate Clutch
The multiplate clutch is an extension of single plate type where the number
of frictional and metal plates is increased.
Increase in number of friction surfaces obviously increases capacity of the
clutch to transmit torque.
Alternatively, the overall diameter of the clutch is reduced for the same
torque transmission as a single plate clutch
This type of clutch is therefore used in some heavy transport vehicles and
racing cars where high torque is to be transmitted.
This finds application in case of scooters and motorcycles, where the space
available is limited
Cone Clutch
Driven
ω shaft
Driving ω
shaft
Friction
lining
Clutch Shaft
Counter Shaft
Main Shaft
Bearings
Gears
Sliding Mesh Gear Box
Constant Mesh Gear Box
Representation of Power Transmission in Representation of Power Transmission in
First Gear Second Gear
Representation of Power Transmission in Representation of Power Transmission in
Third Gear Reverse Gear
Synchromesh Gear Box
Gears B, C, D, E attached to the main shaft A
and are free to rotate and are always in mesh
with the gears on the layshaft.
There will be no slip in the case of Synchromesh There will be the presence of slip in the case of
Gearbox Constant mesh Gearbox
The locking action was fully satisfied by Synchromesh The locking action was partially satisfied by
Gearbox Constant Mesh Gearbox
Epicyclic Gear Box
Wet Clutch
Fluid Flywheel
Torque Convertor
Torque Convertor
Automated Manual Transmission