Transmission is the mechanism which is used to transfer the power developed by engine to the wheels of an automobile. The transmission system of an automobile includes clutch, gear box, propeller shaft axle and wheels, etc.
Description of various types of clutches and gear boxes has been given in the following sections of this unit. The term ‘Transmission’ is used for a device which is located between clutch and propeller shaft. It may be a gear box, an over drive or a torque converter, etc.


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 examples and its parts
Clutch Parts
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.

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.

It consists of
(a) a driving member,
  •  The driving members consists of a flywheel which is mounted on the engine crankshaft
  • The flywheel is bolted to a cover which carries pressure plate, pressure springs and releasing levers.
  • As the flywheel is bolted to the cover assembly, thus, the entire assembly of the flywheel and the cover rotate all the times.
  • The clutch housing and cover provided with openings so that the heat produced during the function dissipates easily
(b) a driven member, and
  • The driven members consists of a disc or plate called clutch plate.
  • The clutch is free to slide on the splines of the clutch shaft.
  • It carries friction materials on both of its surfaces.
  • When the clutch plate is gripped between the flywheel and the pressure plate, it rotates the clutch shaft through splines.
(c) an operating member.

parts of clutch
Parts Of Clutch
The operating member consists of a pedal or lever which can be pressed to disengaged the driving and driven plate.

Function And Requirement Of Clutches:

Function and Requirement Of Automobile Clutches | Types Of Clutches

Some types of clutches used in vehicles are given below :
(a) Friction Clutch : It may be (i) single plate clutch, (ii) multi-plate clutch, or (iii) cone clutch. Multi-plate clutch can be either wet or dry. A wet clutch is operated in an oil batch whereas a dry clutch does not use oil.
(b) Centrifugal clutch.
(c) Semi-centrifugal clutch.
(d) Hydraulic clutch.
(e) Positive clutch.
(f) Vacuum clutch.
(g) Electromagnetic clutch.
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