What is the clutch's purpose in a car?

Answer 1

The clutch, for all intents and purposes, is a method of disengaging the powertrain(engine) from the wheels. When the clutch is engaged the power from the engine is transferred through the clutch to the wheels, so the wheels turn at the same speed as the engine (Note! This assumption is only correct when there is no gearbox or any similar equipment in the system). When you put your foot on the clutch pedal it disengages the the engine from the wheels, so that the car will freewheel like when you stop pedaling on a bicycle. Most clutches usually are friction plate clutches. A spring forces the plates together normally so that the plate on the input side of the clutch and at the output side are touching. The friction of the plate surfaces cause the two to spin together as if they were one piece. When the clutch is disengaged the two plates are forced apart. The engine side plate spins as usual but the "wheel side" slows down and eventually comes to a stop.