A clutch is a mechanical device that connects and disconnects the output shaft from the rotating input shaft. It is typically used in motor vehicles as a mechanical linkage between the engine and transmission. The clutch allows the engine speed (RPM) to be disengaged from the speed of the driven wheels, which is necessary for changing gears in a manual transmission car. The clutch is connected to both the shaft coming from the engine and the shafts going to the wheels. When the clutch is engaged, the wheels are connected to the engine and rotate at the same speed as the engine. When the clutch is disengaged, the wheels are disconnected from the engine and can stop moving without killing the engine.
The clutch is also used in other devices, such as electric drills, where it allows the drill bit to spin at the same speed as the motor (clutch engaged), spin at a lower speed than the motor (clutch slipping), or remain stationary while the motor is spinning (clutch disengaged) . Clutches can be dry or wet, with dry clutches using dry friction to transfer power from the input shaft to the output shaft.
