The clutch system is made up of the clutch disc, flywheel, pressure plate, throw-out bearing, pilot bearing, and clutch fork. The flywheel and pressure plate are bolted together and both are attached to the crankshaft of the engine. The clutch disc is located in between the flywheel and pressure plate and is connected to the splined input shaft of the transmission. The clutch disc has a friction surface on each face that comes in contact with the smooth surfaces of the flywheel and pressure plate.
When there is no pressure on the clutch pedal, springs inside the pressure plate clamp the clutch disc between the pressure plate and flywheel, and all three pieces spin together. When the clutch pedal is pushed down, the clamping force from the pressure plate is relieved and the clutch disc spins independent of the flywheel and pressure plate. This allows the vehicle to stop with the engine running and allows the vehicle to change gears.
What happens when a clutch wears out.
The friction material on the clutch eventually wears out, so that the pressure plate will not be able to put sufficient pressure on the clutch disc to keep it from slipping. A slipping clutch is first noticed when accelerating in a high gear: engine speed will raise without a change in vehicle speed. As the clutch deteriorates more and more, the vehicle will reach a point where it will not move at all.
At this time, the transmission must be removed in order to replace the clutch disc and pressure plate. The flywheel should also be replaced or resurfaced at this time to prevent judder and accelerated clutch wear. If the vehicle uses a dual-mass flywheel, this part should be replaced as part of the clutch service.
The clutch system determines when to send power to the transmission.
When the clutch pedal is depressed, the clutch disc is disengaged, allowing the engine to run without turning the transmission.