Role of clutch
1. ensure the car a smooth start: before starting the car at rest if the engine and transmission are rigid, once hung on, auto connect the sudden power suddenly thrust will not only cause mechanical damage, and driving force was not enough to overcome the tremendous inertia forward cars, sharp decline in the speed of the engine flameout. If the clutch when starting to separate the engine and transmission for the time being, and then gradually engage clutch due to clutch the active part and there is friction between moving parts, you can make out of clutch torque increases from zero, increasing while the driver of the car, giving the car a smooth start.
2. ease of shifting: a car while, often using different gear, to adapt to changing road conditions. If there is no clutch to separate the engine and transmission for the time being, the gear meshing force in gear will load without dismounting, the meshing tooth surface is very stressful and difficult to separate. Other treat gear for circumferential speeds ranging between them to mesh. Even forcibly entered the engagement will have a great deal of tooth impact and easily damaged parts. Clutch the engine and gearbox is temporarily separated after the shift, the meshing of the gear pair load is removed, pressure greatly decreases between the mating surface, it is easy to separate. Another pair of gears to be meshing, due to the drive gear and the engine separated the moment of inertia is small, right shift movements will be meshing gear rate equal or close to equal, so as to avoid or mitigate the impact of gear.
3. Prevention of transmission system overload: automobile emergency brake, wheel suddenly slow down, regardless of the transmission due to the rotation of the engine's inertia, still keep their original speed, which tend to produce much more than engine torque in the transmission system of the moment of inertia, driveline parts easily damaged. Because is depends on friction torque of the clutch, so when the drive loads over friction within the transmissible torque, clutch master, slave part automatically slip, which played a role in preventing transmission system overload.
4. reduce the torsional impact: principle determines the output torque of the engine is not smooth. During the power stroke, the combustion chamber gas explosions have a great impact torque, and other stroke, it is anti-dragged by inertia motors. Inertia of the rotating frame, the engine itself is to reduce torsional vibration, but the residual impact continued to adversely affect subsequent transmission, drive shaft. The vibration in the clutch springs (tangential) and can significantly reduce the impact torsional vibration of the engine and extend gear life.