Widely used in car is in spring tightly (hereinafter referred to as the friction clutch friction clutch). Active part of the clutch and driven by the friction between the surface part, or use liquid as transmission medium (hydraulic coupling), or a magnetic transmission (A/C electromagnetic clutch) to transfer torque, temporarily separation between the two, and gradually in the course of transmission, and allow the two parts interaction.

Friction clutch should meet the following basic requirements:

(1) effortless manipulation, maintenance is convenient main reducer.

(2) with ease, the direction of rotation direction of vibration attenuation capability, and little noise.

(3) can make, and separated when jointing, and has good downy heat-radiating capability.

(4) as part of a follower of inertia. So, in the separation, and the shifting clutch input shaft transmission speed is connected to the easy part, and reducing the impact between gear.

(5) pressure plate stress and the friction coefficient of variation, steady job. To ensure maximum transmission of engine torque, and certain transmission torque force.

(6) engine torque, issued by the flywheel and pressure plate and the friction surface platen, pass driven plate. When the driver pressed the clutch pedal, through the transmission mechanism, make the diaphragm spring main drive back platen, driven and separation.