What does a clutch disc consist of?

The clutch plate, also called clutch disc, is crucial in manual transmission vehicles. It transfers power from the engine to the transmission, enabling smooth engagement and disengagement for gear changes. It allows controlled slippage, adjusts torque transmission, and protects drivetrain components by absorbing shock and vibrations.

 

The clutch disc is round and constructed of thin, high quality steel with a splined (grooved) hub placed in the center. The hub splines engage splines on the transmission input shaft. The clutch disc can move back and forth on the shaft, but when the disc is turned, the shaft must turn also.

Both sides of its outer edge are covered with friction material that sandwhiched between the flywheel and the pressure plate.It is often made of asbestos or other high temperature material and copper wires either woven or molded together. It is riveted to the disc.

To assist in smooth engagement, the disc outer edges are often split and each piece cupped.The friction material is riveted to these segments. When the disc is compressed, these cupped segments act as a spring-like cushion.

                                                                                                       

A clutch disc mainly consists of following components:

Facing: The surface of the disc that comes into contact with the pressure plate and flywheel. It needs to be durable and resistant to wear. Most facing plates are made of asbestos-based materials, and their size is mainly determined based on the type of the vehicle and the engine torque transmitted.

Damper Springs: These are often embedded within the friction material or attached to the hub to absorb shock and dampen vibrations during engagement. The radius of the shock absorbing spring distribution should be as large as possible, and the number should be selected according to the outer diameter of the friction plate.

Diameter of the facing D/mm	Number of the springs
225~250	4~6
250~325	6~8
325~350	8~10
>350	More than 10

 

Hub: The center part of the disc that connects to the transmission input shaft.

                                                                                                              

Splines: Grooves or teeth around the center hole that mesh with the transmission input shaft, allowing the disc to transfer torque. The structural size of the spline is determined by the outer diameter of the driven plate and the engine torque, according to the GB1144~1974 standard.

For example:

Dimater of clutch disc D/mm	Engine Torque Te/N·m	Number of teeth n	Outer diameter of splines D'/mm	Inner diameter of splines d'/mm	Thickness of teeth b/mm
160	50	10	23	18	3
180	70	10	26	21	3
200	110	10	29	23	4
225	150	10	32	26	4
250	200	10	35	28	4
280	280	10	35	32	4
300	310	10	40	32	5
350	480	10	40	32	5
380	600	10	40	32	5
410	720	10	45	36	5
430	800	10	45	36	5
450	950	10	52	41	6

 

Plate: Usually made of organic, ceramic, or semi-metallic materials, this is the part that makes contact with the flywheel and pressure plate to transmit power. It is riveted together with the cupped segments to make the pressure distribution more even, which is beneficial to the uniform wear of the friction plate.

Clutch disc is essential for the proper functioning of a manual transmission vehicle, enabling smooth and efficient power transfer while providing control and protection for the drivetrain components.