Valeoscope Commercial Vehicles Clutch 2020

Valeo clutch and actuation for heavy duty

1.4 Clutch disc The clutch disc is a part linked to the primary shaft of the gearbox and fitted between the flywheel and the cover assembly. It allows to damp out the vibrations coming from the engine and to transmit progressively the torque to the gearbox.

The characteristics of each clutch disc are designed following the driveline on which it has to be fitted. On modern products, a second damper, called pre- damper, is used to avoid noises coming from the gearbox syncromeshs and gearbox chattering when the vehicle is in neutral at idle speed. This damper is located between the main damper and the hub. Its filtering capacity is lower than the main one. Cushion disc: This system has an undulating surface which provides a spring characteristic during clutch engagement and disengagement phases. It is located between the two facings and allows a progressive torque transmission, for the driver comfort. 1. Disc in declutch position (No diaphragm effort) 2. Compression of the set (disc+facings) by the diaphragm effort 3. Full compression of the set (disc+facings) by the maximum diaphragm effort Advantages of cushion: ●● The pressure plate is subjected to high thermal changes. In hot conditions, it has a convex shape while a concave one in cold conditions. Thanks to the cushion disc, the facing remains in full surface contact with the pressure plate whatever its deformation, in normal working conditions. Without cushion disc, the clutch engagement is jarring and uncomfortable for the driver and can generate clutch slippage. ●● Reducing judder. Twin disc clutch Twin disc clutch kit consists of a clutch cover, two clutch discs, an intermediary pressure plate and a release bearing. Valeo already launched several part numbers for some Mercedes-Benz, Renault-Trucks MAN and Volvo applications.

Guide washer

Disc (Cushion)

Rivet (disc)

Spring

Hub

Pre-damper

Load

1

3

Spring (pre-damper)

Steel backing

2

2

Facing

Flenge

Friction washer

1

3

The clutch disc is composed of: • a splined hub for the fitting on the primary shaft • a metallic part, on which two facings are riveted. On modern applications, the clutch disc is designed with a damper to absorb vibrations from the engine and with a cushion disc to allow a smooth clutch engagement and a 100% torque transmission. Damper working principle In different parts of the transmission, filtrating vibrations coming from the engine is an important and a difficult issue. To do this very important operation, a damper is fitted between the facings (linked to the engine) and the hub (linked to the gearbox primary shaft). During the running of the vehicle, the damper, thanks to its angular deflection, will absorb the engine vibrations and the torque variations due to gear shiftings and accelerations/decelerations of the vehicle.

Clutch disc

Disc thickness under maximum diaphragm effort

Displacement

8

9