Clutch Actuation System Car

Clutch actuation systems for passenger cars and clutch actuation systems for LCV are installed in automobiles and comprise all components with which the power is transferred from the pedal to the clutch release bearing in order to release the clutch. The pedal travel is transferred mechanically (usually via a cable pull) or hydraulically. SACHS supplies various types of actuators and clutch actuation systems.

Concentric slave cylinder (CSC)

The concentric slave cylinder (CSC) combines the clutch release bearing and the slave cylinder to an integrated unit. As a result, the release fork between the clutch release bearing and the slave cylinder as well as the respective bearing points are not required. Assembly takes place directly on the transmission.

This is advantageous compared to conventional clutch actuation systems for cars: Vibrations and grabs during launch are prevented as the number of mechanical components has been reduced. The driver benefits from the best possible ride comfort.

The concentric slave cylinder (CSC) should be replaced with each clutch repair in order to prevent delayed signs of wear and, consequently, further repairs.

As concentric slave cylinders are now installed as standard in approximately half of all vehicle models, SACHS automotive products also contain clutch kits with CSC.

Further information on SACHS clutch kits

Concentric Slave Cylinder (CSC)

Function of a hydraulic clutch actuation system with CSC

The concentric slave cylinder (CSC) (1) is assembled directly on the transmission.

The diaphragm-spring clutch can be set free of clearance, i.e., the release bearing is constantly running whilst the clutch is turning. An initial load generated by the clutch actuation system for passenger cars and LCV ensures that the clutch and the release bearing thrust ring are running at the same speed. Speed differences would lead to the creation of noise and increased wear.

The release bearings are self-centering (can be radially adjusted by approx. 1.5 mm), in order to compensate for alignment tolerances between the diaphragm spring and the clutch release bearing thrust face. They centrically adjust to the diaphragm spring tongues automatically during the first clutch actuations.

CSC clutch release bearings are used when the installation space is not large enough for a conventional clutch actuation system.

Hydraulic clutch actuation system with CSC

Master and slave cylinders

The clutch actuation system for cars transfers the pressure of the driver’s foot on the pedal to the clutch in order to disengage it. It has to ensure absolute reliability, meet ergonomic requirements and provide a high level of comfort throughout its entire service life. The actuation system includes the hydraulic transmission path with master and slave cylinder as well as the mechanical part with the clutch release bearing and the lever.

SACHS master cylinder (left) and slave cylinder (right)

Function of the master/slave cylinder

In systems equipped with a master/slave cylinder the clutch actuation system for cars and LCV is transferred hydraulically. The pedal motion is transferred to a hydraulic cylinder (1, master) located directly below the pedal. In a closed system, the cylinder generates hydraulic pressure that is absorbed by a slave cylinder (3) via a hose assembly (2).

In order to ensure ideal functionality, it is possible to bleed the clutch actuation system.

Conventional master/slave cylinder

High-quality SACHS clutch cables

With its high-quality clutch cables, SACHS covers the European vehicle market almost completely. Clutch cables are subject to a high level of mechanical load. The first indications of wear are increased physical effort and noises when operating the clutch, or clutch slipping and grab.

SACHS clutch cables

Function of the mechanical clutch actuation system with cable control

The clutch actuation is transferred purely mechanically via clutch cables. The pedal motion is transferred to a steel cable (1), the release fork (2) and the clutch release bearing (3) so that the clutch is operated. The highlighted areas show wearing zones in the clutch environment.