The clutch actuation system is installed in automobiles and comprises 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 passenger car clutch actuation systems.

Concentric slave cylinder (CSC)

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

This is advantageous compared to conventional release systems: 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 also offers clutch kits with CSC.

Concentric Slave Cylinder (CSC)

Concentric slave cylinder csc Concentric Slave Cylinder (CSC)

Function of a hydraulic release 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. A preload generated by the actuation system ensures that the clutch and the release bearing thrust ring are running at the same speed. Speed differences would lead to the generation of noises 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.

Concentric slave cylinder (CSC)

Master and slave cylinders

The clutch actuation system 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 clutch release bearing and lever.

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

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

Function of the master/slave cylinder

The clutch actuation is transferred hydraulically in systems equipped with a master/slave cylinder. 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 high mechanical stress. The first indications of wear are increased physical effort and noises when actuating the clutch, or clutch slipping and grab.

SACHS clutch cables

SACHS clutch cables SACHS clutch cables

Function of the 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 actuated. The highlighted areas show wearing zones in the clutch environment.

Clutch actuation system with cable control