Clutch Slave Cylinder: Description and Operation

The slave cylinder is an annular hydraulic cylinder which is mounted in the flywheel housing and is designed so that the clutch shaft passes through it. The slave cylinder consists of an outer cylinder housing and an internal sleeve, with an annular piston and a lip seal arranged between them. The release bearing is secured to the piston with a circlip and is sealed with an 0-ring. When the clutch pedal is depressed, the slave cylinder piston and release bearing will move towards the diaphragm spring. When the pedal is released, the release bearing and piston will be returned by the diaphragm spring. Further return movement of the piston is prevented by the friction of the lip seal in the slave cylinder and by the friction of the dust cover against the slave cylinder housing. As a result, the release bearing is almost in contact with the diaphragm spring when the clutch pedal is released. Adjustment of the clutch is carried out automatically by the dust cover moving as the clutch lining wears.

SLAVE CYLINDER OF MODIFIED DESIGN
The clutch slave cylinder is of modified design as from the following chassis numbers: 90 80 101 8583 and 90 80 200 5638
The slave cylinder piston was equipped with a movable locking ring, the function of which was to prevent excessive return travel. This has been replaced by a plastic sleeve with a circlip, operating against a turned surface on the slave cylinder housing. The plastic sleeve also serves as a dust cover for the slave cylinder.
The new slave cylinder piston replaces the earlier piston as a spare part, together with new hexagon socket-head securing screws.





EARLIER VERSION OF SLAVE CYLINDER
1. Slave cylinder housing
2. Sleeve
3. Piston
4. Lip seal
5. 0-ring
6. Release bearing
7. 0-ring
8. Circlip
9. Locking ring

LATER VERSION OF SLAVE CYLINDER
1. Slave cylinder housing
2. Sleeve
3. Piston
4. Lip seal
5. 0-ring
6. Release bearing
7. 0-ring
8. Circlip
9. Plastic sleeve with circlip