Clutch Master Cylinder

WARNING: This page is about a different variant/trim than selected.

Courtesy of FORD MOTOR COMPANY

Item	Description
1	Breather hole
2	Replenishing hole
3	Depressurized space
4	Pistons
5	Replenishing valve
6	Pressure chamber

Function

The master cylinder is responsible for generating the fluid pressure for the hydraulic system.

When the piston is in the rest position, the volume in the pressure chamber and the reservoir is equalized via the compensating bore. When the piston moves over the compensating bore, fluid pressure builds up in the pressure chamber.

Operation

The hydraulic fluid is extracted from the brake fluid reservoir. This line ends in the clutch master cylinder. Due to the different piston diameters, a gear ratio can be set that reduces the pedal forces, e.g. when the diameter of the clutch master cylinder is smaller.

Clutch release bearings must withstand large axial forces. Previously, during normal driving, low play brought the vehicle to a stop when the clutch pedal was not actuated. The release bearing only rotated during engagement of a gear. Due to better protection against wear, current clutch release bearings always rotate. With hydraulic clutch actuation, the clutch slave cylinder can be integrated centrally in the clutch release bearing.

NOTE: Long actuation of the clutch, e.g. at a red traffic light, creates an unnecessary load on the clutch release bearing, the clutch disc and the axial bearing of the crankshaft.