Hydraulic release systems give greater flexibility than cable or mechanical mechanisms. The master cylinder is mounted on the firewall or can be incorporated in the pedal and is connected to the slave cylinder via a flexible hose. Flexible hoses are used to accommodate any relative movement between the body and engine/transmission. The concentric slave cylinder eliminates the need for a clutch release lever by combining the release bearing and slave cylinder on the gear box front bearing retainer. As the friction material on the driven disc wears, the release mechanism is repositioned forcing the excess fluid to the master cylinder reservoir. By design, the efficiency of the release system is achieved by a small bore diameter master cylinder with a larger bore slave cylinder.
There are two types of master cylinder:
1. Compensating Port Design
2. Centre Valve Design
Clutch Master Cylinders