The Function of a Slave Cylinder
All manual transmissions come fitted with a clutch, which is a disc covered in a friction-resistant material. This disc contacts the metal f...

All manual transmissions come fitted with a clutch, which is a disc covered in a friction-resistant material. This disc contacts the metal flywheel on the rear of the engine and transfers the rotation energy from the engine to the transmission. In early years, a cable engaged and disengaged the clutch and needed periodic adjustment. A hydraulic component, known as the slave cylinder, eliminates the need for adjustment by using fluid to engage and disengage the clutch.
Function of the Slave Cylinder
The slave cylinder is a small, hydraulic cylinder mounted inside or outside of the transmission. When you press the clutch pedal, brake fluid presses the slave cylinder's piston outward against the clutch fork or the pressure plate. The clutch then separates from the engine flywheel, stopping the transfer of energy from the engine to the transmission.
Fluid Supply
The slave cylinder receives its fluid from either the clutch master cylinder or the brake master cylinder, depending on the vehicle. No matter where the fluid comes from, the clutch master cylinder uses the same fluid as the brake system.
Bleeding
Bleeding the slave cylinder purges all of the air from the slave cylinder and the clutch lines. This process is required after replacing the slave cylinder and can rectify a spongy clutch pedal issue.