Clutch

A clutch consists of a friction disc, a pressure plate and a release bearing. Most modern clutches are operated hydraulically by the pedal. Dual-clutch gearboxes use two clutches controlled automatically. The release bearing (thrust bearing) presses on the pressure plate’s diaphragm spring. In hydraulic systems, a master cylinder at the pedal and a slave cylinder at the gearbox move it.

Springs in the pressure plate clamp the friction disc against the flywheel. Pressing the pedal pulls the springs back, releasing the disc so the engine and gearbox can turn at different speeds.

A worn clutch slips, burns and engages higher on the pedal. Riding the clutch and frequent hard starts shorten its life. A clutch is normally replaced as a kit: disc, pressure plate and release bearing. Some cars need a relearn of the clutch position after replacement.