CrankshaftThe engine's main turning shaft. The flywheel is bolted to its end.
FlywheelThe heavy wheel bolted to the crankshaft. Its rear face is one of the two surfaces the clutch disc is squeezed between.
Clutch discThe steel disc between the flywheel and the pressure plate. Its hub slides on the input shaft's splines and turns it.
Friction facingsThe friction material riveted to both sides of the clutch disc. It grips the flywheel and pressure plate, and wears as the clutch slips.
Damper springsCoil springs between the disc and its hub. They soak up the engine's shaking so it is not passed to the gearbox.
Pressure plateA heavy iron ring that the spring presses against the disc. This clamps the disc to the flywheel.
Diaphragm springA dish-shaped spring in the cover. It pushes the pressure plate against the disc; pressing its fingers lets the plate go.
Release bearingIt presses the diaphragm spring's fingers to let the clutch go. The release fork pushes it when you press the pedal. Also called the throw-out bearing.
Slave cylinderIt moves the release fork in a hydraulic clutch. Fluid from the pedal's master cylinder pushes it out.
Input shaftThe gearbox's first shaft. Its splined end fits the clutch disc's hub, so the disc turns it.
How this list was compiled: Read 2026-09-27. (1) US Army, TM 9-8000, Principles of Automotive Vehicles (1985), chapter 21 (paragraphs 21-1 to 21-4, figures 21-1 to 21-7), https://archive.org/details/tm-9-8000-principles-of-automotive-vehicles-1985 : the rear face of the engine flywheel and the pressure plate as the driving members; the clutch disk with a splined hub sliding on the clutch shaft, frictional facings riveted to each side, and compression springs between the hub and the disk to absorb torsional vibration; the diaphragm spring in the cover; the release (throwout) bearing moved by the release fork; the hydraulic system's master and slave cylinders. (2) Wikipedia, Clutch, https://en.wikipedia.org/wiki/Clutch : a friction disk pressed against the flywheel by coil springs or a diaphragm spring; the friction material of the disk; springs in some clutch disks; the release bearing; master and slave cylinders. Manual transmission, https://en.wikipedia.org/wiki/Manual_transmission : the flywheel on the crankshaft, the clutch disc between it and the pressure plate, the transmission input shaft. Licence: own work
The drawing: Drawn for this site by script, 2026-09-27. Own work, nothing traced. Licence: own work
How it works
These are the parts of a car's clutch, the single-plate dry kind in a manual car, taken apart along its shaft. The engine end is at the top and the gearbox end at the bottom.
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Engaged
The diaphragm spring pushes the pressure plate, clamping the clutch disc's friction facings against the flywheel. The disc's hub turns the gearbox input shaft, so the engine drives the gearbox. Fully engaged, the disc and flywheel turn at the same speed, with no slipping.
Pedal down
Pressing the pedal works the slave cylinder, which moves the release fork. The release bearing presses the diaphragm spring's fingers, the pressure plate lets go, and the disc stops being driven.
Throw-out bearing is another name for the release bearing, and clutch plate for the clutch disc.
Questions and answers
What are the three main parts of a clutch?
The flywheel and the pressure plate, which turn with the engine, and the clutch disc between them, which turns the gearbox. A spring clamps the three together.
What does a pressure plate do?
It presses the clutch disc against the flywheel, pushed by the diaphragm spring. When the pedal is pressed, it pulls back and frees the disc.
What wears out in a clutch?
Mainly the friction facings on the clutch disc, which wear each time the clutch slips as it takes up the drive.