A throw-out bearing, also called a clutch-release bearing, works by pushing on the springs of the clutch cover plate. These springs hold the clutch friction plate against the flywheel. This has the effect of releasing the drive from the engine through the gearbox.
The throw-out bearing is activated when the clutch pedal is depressed and the clutch cable pulls against the release lever, pushing the bearing against the springs. When the clutch is depressed, a chirping noise can be a sign of a throw-out bearing starting to fail. A replacement clutch kit contains a friction plate, throw-out bearing and cover plate.