Clutch

A clutch is a mechanical device that connects and disconnects the powertrain from the driving wheels. In vehicles with manual transmissions, it allows the engine to run while the car is stationary and enables smooth torque transfer during gear changes. The core components are a clutch disc (friction plate) pressed against a flywheel by a pressure plate, with a release bearing that disengages the clutch when actuated. The clutch is typically operated by a pedal in manual cars, and by hydraulic or cable actuation in other setups. When the pedal is pressed, the release bearing moves the pressure plate away from the clutch disc, breaking contact and allowing the gears to change.

Friction clutches transmit torque by contact between the clutch disc and flywheel. Configurations include single-plate and multi-plate designs, and they may be dry or lubricated (wet). In manual transmissions, the clutch is used to disengage the engine during shifting and to permit smooth engagement. Automatic transmissions use a torque converter to provide a fluid coupling, while some modern automatics use wet multi-plate clutches within the gear train, controlled by a computer.

Outside vehicles, "clutch" has other meanings. A clutch bag is a small, handheld handbag, typically without handles, used for formal occasions. A clutch of eggs refers to a group laid by a female animal, especially birds. The verb "to clutch" means to grasp something tightly, and the phrase "in the clutch" describes performing well under pressure.

Clutch is also used figuratively to denote a decisive action or contribution at a critical moment, such as a clutch performance in sports or games. The term's usage spans engineering, fashion, and everyday language, with the common thread being a moment of connection, grasp, or decisive transfer of control.