Ambreiaj

Ambreiaj, or clutch, is a mechanical device that connects and disconnects the engine from the drivetrain in manual and some automated transmissions. Its primary purpose is to enable gear changes and to permit the engine to run without driving the wheels, such as when starting from a stop or when shifting gears.

A typical clutch assembly includes a flywheel attached to the engine, a pressure plate, a clutch disc with friction material, and a release mechanism such as a throw-out (release) bearing. The pedal, actuated by the driver, moves the release bearing against the pressure plate springs. Pressing the pedal reduces the clamping force, allowing the disc to slip away from the flywheel and disconnect power. Releasing the pedal restores clamping, re-engaging the engine with the transmission.

Clutch types vary by design and application. Dry single-plate clutches are common in manual transmissions. Dry multi-plate clutches are used in some high-load or performance applications. Wet clutches are immersed in oil and are used in motorcycles and in many automatic or automated manual transmissions; they are generally cooler and longer-lasting. Actuation can be hydraulic (master and slave cylinders) or mechanical (cable). Dual-clutch transmissions employ two separate clutches controlled by electronics, enabling rapid gear changes.

Wear and maintenance are important considerations. Clutches wear gradually, with symptoms such as slipping, chatter or vibration during engagement, difficulty selecting gears, or a high pedal bite. Replacement typically involves the friction disc, pressure plate, and release bearing, and life depends on driving style, conditions, and whether the clutch is wet or dry. Proper lubrication and avoiding oil contamination are essential for some designs.

Modern vehicles rely on the ambreiaj for smooth starts, controlled deceleration, and precise gear changes, while advances focus on reducing pedal effort, heat buildup, and improving durability.