Clutch Glossary of Terms

Bob Deierlein

Bearing Gap: Space between the release bearing and the clutch brake.

Clutch Brake Squeeze: Distance the pedal moves as the load is applied to the clutch brake.

Clutch Lever Ratio: An internal ratio for the clutch of the clamp load applied to the driven discs, divided by the maximum load at the release bearing required to release the clutch.

Clutch Torque: The clutch torque rating, normally calculated as a static condition.

Free Pedal Travel: Pedal travel as the release fork tips travel through the yoke gap.

Peak Engine Torque (T): The maximum gross torque of the engine.

Pedal Stroke: Full movement of the pedal, from the top of the stroke to, and including, the clutch, transmission, driveline, axle and tires.

Release Bearing Travel: Distance the release bearing moves during the release of the clutch.

Release Pedal Travel: Distance the pedal moves during release bearing travel.

Startability: Ability to start the vehicle with the engine idle.

Soft-Damped Clutch: Assemblies using soft-rate damped driven disc assemblies.

Soft-Damped Driven Disc Assemblies: Driven discs designed to transfer the engine torque to the transmission at a low rate compared to older designs or rigid hub-driven discs. All U.S. clutch manufacturers have trade names for these soft-damped driven discs, such as GD, Seven Spring, VCT or LTD.

Yoke Gap: Space between the yoke fingers and the clutch release bearing.