Sprag Clutch is a one-way freewheel clutch. It resembles a roller bearing, but instead of cylindrical rollers, non-revolving asymmetric figure-of-eight shaped sprags are used. When the unit rotates in one direction the rollers slip or free-wheel, but when a torque is applied in the opposite direction, the rollers tilt slightly, producing a wedging action and binding because of friction. The sprags are spring-loaded so that they lock with very little backlash.

Applications: Automatic transmissions, Helicopters, Motorcycle, Starters, Primary drive, Conveyors, Overrunning, Indexing, Backstopping, Hoist load brake.