Sprag clutch

[1] A sprag clutch is used in many helicopter designs to transfer power from the engine to the main rotor.

Many modern sport and racing motorcycles use sprag clutches in the primary drive between the engine and transmission.

If a sprag clutch is not present, much greater care is required when downshifting, because losing rear wheel traction can cause dangerous highside accidents.

The reciprocating motion of the prime mover is converted to an indexing movement on the other race of the sprag clutch.

Backstopping prevents a loaded inclined conveyor from running back when the drive system is stopped.

The outer race of the sprag clutch is fixed to the machine frame, usually via a torque arm.

A sprag clutch is used in some pumping systems where a standby prime mover is required in case of a failure by the main drive.

An example is a pump with a single rotating shaft through the unit connected at one end by an electric motor and the other by a standby diesel engine isolated by a sprag clutch.