One-way clutch

A one-way clutch (freewheel) transmits torque in one direction of rotation and overruns freely in the other. Locking is achieved by sprags or rollers that wedge between inner and outer ring in the driving direction. Three basic functions cover most applications: backstops prevent reverse rotation, for example on inclined conveyors; overrunning clutches disengage a drive automatically when the driven side rotates faster; indexing freewheels convert oscillating motion into stepwise rotation. Designs range from clutch-only units without bearing support to complete ball-bearing-supported freewheels and sprag cages for customer-supplied rings. Torque, overrunning speed and suitable lubrication govern selection.