Unidirectional clutch

Abstract

A unidirectional clutch permits relative rotation in only one direction between a housing and a shaft that extends into the housing. The clutch includes bearings between the shaft and housing, a cylindrical friction surface on the shaft and a retainer in the housing, with the retainer surrounding the friction surface. The retainer, which is keyed to the housing and is relatively long, has pockets which open toward the friction surface. Each pocket is in part defined by a ramp which lies oblique to the friction surface, giving the pocket a large region and a small region. Each pocket contains a roller which is small enough to fit loosely in the large region and too large to fit into the small end. At each end of the retainer channels open laterally, and these channels contain pistons and springs, with the latter urging the former against the rollers in the pockets to urge the rollers toward the small regions of the pockets. End rings fit against the ends of the retainer and close the pockets to capture the rollers and likewise close the channels to hold the pistons and springs in place. The clutch permits relative rotation between the shaft and housing in the direction which tends to drag the rollers toward the large regions of the pockets, but in the reverse direction the rollers lodge between the retainer and the friction surface and transfer torque between the housing and shaft.