US Patent 7607370 Crank with clutch and coupler

A crank including a mechanism capable of connecting the crank arm to a shaft to drive the shaft in rotation in either a unidirectional drive mode or a bidirectionally driving mode, the mechanism being quickly adjustable between modes. A coupler in the mechanism may be slidable between a first position engaging the crank arm with a hub portion fixedly mounted on the shaft and a second position in which a unidirectional clutch can operate to allow rotation of the crank arm freely about the shaft in one direction but cause rotation of the shaft in the opposition direction. The coupler may be arranged to be coupled only when the shaft is in a selected angular position.