Cam 1 turns about fixed axis A. Lever 2 turns about fixed axis B and carries pawl 3 which contacts cam 1. When cam 1 is turned counterclockwise, lever 2 turns clockwise until pawl 3 slips off cam 1 and lever 2 is returned by spring 6 against stop 5. At this, a spring (not shown), connected to lever 2, operates the stamp of the time clock. When the handle of the clock is released, spring 7 turns cam 1 clockwise, and pawl 3 turns about axis C to allow cam 1 to pass by so that all the links are again in the initial position.