A power door-lock actuator has a housing adjacent the lock, a reversible electric motor in the housing having an output shaft extending along a motor axis, and an input gear fixed on the output shaft and rotatable thereby about the motor axis. A threaded spindle extending in the housing along a spindle axis adjacent the motor axis carries an output gear and a nut threaded on the spindle is movable along the spindle axis on rotation of the spindle between a pair of axially offset positions. A link connected between the nut and the lock can move the lock between its locked and unlocked positions on displacement of the nut between its end positions. A manual actuator, for instance an inside door-lock button, is coupled to the nut for manually displacing the nut between its end positions. A rocker pivotal about the shaft axia at the input gear carries a pair of connecting gears flanking and meshing with the input gear. This rocker is pivotal between angled positions in each of which a respective one of the connecting gears meshes with the output gear and through a central position with neither of the connecting gears meshing with the output gear. A spring urges the rocker into the central position so that torque transmitted to the rocker on rotation of the input gear pivots the rocker depending on input-gear rotation direction into one of its angled positions to couple the input gear to the output gear.