A device with one or more actuator racks carried by a housing for reciprocation and each meshing with a separate pinion gear having a non-circular central hole in which a complimentary coupling shaft can be removably received for rotation in unison with the gear(s). The pinion gears are carried and journalled for rotation in the housing by a pair of co-axial bushings with generally opposed and spaced apart axially projecting rims received in mating peripheral shoulders in the side faces of the gears. The gear teeth extend generally axially continuously between their side faces with the shoulders in their side edges. Preferably the radial extent of each shoulder is less than the radial extent of the teeth. When the coupling shaft is removed from the gears each pinion can rotate independently of the shaft and each other to initially position its associated rack at a desired location and when the shaft is inserted in the pinion gears they rotate in unison to simultaneously actuate the rack(s).
