1/4-to-250-ton capacity. Anti-backlash actuators reduce vertical backlash resulting in smooth, precise operation and minimal wear. Backlash occurs when the motor driving an actuator reverses its load direction. When the actuator is under load, the lifting screws threads are supported by the worm gears threads. The anti-backlash nut, pinned by the worm gear and adjusted downwards by the shell cap, forces the bottom thread surfaces against the upper thread surfaces of the lifting screw. Thus, backlash between the lifting screw and worm gear threads is reduced to a minimum.