A worm gear ball screw jack is a high-efficiency mechanical actuator that combines a worm gear reduction set with a precision ball screw and ball nut. Unlike standard machine screw jacks that use sliding friction, these units utilize rolling friction via ball bearings, significantly increasing efficiency and allowing for higher speeds and duty cycles. These ball jacks are high-efficiency actuators capable of lifting and precisely positioning loads typically ranging from 1tons to 50tons (approx. 500 kN) as standard. Due to their low internal friction, ball screw jacks will "back-drive" under load. They require a brake motor or an external locking device to hold their position. They are typically 90% to 95% efficient, compared to only 30% to 40% for machine screw jacks. They require approximately one-third to two-thirds less input torque to move the same load, allowing for the use of smaller motors. These units are generally more expensive than machine screw jacks due to the precision-engineered ball nut and screw components.