Square Ball Screw Jacks incorporate a ball screw instead of a machined screw and a ball nut, which activates the screw. These units feature a compact and versatile square housing (machined on all sides). Ball screw versions for faster speeds and lower torques. Maximum lifting capabilities range from 10kN to 300kN. The advantage of ball screw jacks and the rolling action of their design is greater efficiency, up to 50%. Because of their efficiency ball screw jacks can be used in heavier duty cycle applications. They also provide good positional accuracy in high speed applications. One potential disadvantage is that ball screw jacks are not self-locking and will require a brake or motor with enough holding torque to prevent the input shaft(worm) from back-driving.