Classic Ball Screw Jack is also called Mechanical Worm Gear Ball Screw Jack. Lift and Position loads from 1 Ton to 35 Ton. Why choose ball screw jacks, but not machine screw jacks? because of the higher speeds, higher duty cycles and higher efficiency of the ball screw (compared to a machine screw) ball screw jacks can decrease 70% motor horsepower and other electrical requirements.