This standard machine screw jack has low cost, large stock and self-locking characteristics. It offers positive mechanical action, precise positioning, and uniform lifting speeds. The lifting and precisely positioning loads from 0.5 Tons to 100 Tons. A total of 10 sizes are available, each in a traveling nut version and a basic screw translating version. Operated manually or by means of gear motors, standard machine screw jacks models can be used singly, in tandem or in multiple arrangements. Under heavy load, these screw jacks are not designed for high use or heavy duty cycle applications. They also suffer from low travel rates or speed and low efficiency. However, the lack of efficiency inherent in worm gearing produces the self-locking benefit associated with worm gear screw jacks.