Machine Screw Jack is devided into worm gear machine screw jack (standard & square types) and bevel gear machine screw jack. Most higher ratio machine screw jacks are self-locking and will hold heavy loads indefinitely without creeping. However, if self-locking is absolutely necessary, a motor brake or other restraining device should be considered. They can be used to push, pull and apply pressure and position precisely. Operated manually or with air, hydraulic or electric motors, machine screw jacks can be used individually, in tandem or in multiple arrangements.