Screw Jacks are found wherever there is a need to lift, position and hold load. A Screw Jack (also known as a Jack Screw, a Worm Screw Jack, a Machine Screw Jack or a Lead Screw Jack) is a devise used to convert rotational motion into linear motion.
Worm Drives are used when the axis of rotation of a shaft must change direction. Being low-cost, potentially self-locking and providing high gear reductions, Worm Drives provide an effective means of decreasing speed whilst increasing torque.
Mechanical screw jacks and linear actuators are increasingly becoming the preferred choice of actuation over the equivalent hydraulic or pneumatic systems.