A screw is a mechanical system that converts rotational motion in to linear motion. In other worlds it converts rotational force (torque ) in to a linear force. Here the resultant axial force due to an input torque is calculated from first principles.
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.
Mechanical screw jacks and linear actuators are increasingly becoming the preferred choice of actuation over the equivalent hydraulic or pneumatic systems.