The 50-ton screw jack is widely used in industry and construction. The specification of 50 tons is a larger specification in the screw jack, because the screw jack is driven by human power. Screw jack belongs to a kind of hoisting machinery. According to the principle of screw transmission, the screw pair composed of screw and nut is used to realize transmission. Convert rotary motion into linear motion and transmit motion and power. So as to lift the object to a certain height. It is a simple lifting equipment with a height less than 1 meter. It has the advantages of compact structure, uniform, stable and accurate rotation and easy self-locking.