The internal part of the screw jack is composed of three main parts: worm wheel, worm gear, and screw. The rotation of the worm gear drives the rotation of the worm wheel, which in turn drives the movement of the screw, and can be driven directly by the motor or other power, or manually.
The screw jack can be divided into A-type and B-type according to the assembly form. The screw (or nut) moving up is type A, and the screw or (nut) moving down is type B. The screw jack can be divided into type I and type II according to the structure form. The screw does axial movement is a type I. The screw does rotational movement and the nut does the axial movement in type II.
The head form of the screw can be divided into I and II type, and the head structure of the I type screw jack is divided into cylindrical type, flange type, threaded type, and flathead type.
The protection of the screw can also be divided into different types according to I and II types. I type has basic type and type with dust cover. Type II has the basic type and the type with dust cover.