The common hydraulic jack uses this principle to achieve force transmission. The screw jack pulls the handle in a reciprocating manner. Pulling the pawl pushes the ratchet clearance to rotate. The small bevel gear drives the large bevel gear to rotate the lifting screw, so that the lifting sleeve can be lifted or lowered to achieve the function of lifting tension, but it is not as simple as the hydraulic jack.

Jack is divided into mechanical jack and hydraulic jack, and the principle is different. In principle, the most basic principle that hydraulic transmission is based on is Pascal's law, that is, the pressure of liquid is consistent everywhere. In this way, in a balanced system, the pressure exerted on a smaller piston is smaller, while the pressure exerted on a larger piston is larger, so that the liquid can be kept still.