Jacks are divided into mechanical jacks and hydraulic jacks, each with different principles. In principle, the most basic principle on which hydraulic transmission is based is Pascal's law, which means that the pressure of the liquid is consistent everywhere. In this way, in a balanced system, the pressure applied on the smaller piston is relatively small, while the pressure applied on the larger piston is also relatively large, which can keep the liquid stationary. So through the transfer of liquid, different pressures at different ends can be obtained, achieving the goal of transformation. The hydraulic jack commonly used by people utilizes this principle to achieve force transmission. The screw jack pulls the handle back and forth, and pulling the claw pushes the ratchet clearance to rotate. The small umbrella gear drives the large umbrella gear, causing the lifting screw to rotate, thereby enabling the lifting sleeve to lift or lower and achieve the function of lifting tension, but it is not as simple as hydraulic jacks.