There are two types of jacks, mechanical jacks and hydraulic jacks, with different principles. In principle, the principle based on the hydraulic jack is the Pascal principle, that is: the pressure across the liquid is the same, so that in a balanced system, the pressure exerted on the smaller piston is smaller, and the larger piston The pressure applied is also relatively large, which can keep the liquid still. Therefore, through the transfer of liquid, different pressures on different ends can be obtained, so that a transformation can be achieved. The hydraulic jack that we commonly see uses this principle to achieve force transmission. The mechanical jack adopts the mechanical principle. The handle is pulled back and forth, and the pawl is pulled to push the ratchet gap to rotate. The small bevel gear drives the large bevel gear to rotate the lifting screw, so that the lifting sleeve can be raised or lowered to achieve the lifting force. Features. But it is not as simple as a hydraulic jack.