Working principle:

　　Jacks are divided into mechanical jacks and hydraulic jacks, and their principles are different. In principle, the most basic principle on which hydraulic transmission is based is Pascal's law, that is, the pressure in all parts of the liquid is the same. In this way, in a balanced system, the pressure exerted on the smaller piston is relatively small, while the pressure exerted on the larger piston is relatively large, which can keep the liquid still. Therefore, through the transmission of the liquid, You can get different pressures at different ends, so you can achieve the purpose of transformation. The common hydraulic jack uses this principle to achieve force transmission. The screw jack moves the handle back and forth. Pulling the claw pushes the ratchet clearance to rotate, and the small bevel gear drives the big bevel gear to rotate the weight 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.

　　Operation technology:

　　(1) The foundation of jack. The foundation of jack should be smooth, solid and reliable. When setting the jack on the bottom, it should be padded with dowels or other appropriate materials to expand the stress area.

　　(2) Placement of jack. When placing jack on soft ground, you should pad a wooden block under the jack to avoid the danger of tilting after being stressed. When the weight rises, you should always put a supporting pad under the weight, but your hands should not enter the danger zone. During the placement of jack, keep the line of action of load center of gravity consistent with the jack axis. During jacking, you should guard against the danger of jack tilting due to the foundation deflection or horizontal displacement of the jack. To prevent jack.

　　(3) Jacking operation. The jacking height of the jack should not exceed the effective jacking distance. When lifting large objects, the two ends should take off and land separately, one end should take off and land, and the other end must be padded, fastened and stabilized. Jacks are not allowed to be overloaded.

　　Start the jack should not be urgent, it should rise at a constant pace, and descend slowly. When multiple jacks are used at the same time, they should operate synchronously. After the jacks are operated, they should be carefully checked, check the oil pressure and hidden dangers, maintain them, and put them in an appropriate place.