Working principle of hydraulic jack

The working principle of hydraulic jack is shown in Figure 1

Figure 1 Working principle of hydraulic jack

1. Pump suction process
When the lever handle 1 is lifted by hand, the small piston is driven upward, and the sealed working volume in the pump body 2 increases. At this time, since the oil discharge check valve 3 and the oil discharge valve 8 respectively close their respective oil paths, the working volume in the pump body 2 increases to form a partial vacuum. Under the action of atmospheric pressure, the oil in the oil tank flows into the pump body 2 through the oil pipe to open the oil suction check valve 4 to complete an oil suction operation.


2. Pump pressure oil and heavy lifting process
When the lever handle 1 is depressed, the small piston is driven to move down, the working volume of the small oil chamber in the pump body 2 is reduced, and the oil is squeezed out, and the oil discharge check valve 3 is pushed away (at this time, the oil suction one way Valve 4 automatically closes the oil path to the tank), and the oil enters the hydraulic cylinder (oil chamber) 11 through the oil pipe. Since the hydraulic cylinder (oil chamber) 11 is also a sealed working volume, the incoming oil is squeezed due to The force generated by the pressure will push the big piston up and lift the heavy object to work. By repeatedly lifting and pressing the lever handle, the weight can be continuously raised to achieve the purpose of lifting.

3. The process of falling heavy objects
When the large piston is required to return downward, open the oil drain valve 8 (rotate 90°). Under the action of the weight of the heavy object, the oil in the hydraulic cylinder (oil chamber) 11 flows back to the oil tank 5, and the large piston drops to In situ.

Through the working process of hydraulic jacks, we can conclude that the working principle of hydraulic transmission is to use oil as the working medium, to transmit motion through the change of the sealed volume, and to transmit power through the internal pressure of the oil. The hydraulic transmission device is essentially an energy conversion device.