The hydraulic pump is a hydraulic element which provides the pressurized liquid for the hydraulic drive, and is a kind of pump. Its function is to convert the mechanical energy of the power machine (such as motor and internal combustion engine, etc.) to the pressure energy of the liquid. The working principle of the single column piston pump is shown in the figure. The cam is driven by the motor. When the cam pushes the plunger upward movement, the sealing volume of the plunger and the cylinder body is reduced, the oil is extruded from the sealed volume and the valve is discharged to the desired place.
When the cam rotates to the descending part of the curve, the spring forces the plunger downward to form a certain vacuum degree, and the oil in the tank enters the sealing volume under the action of the atmospheric pressure. The cam keeps the plunger up and down, the sealing volume decreases and increases periodically, and the pump continues to suck oil and drain oil.