When using the plunger pump, when the piston in the role of external force to move to the right, the pump body is likely to cause negative pressure, the upper one-way valve (discharge valve) is pressed and closed, the lower one-way valve (Suction valve) is pushed away by the pressure of the liquid outside the pump, drawing the liquid into the pump body. In contrast, when the piston moves leftward, a high pressure is generated in the pump body, the suction valve is pressed and closed, and the discharge valve is pressurized and opened, thereby discharging the liquid from the pump. Piston pump how to change the pressure So, the piston constantly reciprocating motion, the liquid intermittent and continuous inhalation and discharge. Its characteristics: rely on the piston to work on the liquid, the energy in the form of static pressure directly to the liquid. How to change the pressure of the plunger pump to adjust the working status when it is used in production. The type of variable displacement axial piston pump with adjusting screw above the pump is automatically controlled by the pressure of the pump itself, as shown in Figure 3 High pressure oil flow passage (a), (b), (c), into the variable housing (302) (F) and (h), respectively, through the passage (e) when the force of the spring is greater than the hydraulic thrust force entering the lower end annular area of ​​the servo piston (309) from the passage (f) (H) into the upper chamber (g), pushing the variable piston (301) to move downward, increasing the flow of the pump. Conversely, when the pump pressure overcomes the spring force to move the servo piston upwards, the passage (h) is blocked, causing (g) the chamber oil to depressurize through (i) and the variable displacement piston moves up and the pump flow decreases. Piston pump has the advantages of high volumetric efficiency, stable operation, good flow uniformity, low noise and high working pressure, but it is sensitive to the pollution of hydraulic oil, the structure is complex and the cost is high. Such products play an increasingly important role in the current production, and related research institutes and businesses should devote more energy to product development and research.