Constant pressure pump is generally used in such hydraulic systems: the beginning of the requirements of low-voltage fast-forward, and then slowly turned around, and finally stops moving and packing, as the hydraulic machine is. Here variable displacement pump, constant pressure pump system is set dwell pressure required. Here, "the decision by the load pressure of the hydraulic system, and the relief is applied to define the" basic principles should say is met. To better understand the pump control system, can be considered to "determine the hydraulic system pressure variable pump oil spill by the load, but by the constant pressure applied to limit the pump." Like the example of the press reaction force moldings can be large, depending how much adjustment is applied by the constant pressure pump. Pressure variable piston pump is made variable cylinder and pressure regulator components. Constant pressure pump does not reach the set pressure regulating valve on the pump before construction machinery variable pump, variable pump swash plate at the maximum angle, the pump displacement and maximum displacement constant, constant pressure at this stage is actually quite variable pump dosing pumps. After reaching the set pressure regulating valve, control of oil into the cylinder variable variable vane pump, variable cylinder push pump displacement swash plate decreases. In the constant variable pump system, if there is relief valve, pressure regulator valve on the pump is set to be less than the system relief valve set pressure 0.5-1Mpa. Otherwise pump pressure regulating valve can not reach the set value, it can not pump variable domestic variables, creating hydraulic crystal quality assurance (certified), variable pump from Jinan Jing Chong hydraulic machinery Limited. Jinan Jing Chong Hydraulic Machinery Co., Ltd. (www.jnjcyy.com) (www.jnjcyy.com) Shandong Jinan, mining machinery leaders, over the years, the company is implementing the scientific management, innovation and development, the principle of honesty and trustworthiness, the maximum meet customer needs. In the crystal to create a hydraulic leadership with the staff warmly welcome all inquiries negotiations to create the crystal to create a better future for the hydraulic.