Constant pressure variable pump, in its variable range to keep the system pressure constant not affected by the pump flow rate changes, variable pump only provide the necessary flow rate. Constant pressure variable pump, in its variable range to keep the system pressure constant not affected by the pump flow changes, variable pump only provide the necessary flow rate. When the system pressure is lower than the set limit pressure, the pump maintains maximum flow. When the system pressure is lower than the set limit pressure, the pump maintains maximum flow. When the system pressure increases close to the set limit, the pump flow rate automatically decreases, providing only the minimum flow rate that maintains a constant system pressure. When the system pressure increases close to the set limit, the pump flow rate automatically decreases, providing only the minimum flow that maintains a constant system pressure. During the flow drop, the pressure of the pump remains constant. During the flow drop, the pressure of the pump remains constant. The pressure limiting pressure can be manually adjusted by the control valve; The pressure limiting pressure can be manually adjusted by the control valve; Suitable for hydraulic system working at constant pressure point for a long time, reducing power consumption and saving energy; Suitable for hydraulic system working at constant pressure point for a long time, reducing power consumption and saving energy; It can be directly connected to the special motor of the oil pump, which is easy to assemble and has a beautiful appearance. Can be directly connected with the special motor of the oil pump, easy to assemble, beautiful appearance.