The size of the hydraulic system operating pressure are determined by the load, so the size of the working pressure must meet the requirements of a load; in order to ensure the normal operation of the system, system configuration of the relief valve set pressure must be greater than the actual working pressure 15-20%, to ensure the system pressure in up to the working pressure, relief valve without unloading; that is special noted, relief valve setting pressure should not be greater than the rated working pressure of the oil pump, otherwise it will affect the pump service life or failure.
We generally use the product of rated speed of motor and gear pump rated capacity to calculate the flow, product of the working pressure of the system and the system flow we call for hydraulic power; the size of the motor power is determined according to the hydraulic power, the general hydraulic power is about 50-70% of the rate of motor power.