1. Hydraulic pump pressure
Hydraulic pump working pressure refers to the pressure of the pump (or motor) outputting (or inputting) the oil during actual operation and is determined by the external load.
The rated pressure refers to the maximum pressure that can be continuously operated according to the test standard under normal working conditions. Its size is limited by the life. If it exceeds the rated pressure, the service life of the pump (or motor) will be shorter than the designed life. When the working pressure is greater than the rated pressure, it is overloaded.
Working speed refers to the actual rotation speed of the pump (or motor) during operation.
Rated speed refers to the maximum speed that can be continuously operated for a long time under the rated pressure. If the pump is operated beyond the rated speed, it will result in insufficient oil absorption, vibration and loud noise, parts will suffer cavitation damage, and the life will be reduced.
The lowest stable speed is the lowest speed allowed for the normal operation of the motor. At this speed, the motor does not appear to crawl.
3. Displacement, flow
Displacement is the volume of discharge (or input) liquid that results from a change in the geometry of the sealed chamber per revolution of the pump (or motor). The common unit is ml/r (ml/rev). The displacement can be changed to a variable displacement pump (or variable motor), and the displacement cannot be changed to a fixed displacement pump (or fixed displacement motor).
Actual flow refers to the flow at the outlet (or inlet) of the pump (or motor) during operation. Due to the internal leakage of the pump itself, the actual flow is less than the theoretical flow. Because the motor itself also has internal leakage, to achieve the specified speed, in order to compensate for the leakage, the actual input flow must be greater than the theoretical flow.
Volumetric efficiency refers to the ratio of the actual flow rate to the theoretical flow rate for a hydraulic pump. The hydraulic motor refers to the ratio of the theoretical flow to the actual flow.
The mechanical efficiency of a hydraulic pump is the ratio of its theoretical torque to the actual input torque. The actual output torque of the hydraulic motor is the torque after the theoretical torque overcomes the friction force, so the mechanical efficiency is the ratio of the actual output torque to the theoretical torque.
Total efficiency is the ratio of the output power of the pump (or motor) to the input power. The total efficiency is equal to the product of volumetric efficiency and mechanical efficiency.