What are The Performance Parameters of The Hydraulic Pump

Hydraulic pump is the power element of the hydraulic system, its function is to provide pressure oil to the hydraulic system, from the energy conversion point of view, it will be the mechanical energy output of the prime mover (such as the engine) into the pressure of the liquid to facilitate delivery. The hydraulic motor is an executive component, which can convert the pressure of the input liquid into the mechanical energy of the output shaft rotation, used to drag the load to do work. According to the structure form, hydraulic pump and hydraulic motor can be specifically divided into gear type, vane type, plunger type and other types.

Hydraulic Pump Pressure

Hydraulic pump operating pressure is the pump (or motor) in the actual work of the output (or input) fluid pressure, determined by the external load.

Rated pressure is the highest pressure that can operate continuously under normal working conditions, according to the test standard. Its size is limited by the life, if more than rated pressure work, the pump (or motor) life will be shorter than the designed life. When the working pressure is greater than the rated pressure is called overload.

Rotational Speed

Operating speed refers to the actual speed of rotation of the pump (or motor) during operation.

The rated speed is the highest speed that can operate normally for a long time under the rated pressure. If the pump more than the rated speed will cause insufficient oil suction, vibration and large noise, parts will suffer cavitation damage, reduce life.

The minimum stable speed is the minimum speed allowed for the normal operation of the motor. In this speed, the motor does not appear crawling phenomenon.

Displacement and Flow Rate

Displacement is the volume of liquid discharged (or input) by the change in geometry of the sealed cavity for each revolution of the pump (or motor), commonly used unit is ml/r (ml/rev). Displacement can be adjusted to change the variable pump (or variable motor), the displacement can not change the quantitative pump (or quantitative motor).

The actual flow rate is the flow rate at the outlet (or at the inlet) when the pump (or motor) is operating. Because of the internal leakage of the pump itself, its actual flow is less than the theoretical flow. As the motor itself also has internal leakage, to achieve the specified speed, in order to compensate for the leakage, its input actual flow rate must be greater than the theoretical flow rate.

Efficiency

The volumetric efficiency of a hydraulic pump is the ratio of its actual flow rate to its theoretical flow rate. For hydraulic motor is the ratio of its theoretical flow rate to the actual flow rate.

Mechanical efficiency, for the hydraulic pump is the ratio of its theoretical torque to the actual input torque. For the hydraulic motor, the actual output torque is the torque after the theoretical torque overcomes the friction, so its 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. Total efficiency is equal to the product of volumetric efficiency and mechanical efficiency.

Repair and Maintenance

Cause of failure: oil pump end face or the main and driven gear sleeve end face wear or scratch, two sleeve end face unevenness super poor.

Elimination method: replace the worn gear oil pump or oil pump sleeve, the end face will be ground flat on the flat plate when the wear is slight. Its unevenness allowable error 0.03mm; upper sleeve end face is lower than the pump body, the upper plane (normal value is lower than 2.5 ~ 2.6mm), such as over the difference should be under the sleeve plus 0.1 ~ 0.2mm copper piece to compensate, the installation should be set after the sleeve is installed

Cause of failure: internal leakage caused by incorrect assembly of internal parts of the fuel pump.

Elimination method: unloading piece and sealing ring must be installed into the oil cavity, the two bushings to maintain balance. Guiding steel wire elasticity should be able to simultaneously twist the upper and lower sleeve towards the direction of rotation of the driven gear a small angle, so that the main and driven gear two sleeve processing plane close fit; sleeve on the unload slot must be installed on the low pressure cavity side, in order to eliminate the gear meshing harmful closed volume; press into the self-tightening oil seal before the surface should be coated with a layer of lubricant, but also pay attention to the edge of the oil barrier towards the front cover, can not be installed in reverse; installed pump cover before, must be to the Before installing the pump cover, pour a small amount of hydraulic oil into the pump casing and turn the meshing gear by hand.