Excavator Hydraulic Pump Failure and Causes

Excavator Hydraulic Pump Failure and Causes

Hydraulic pump is the power source of all hydraulic systems. It is the energy conversion device that converts mechanical energy into hydraulic energy. Its technical performance is directly related to the power and reliability of the vehicle. Hydraulic pump is a high failure rate component of hydraulic system, so what is the main reason for the failure of hydraulic pump?

1. Pump internal parts wear: internal parts wear will cause internal leakage. The leakage area between the floating shaft sleeve and the gear end face is large, which is the main part of the internal leakage. The clearance of the mating surface increases, the volume efficiency decreases due to wear and internal leakage, and the output power of the oil pump is much lower than the input power.
2. Aging of the pump seal element: The aging of the seal element leads to air being sucked into the oil pump from the gap between the oil seal and the spindle journal or from the junction of the oil inlet connector and the oil pump housing, and entering the oil tank through the return tubing, producing a large number of bubbles in the oil tank. The oil in the tank will be reduced, and the lifting will be slow or non-lifting. The oil seal must be replaced to remove the problem.
3. Pump leakage: leakage is directly related to the output flow of the hydraulic pump, will affect the stability of the hydraulic system speed and output power. Reason: the center spring of the plunger pump is damaged, so that the cylinder block and the distribution of oil cross lose the sealing; Oil seal or seal ring damage; Poor sealing surface; Pump parts wear, clearance is too large.
4. Pump oil supply is insufficient or no oil pressure.
5. Excessive noise during pump operation
6. Failure cause: serious vacuity phenomenon; The suction pipe extends into the oil surface is shallow or the oil level of the tank is too low; Hydraulic pump shaft and motor shaft coaxiality difference; Coupling installation is poor, coaxiality and beat; The oil suction filter is partially blocked; Oil viscosity is too high; Suction pipe or pump suction cavity is not smooth; Oil suction end joint seal is not strict, there is air into, oil suction position is too high; Air enters from the oil seal of the pump shaft; Pump cover screw loose; Pump and connecting shaft different heart or loose; There are bubbles in the oil; The passing capacity of suction filter is too small; The rotational speed is too high; Pump body cavity obstruction; Gear pump tooth shape precision is not high or poor contact, pump parts damaged; The axial clearance of the gear pump is too small, the perpendicality of the inner hole and the end face of the gear or the parallelism of the two holes on the pump cover is blocked; Pipeline vibration.
7. Pump no pressure, pump shaft reversal; The pump does not absorb oil.
8. The hydraulic pump works abnormally hot

Cause of failure: poor assembly of pump; The quality of hydraulic oil is poor, and the internal wear is intensified. The return pipe is not smooth; The influence of environmental conditions; Oil viscosity is too high or too low; Serious friction between side plate and shaft sleeve and gear end face; Tank volume is too small, poor heat dissipation

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