How to judge the failure of hydraulic pump of excavator

The methods for judging the failure of an excavator’s hydraulic pump can be divided into two categories: instrument diagnosis and manual diagnosis. A physical test is used to diagnose an instrument. The hydraulic pump’s technical state and problems are initially diagnosed using the manual diagnosis method, which employs vision, touch, smell, and hearing. The following are some of the most common instrument test diagnostic methods:

1、Quick oil quality analysis

The primary premise of quick oil quality analysis is to use the change in the comprehensive dielectric constant to reflect the aging degree of the oil in use. The rapid oil quality tester not only provides a quick and simple technique for detecting oil quality in the hydraulic system of construction gear, but it also monitors the equipment’s working status by inspecting the oil in use on a regular basis to prevent mishaps. The old practice of frequent oil changes in equipment management has been replaced by scientific oil changes based on quality. This approach may identify numerous physical and chemical performance indicators of hydraulic oil on the spot, allowing you to determine whether the failure of the hydraulic pump is due to hydraulic oil deterioration.

2、Hydraulic system tester

The hydraulic system tester can measure the flow of the hydraulic pump to judge its working condition because the pressure of the excavator’s hydraulic pump remains constant within the adjustment range. A pressure gauge, a flow meter, and a tachometer are common components of a hydraulic tester. A straight-through test technique and a bypass test method can be distinguished based on the connection method of the tester in the pipeline. Install the tester using the bypass technique on the oil pump’s high-pressure pipeline, run the oil pump at the rated speed, and ensure that the hydraulic oil temperature is around 60°C. The load pressure progressively increases to the system’s rated pressure. At this time, keep an eye on the flow readings and make a note of them. If the observed flow rate drops by 25% when compared to no-load, the hydraulic pump has failed; if the flow reading lowers by 50%, the hydraulic system failure is due to the hydraulic pump, which must be disassembled and repaired.

3、Noise meter

The hydraulic pump of an excavator has a noise restriction of 105 decibels. If this limit value is exceeded, it could be due to a misalignment of the motor and pump drive shaft, air entering the inside, or a damaged hydraulic pump.


The temperature differential between the excavator’s hydraulic pump casing and the temperature of the hydraulic oil can be used to diagnose the problem. If the pump casing temperature is 5°C or more higher than the oil temperature, the hydraulic pump’s mechanical efficiency is too low, and mechanical wear is excessive; if the temperature difference is greater than 10°C, and there is no problem with the system pressure setting or oil quality, it could be the shaft. Large directional clearance, severe hydraulic pump wear, decreased volumetric efficiency, and increased leakage are all issues that need to be addressed.

5、Pressure gauge

Because the excavator’s hydraulic pump uses continuous pressure control, the pressure of the hydraulic pump system cannot show the hydraulic pump’s operating condition, but the swing of the pressure gauge pointer can indicate oil pump failure. It is an abnormal occurrence if the pressure gauge pointer deflection exceeds 200kpa or the swing is very slow.

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