Excavator hydraulic pump fault diagnosis method

The fault diagnosis method of excavator hydraulic pump can be divided into instrument diagnosis method and manual diagnosis method. The instrument diagnosis method is physical test method. The artificial diagnosis method uses vision, touch, smell and hearing to perform preliminary diagnosis on the technical status and faults of hydraulic pumps. The editor of VOLVO construction machinery parts introduces some commonly used instrument detection and diagnosis methods to quickly analyze oil quality. The basic principle of rapid oil analysis is to reflect the aging degree of the oil in use through the change of the comprehensive dielectric constant. The fast oil quality analyzer not only provides a quick and easy oil quality detection method for the hydraulic system of construction machinery, but also can monitor the running status of the equipment and prevent accidents through regular detection of the oil in use. The traditional regular oil change mode in equipment management has been changed, and the scientific oil change according to quality has been realized. The method can quickly detect the physical and chemical properties of the hydraulic oil on site, and judge whether the failure of the hydraulic pump is caused by the deterioration of the hydraulic oil.


       Hydraulic system tester. Since the pressure of the excavator hydraulic pump remains unchanged within the adjustment range, the Volvo excavator parts hydraulic system tester can be used to measure the flow rate of the hydraulic pump to judge its working state. The hydraulic testing machine is generally composed of a pressure gauge, a flow meter, a tachometer, etc. According to the connection method of the testing machine in the pipeline, it can be divided into a straight-through test method and a bypass test method. Install the tester on the high-pressure pipeline of the oil pump by the bypass method, make the oil pump run at the rated speed, and the hydraulic oil temperature is about 60℃. Observe and record the flow reading of the tester when it is not loaded, and then load it with the loading valve to make the load The pressure is gradually raised to the rated pressure of the system, observing and recording the flow reading at this time. If the measured flow is 25% lower than at no load, the hydraulic pump is faulty. If the flow reading decreases by 50%, it can be determined that the hydraulic system failure is caused by the hydraulic pump and the excavator must be disassembled for repair.

        noise meter. The normal noise limit for excavator hydraulic pumps is 105dB. If the limit is exceeded, it may be due to misalignment of the motor and pump drive shaft, or excessive wear of the air entering the interior or the hydraulic pump. thermometer. Diagnose faults by testing the difference between the hydraulic pump casing temperature and the hydraulic oil temperature. If the temperature of the pump casing is higher than the change of the oil temperature by 5°C, it may be that the mechanical efficiency of the hydraulic pump is too low and the mechanical wear is large. If the temperature difference exceeds 10°C and the system pressure setting is normal and the oil quality is normal, it may be due to the large axial clearance, serious wear of the hydraulic pump, reduced volumetric efficiency and increased leakage. pressure gauge. Since the hydraulic pump of the excavator adopts constant pressure control, the pressure of the hydraulic pump system of the excavator cannot reflect the working state of the hydraulic pump, but the fault of the pump can be judged by the swing of the pointer of the pressure gauge. If the deflection of the pressure gauge pointer exceeds ± 200KPa or the swing is very slow, it is an abnormal phenomenon.