After the excavator hydraulic pump is severely worn, we search for the causes of common faults according to the following three points, and the system improves them:

(1) Check the air leakage condition of the boom cylinder. A very simple way is to slowly raise the boom to see if it is significantly lowered at will. If the drop is significant, disassemble the oil cylinder for inspection, and replace the seal ring if it is worn.

(2) Check the control valve. Clean the valve first, check whether the valve core is worn, and replace it if worn. If there is no change after the valve is installed, check the wear condition of the control valve core again. The application degree of the clearance is generally 0.06mm, and it should be replaced if the wear is serious.

    (3) Hydraulic motor of planetary reducer The brakes measure the pressure of the excavator hydraulic pump. If the pressure is slightly low, adjust it. If the pressure cannot be adjusted, it indicates that the hydraulic pump is severely worn.

In general, the key reasons why the boom load cannot be increased are:

a. The hydraulic pump of excavator is severely worn. The leakage in the pump is serious when operating at low speed; During high-speed operation, the pump pressure is slightly increased, but because of the wear and internal leakage of the pump, the capacity and efficiency are significantly reduced, and it is difficult to achieve the rated pressure. In the long-term operation of the hydraulic pump, the wear was aggravated, and the oil temperature was high, which led to the wear of the hydraulic system, the embrittlement and destruction of the hydraulic seals, the lack of sealing capacity, and the mildew of the gear oil, which eventually led to common failures.

b. The selection of hydraulic system model is not scientific. The specification and model of boom oil cylinder is 70/40 non-standard series products, and the hydraulic seal is also non-standard, so the manufacturing cost is high and the removal and replacement of hydraulic seal is troublesome. The small diameter of the boom cylinder will inevitably make the system software control precision pressure high.

    c. Hydraulic transmission The system design scheme is unscientific. Connecting rod free radial Hydraulic motor of cone crusher It is connected with the hydraulic steering system by a single pump in series. The valve control precision pressure is 16MPa, and the rated working pressure of the excavator hydraulic pump is 16MPa. The hydraulic pump often works under full load or long-term overload (high pressure), and the system software has hydraulic transmission impact, and does not change the oil for a long time. The gear oil is polluted by the environment, which aggravates the wear of the hydraulic pump, and even causes the hydraulic pump body to burst (this kind of common fault was found later).