1. If the main safety valve is damaged, the system operation will not be able to reach the normal operating pressure, and the action of the driving device should be abnormal. However, in the early stage of the failure of the machine, only the posture of the stick cylinder is abnormal, and the failure of the main safety valve can be basically checked. .
2. Disassemble the main control valve of the piston rod cylinder, and find that the valve core is offset and negatively correlated, so that the main oil passage is always in the open position; when taking the valve core, it is found that the adsorption force in the opposite direction is relatively large, and the valve core is difficult to move; the oil passage is relieved , After removing the valve core, the valve core moves freely without jamming.
3. Check the secondary main working pressure output by the main control oil passage, the system pressure is also normal, and the common faults of the main pressure regulating valve can be checked. If the speed regulating valve at the main control valve port of the piston cylinder is damaged, the oil passage leading to the piston cylinder will not be able to build up pressure, and the piston cylinder will not be able to operate.
4. Check the remaining oil of the hydraulic oil filter element, the remaining oil is sufficient, but after removing the inlet and return hydraulic oil filter elements, it is found that some iron pins are attached to the main valve inlet hydraulic oil filter element; check the pressure of the main valve system, the main valve Stress, dominant work pressure are normal. The noise caused by the analysis of the main valve working may be caused by the suction of the iron pin by the hydraulic oil filter element.
