1. The oil suction circuit is blocked, the hydraulic oil is insufficient, and the oil circuit is empty. It is easy to make the hydraulic pump unable to absorb oil or insufficient oil suction, resulting in the whole machine not working. It is necessary to check whether the oil suction filter is blocked, the oil tank level and oil quality.
2. Generally, there are more than two main pumps of hydraulic excavator supplying oil to the system. If the main shaft of the pump cannot rotate due to mechanical failure, it is impossible for several pumps to fail. In order to detect the output pressure of the hydraulic pump, an oil pressure gauge can be installed at the pressure tap of the pump to judge whether the pump is faulty.
3. When the safety locking valve is blocked or jammed, the oil cannot push the main control valve to act through PPC valve, causing the whole machine not to act, so it is necessary to clean or replace the safety locking valve in time.
4. When the set pressure of the spring in the main relief valve is too low or the spring breaks, the pressure of the whole system will become too low, and the pressure oil of the main pump can not push the actuator to work, which will cause the whole machine not to move.
5. When diagnosing, start the engine first, connect the safety lock valve, and operate the handle to make the machine dig or rotate. When the safety lock valve fails, it will cause the whole machine not to move. If the main relief valve body is hot and hot by hand, it indicates that the main relief valve is faulty, and it needs to be overhauled and the pressure of the valve is reset.
