Abnormal operation of boom and swing caused by damage of hydraulic system components

If the fault diagnosis is in the working unit hydraulic system and the boom and swing are not working properly. There are many reasons for this failure. In addition to the boom spool valve leakage and other fault causes, the main safety valve, hydraulic pump, oil filter, hydraulic oil and distribution valve inlet and return oil circuit faults may all cause this fault phenomenon. If the system pressure is low, it may be caused by leakage in the distribution valve. The following will explain how to check the internal leakage of the distribution valve. The inspection methods are different due to different models. This article is for reference only.
After checking and handling the total pressure of the system, if it still works abnormally, check the boom and bucket first. If the above checks are normal, measure the pressure of the corresponding working oil circuit. Measure with pressure gauge. When it is in the two working states of “swing” and “boom lift”, the pressure of its working oil circuit is only 10MPa and the oil pressure of the pilot control system is only 0.5MPa. The working oil pressure and the pilot control system oil pressure in other working conditions meet the normal value. Then carefully analyze according to the working principle diagram of the hydraulic system. It is found that the pilot oil circuit of swing control priority and boom control priority can be connected with the oil circuit of left travel control valve and straight travel valve. Therefore, it is preliminarily judged that there is high pressure oil in the “left travel control valve” acting on the “straight travel shuttle travel valve”. Make the valve core of “linear travel shuttle valve” not in the middle position. The pilot control oil circuit of “swing” and “boom lifting and lowering” passes through the “shuttle valve” and “straight travel valve” and is bypassed for pressure relief. Later, when the “left travel” operating handle is slightly operated, the “swing” and “boom lift” actions will be accelerated. Therefore, it is judged that the “spring and oil seal” at the end of the “left travel control valve” is damaged. After disassembling the “left travel control valve”, it was found that the oil seal and spring were obviously damaged. The fault was solved after replacing the spring and oil seal.