1. The digger moves right and the bucket does not move, the moving arm and the bucket pole move slowly.
According to the response of the owner of the excavator, after replacing the seal of the control valve assembly, the defect appears. After measurement, the pressure of the pump bucket is 1.5 Mpa, which is much lower than the normal value of 28.5 Mpa.
When preparing to exchange two-way valves, it is found that there is a plug on the valve azimuth of the defective side, while the original plug azimuth is equipped with a valve. The machine is normal after the correct azimuth is exchanged. After replacing the seal of the control valve assembly, the original maintenance personnel installed the valve and the plug position of the group of valves in reverse.
2. After refitting the excavator to lengthen the arm, the whole vehicle is slow and weak.
The pilot pump oil seal has just been replaced by the host, but it has been working normally for ten minutes after replacement, and then suddenly no longer works. According to this situation, the first suspect is the lack of pilot pressure.
After testing, the pilot pressure is very low and the pilot pump is decided to differentiate.
It is found that the skeleton oil seal of the input shaft of the pilot pump has been extruded. There are two reasons for this: one is the device problem, the other is that the pressure is too high. Continuous differentiation found that the oil seal direction of the pilot pump was reversed.
This is the reason for the trouble. When the skeleton oil seal is not completely damaged at the beginning of operation, it can still work normally. Because the skeleton oil seal can only withstand low pressure, the oil seal is damaged quickly, leading to the leakage of pressure oil from the damaged place.
3. After refitting the excavator to lengthen the arm, the piston rod of the bucket rod cylinder retracts actively after the engine starts, and other actions are normal.
After checking, one of the other movements is normal, and the bucket rod sinks faster after the second lifting of the starting arm. The defect of the exchange bucket rod is still the same after the conduit. It is stated that the defect is in the control valve or the bucket rod cylinder, based on the principle of easy first and difficult later.
The control valve stem was disassembled and checked. It was found that the valve stem was stuck in the retracted position of the piston rod. The valve stem was removed after being stirred by a rubber Hydra head and a copper rod. It can be seen that there are shining iron poles, the connection bucket rod sinks faster. The origin of the defect was found to be the pull of the cylinder of the extended arm bucket rod, which was confirmed after the bucket rod cylinder was dismantled and inspected.
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