Excavator right travel and bucket no action, boom and stick action slow
According to the owner of the excavator, the failure occurred after replacing the seal of the control valve assembly. After the measurement, the pressure of the bucket is 1.5MPa, which is far less than the normal value of 28.5mpa. When preparing to exchange two-way valves, it is found that the valve position on the fault side is a plug, while the original plug is installed with a valve. After exchanging the correct position, the machine is normal. After the original maintenance personnel replaced the seal of the control valve assembly, the valve and plug position of the group of valves were reversed.
After refitting the excavator to lengthen the arm, the whole vehicle is slow and powerless
The owner said that he had just replaced the oil seal of the pilot pump, but it worked normally for more than ten minutes after the replacement, and then it suddenly failed. Based on this situation, it is first suspected that the pilot pressure is insufficient. After testing, the pilot pressure is low, so it is decided to disassemble the pilot pump. It is found that the skeleton oil seal of the input shaft of the pilot pump has been squeezed out. There are two reasons for this: one is the installation problem; the other is that the pressure is too high. Continue to decompose, found that the oil seal direction of the pilot pump is reversed. This is the cause of the failure. When the framework oil seal was just started to work, it was not completely damaged, but could still work normally. Because the framework oil seal could only bear low pressure, the oil seal was quickly damaged, leading to the pilot pressure oil leaking from the damaged place.
After refitting the excavator to lengthen the boom, the piston rod of the stick cylinder retracts automatically after the engine starts, and other actions are normal
After inspection, one of the other actions is normal; the second one sinks quickly after lifting the boom. After exchanging the dipper stick, the failure is still the same, indicating that the fault is in the control valve or stick cylinder, in line with the principle of easy before difficult. When the control valve rod was disassembled and inspected, it was found that the valve rod was stuck in the retracted position of the piston rod. The valve rod was removed after being vibrated with rubber cocks and copper rods. It can be seen that there are shining iron dust, and the connecting bucket stick sinks quickly. It was determined that the root cause of the failure was the pull of the bucket rod cylinder of the excavator's lengthening arm, which was confirmed after the removal and inspection of the stick cylinder.
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