挖掘机行走和铲斗无动作，动臂和斗杆动作慢

Excavator walking and bucket not moving, boom and stick moving slowly

很多人反映在更换完控制阀总成的密封后即出现此故障。测后泵收铲斗时的压力为1.5Mpa，远小于正常值的28.5Mpa。在准备交换两路的安.全阀时，发现故障一侧的位置上为一堵头而原堵头的位置却安装了安.全阀。交换正确位置后机器正常。原来维修人员更换完控制阀总成的密封后，将该组阀的阀门与堵头位置装反。

Many people have reported that this fault occurred after replacing the seal of the control valve assembly. The pressure when the pump collects the bucket after measurement is 1.5Mpa, which is much lower than the normal value of 28.5Mpa. When preparing to exchange two safety valves, it was found that there was a plug on the faulty side, but the original plug was installed with a safety valve. After swapping the correct position, the machine is functioning normally. After the maintenance personnel replaced the seal of the control valve assembly, they installed the valve and plug position of the group of valves in the opposite direction.

改装成挖掘机加长臂后，全车慢、无力

After being modified into an excavator with extended arms, the entire vehicle is slow and powerless

有人反映刚更换了先导泵油封，但更换后工作了十几分钟一直很正常，然后突然就不行了。根据此情况，怀疑先导压力不足。经测试挖掘机加长臂的先导压力非常低，决定分解先导泵。

Someone reported that the pilot pump oil seal had just been replaced, but it worked normally for more than ten minutes after the replacement, and then suddenly stopped working. Based on this situation, it is first suspected that the pilot pressure is insufficient. After testing, the pilot pressure of the excavator's extended arm was very low, and it was decided to disassemble the pilot pump.

发现先导泵输入轴的骨架油封已挤出，此原因有两种：一是安装问题，二是该处压力过高。继续分解发现先导泵的油封方向装反。此处才是故障的原因，当刚开始工作时，骨架油封没有完全损坏，仍可正常工作，因骨架油封只能承受低压，故油封很快损坏，导致先导压力油从损坏处泄出。

It was found that the skeleton oil seal of the input shaft of the pilot pump has been squeezed out. There are two reasons for this: installation problems and high pressure at that location. Further disassembly revealed that the oil seal of the pilot pump was installed in the opposite direction. This is the cause of the malfunction. At the beginning of work, the skeleton oil seal was not completely damaged and can still function normally. As the skeleton oil seal can only withstand low pressure, it quickly damaged, causing pilot pressure oil to leak out from the damaged area.

发动机起动后斗杆油缸的活塞杆自动缩回

The piston rod of the stick cylinder automatically retracts after the engine starts

经检查，一其余动作正常;二提起动臂后斗杆下沉较快。交换斗杆先导管后故障依旧，说明故障在控制阀或斗杆油缸，本着先易后难的原则。拆检控制阀杆，发现阀杆卡在活塞杆缩回位置，用橡胶螂头和铜棒震动后取出阀杆。可见有闪亮铁末，联系斗杆下沉较快。判断故障根源为挖掘机加长臂斗杆缸筒拉伤，拆检斗杆油缸后证实。

After inspection, all other actions were normal; After lifting the boom, the stick sinks quickly. If the malfunction still persists after exchanging the handle, it indicates that the malfunction is in the control valve or handle oil cylinder, following the principle of easy first and difficult later. After disassembling and inspecting the control valve stem, it was found that the valve stem was stuck in the retracted position of the piston rod. After vibration with a rubber cock and a copper rod, the valve stem was removed. There is visible shiny iron powder, indicating that the bucket handle sinks quickly. The root cause of the malfunction was determined to be a pulled cylinder on the extended arm of the excavator, and it was confirmed after disassembling and inspecting the cylinder.

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