After the excavator shuts down the engine, the hydraulic cylinder rod will produce a certain displacement under this static state. This phenomenon is common but helpless for excavator drivers. When each excavator leaves the factory, there is a certain quantitative standard for the displacement index of the hydraulic cylinder. It is best to have no displacement in the ideal state. It is difficult to achieve in the actual manufacturing process, so there are standard upper and lower limits. When the displacement exceeds the upper and lower limits, it can be determined that the excavator is faulty. The limit standards of each manufacturer are different. There are many reasons for hydraulic cylinder displacement of excavator, including hydraulic cylinder failure and failure other than hydraulic cylinder. The most common reason is that the hydraulic cylinder enters the air. What should be done when the excavator hydraulic cylinder enters the air and causes displacement in the static state? This article will describe the solution to this problem for reference only.
1) If the oil is mixed with air and the air is sucked from the hydraulic pump, the air inlet fault of the hydraulic pump can be eliminated first.
2) For new hydraulic cylinders, repaired hydraulic cylinders or hydraulic cylinders with long equipment shutdown time, there will be air in the cylinder and pipeline. It can be vented through the bleeder plug of the hydraulic cylinder. For the hydraulic cylinder without special exhaust device, slightly loosen the inlet and outlet pipe joints at both ends of the hydraulic cylinder and run back and forth for several times to exhaust the hydraulic cylinder. If the oil leaked from the joint changes from white to clear, it indicates that the air has been removed. At this time, the pipe joint can be tightened again. For hydraulic cylinders that are also difficult to exhaust air by this method, the methods of loading exhaust and filling oil into the cylinder can be used to exhaust the air.
3) For the situation that negative pressure will be formed in the cylinder and it is easy to inhale air from the piston rod, pay attention to the rationality of the sealing design of the piston rod.
4) After startup, let the hydraulic cylinder run at the maximum stroke and speed to force the gas to be discharged.
