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 various manufacturers are different, and the standards of large and small arms and bucket cylinder rods are also different. There are many reasons for hydraulic cylinder displacement of excavator, including hydraulic cylinder failure and failure other than hydraulic cylinder. This article will explain the reasons for the static displacement of the hydraulic cylinder except that the hydraulic cylinder enters the air, which is for reference only.
1. Check the assembly accuracy of hydraulic cylinder
When the piston rod and piston are not concentric, correct their coaxiality. Straighten the piston rod when the piston rod is bent. The matching of piston rod and guide sleeve shall be H8 / F8, and the sealing ring qualified by the regular manufacturer shall be used in strict accordance with the size standard and quality standard. When V-shaped sealing ring is adopted, the sealing friction shall be adjusted to a moderate degree.
When the connection point between the load and the piston rod is as close as possible to the sliding surface of the guide rail. The axial line of piston rod shall be consistent with the load center line. The contact length with the guide rail should be as long as possible. The connection position between the load and the hydraulic cylinder shall be subject to the fact that the thrust of the hydraulic cylinder does not tilt the load. Better guidance, better machining accuracy and assembly accuracy, and pay attention to lubrication.
2. Check the seal of hydraulic cylinder end cover
Adjust the sealing ring so that it is not tight or loose. The guide sleeve is concentric to ensure that the piston rod can move back and forth by hand or only tapping with a hammer, and a layer of oil film is hung on the piston rod.
3. Check the assembly and lubrication of guide rail
Measures can be taken to clean and dredge the guide rail lubrication device, readjust the lubrication pressure and lubrication flow, and apply a layer of anti displacement oil between the relative moving surfaces of the guide rail.
