If the hydraulic oil filter has not been replaced for an extended period, it may cause the bypass valve on the filter to open, allowing impurities in the unfiltered hydraulic oil to directly enter the sliding surface of the center swivel joint, which in turn leads to damage to the seal ring. As a result, when the excavator is moving, one side of the pressure oil will leak, causing an imbalance in the speed of the two travel motors, ultimately leading to the excavator veering off course.

Solution: It is necessary to replace the oil seal on the center swivel joint in a timely manner, and simultaneously replace the hydraulic oil and filter element to ensure the excavator moves normally