Why can the excavator boom only turn left?

A W4-60C excavator encountered a malfunction during operation where the boom could only rotate to the left but not to the right, and the rotation speed was also slower than normal.

After analysis, the cause of the fault may lie in the safety valve, rotary motor or rotary control valve in the rotary hydraulic circuit, etc. The safety valve and control valve were inspected and no abnormalities were found. Disassemble the rotary motor to inspect the components on it, and the results showed that they were all in good condition. When the machine was tested after reinstallation, the fault symptoms persisted. However, when pushing the control lever to turn the arm to the right, it was found that the high-pressure rubber hose between the safety valve and the rotary motor was in a "bouncing" state, as if the oil was stuck. When the high-pressure rubber hose was removed for inspection, it was found that the inside had peeled off and was fish-scale-like. When high-pressure oil entered the pipe, the fish-scale-like skin would block the pipeline (the situation was slightly better when the oil returned). After replacing this oil pipe, the boom can immediately turn to the right.

From this, it can be known that after long-term use, the inside of the rubber hose is prone to aging and peeling, which will cause poor oil flow and poor system operation. Users should pay attention to this.