一台Ｗ４－６０Ｃ型挖掘机作业时出现动臂只能向左转动而不能向右转动的故障，并且转动速度也较正常时慢。经分析，故障原因可能出在回转液压油路中的安全阀、回转马达或回转操纵阀等处。检查安全阀和操纵阀，未见异常；拆卸回转马达检查其上的零部件，结果也都完好；装复后试 When a W4-60C excavator is working, there is a problem that the boom can only rotate to the left and cannot rotate to the right, and the rotation speed is also slower than normal. After analysis, the cause of the malfunction may be in a safety valve, a rotary motor, or a rotary valve in the rotary hydraulic circuit. Check the safety valve and control valve, no abnormalities are found; disassemble the slewing motor and check the parts on it; the results are all in good condition;