目前，绝大部分工程机械采用的溢流阀为先导式溢流阀。当机器运行到中期后，液压元件受工作频率和负荷条件的影响，易损件（包括溢流阀）会相继失效。溢流阀失效有多种原因，因内部泄漏引起系统压力升不高是原因之一，而造成系统压力升不高的原因又是多方面的，如液压泵、操纵 At present, most of the construction machinery used for the relief valve pilot relief valve. When the machine runs to mid-term, the hydraulic components are affected by the operating frequency and load conditions, the wearing parts (including the relief valve) will fail. Pressure relief valve failure for a variety of reasons, due to internal leakage caused by system pressure rise is not high is one of the reasons, and cause system pressure rise is not high because there are many reasons, such as hydraulic pumps, control