１故障现象某厂自制升降台的液压系统如图１所示，采用双泵双回路可实现双缸同时动作或单缸动作。两个回路使用的液压元件规格相同，管路通径相同。在使用中发现，若液压泵１和２同时启动，溢流阀３和４压力不稳定，并出现振动和噪声。试验表明，若其中一个泵启动实现单缸动作 1 Fault phenomenon A self-made lifting system hydraulic plant shown in Figure 1, the use of dual-pump dual-loop can be achieved at the same time double cylinder action or single cylinder action. The hydraulic components used by both circuits have the same specifications and the same pipe diameter. In use, it was found that if the hydraulic pumps 1 and 2 were started at the same time, the relief valves 3 and 4 were unstable in pressure and vibrated and noisy. Experiments show that if one of the pump start to achieve single cylinder action