汽车起重机在进行起重作业时，支腿液压缸因长时间承受较大负载，易使活塞Ｙ形密封因失效，造成支腿油缸内泄，导致起重机站立不稳，甚至发生翻车事故，这就是我们常说的“软腿”现象。对于此类故障，通常的解决方法是更换密封圈；但在实际工作中，事故多发生在野外工地，因缺 Truck cranes in the lifting operation, the leg hydraulic cylinder due to a long time to bear a greater load, easy to make the piston Y-seal failure, resulting in leg cylinder leakage, leading to unstable crane, or even rollover accidents, which is We often say the “soft leg” phenomenon. For such failures, the usual solution is to replace the seal; but in actual work, the accident occurred in the field site, due to lack of