1.斗杆自动下落(1)故障现象1台小松PC220型挖掘机在作业过程中出现斗杆自动下落故障。(2)故障排查首先,检查斗杆缸“漂移”量。得知斗杆缸自动伸出量为600mm/min,比极限值240mm/min多出360mm/min。其次,进行斗杆缸漏油测试。经检测得知斗杆缸漏油量≤20mL/min,在正常范围之内,这说明斗杆缸无故障,故障应发生在控制阀上。最后,检查控制阀。经检查斗杆阀和安全吸油阀正常,但是检查斗杆压力补偿阀时,发现其密封圈损坏。更换该 1. Stick automatically fall (1) Fault phenomenon 1 Komatsu PC220 excavator in the course of the arm automatic fall occurs. (2) Troubleshooting First, check the stick cylinder “drift ” amount. It is known that the arm cylinder automatically protrudes by 600 mm / min, which is 360 mm / min more than the limit of 240 mm / min. Second, the arm cylinder oil spill test. After testing that stick cylinder oil leakage ≤ 20mL / min, within the normal range, indicating that arm cylinder without failure, failure should occur in the control valve. Finally, check the control valve. After checking the stick valve and safety suction valve normal, but check the stick pressure compensation valve and found the seal damage. Change this