When the boom is lifted, the boom or jib will fall automatically without the control of the operating lever, which is called arm drop. It is a manifestation of boom weakness. When the excavator fails to drop its arm, it will also appear in different forms. The failure phenomenon can be roughly divided into boom drop, jib drop, middle boom drop, cold vehicle normal hot vehicle drop, etc.
1. Common causes of arm failure
1) Arm drop caused by hydraulic oil failure. When the cold car is normal and the hot car falls off, it is likely that there is a problem with the hydraulic oil.
2) The failure of the hydraulic cylinder of the excavator, especially the damage or aging of the oil cylinder oil seal, resulting in the internal leakage of the oil seal.
3) The distribution valve hole is blocked, the valve core is worn, the valve core clearance is too large, and the main safety valve of the distribution valve is worn and damaged.
4) When the oil seal of large and small arm safety overflow valve is damaged, it will cause certain leakage and arm falling.
5) It is caused by poor sealing of the distribution pump. At this time, the sealing ring of the distribution pump needs to be replaced.
6) Poor contact of the connector of the proportional solenoid valve of the hydraulic pump will also cause the large and small arms to fall off.
7) Serious arm drop, i.e. the oil temperature is about 45 ℃, and the bucket teeth drop more than 95mm in 5 minutes. It is most likely that the main valve is stuck.
2. What should I do when the excavator arm falls off
1) Check the operating ambient temperature of the excavator, whether there is improper selection of hydraulic oil model, and whether inferior hydraulic oil is used.
2) In case of boom drop fault, first reduce the boom pressure and carefully observe whether the boom falls quickly.
3) Check whether the hydraulic oil cylinder and oil cylinder oil seal are faulty. If the oil seal is poor, it will leak oil. Replace the oil seal in time.
4) After replacing the oil seal, if the boom is returned, check the distribution valve and boom return safety valve.
5) Check whether the working pressure and pilot pressure of the excavator main hydraulic pump meet the requirements.
