If it is confirmed through troubleshooting that the bucket overturning is normal due to the hydraulic system fault and only the boom lifting is slow and weak. This shows that the working pump and the main safety valve are working normally. It also shows that the oil quantity and quality of the pipeline and oil filter at the oil inlet end of the pump as well as the oil tank are all right. At this time, it is only necessary to check the boom spool valve, boom oil cylinder, boom oil pipe and its seals. It is necessary to check the oil leakage. The leakage of hydraulic system generally occurs after a period of use. Seen from the surface phenomenon, it is mainly caused by the failure, damage, extrusion of the sealing element or the pulling of the sealing surface. The main reasons are oil pollution, improper roughness of sealing surface, unqualified sealing groove, loose pipe joint, increased clearance of mating parts, high oil temperature, deterioration of sealing ring or poor assembly, etc. Leakage is divided into internal leakage and external leakage. Usually, the fault is mainly caused by internal leakage.
