In the hydraulic system, if only the boom lift is slow and weak, and the bucket is turned over normally. It is not difficult to see from the working principle diagram: the other work is normal, which means that the working pump and the main safety valve are working normally, and they provide enough pressure to the entire system, and it also shows the pipeline, oil filter and oil tank at the oil inlet of the pump The oil quantity and oil quality are no problem. At this time, it is only necessary to check the boom spool valve, boom cylinder, boom oil pipe, and their seals.
Inspection steps:
(1) Check the blockage of the oil circuit for routine treatment, remove the oil pipe, remove the arm spool valve body, stem and related parts for cleaning, clean the oil passage and blow dry with compressed air.
(2) Check the leakage of the oil circuit. The leakage of the hydraulic system is generally generated after a period of use. From the surface phenomenon, it is mostly caused by seal failure, damage, extrusion or the sealing surface is pulled. Oil pollution, improper sealing surface roughness, unqualified sealing groove, loose pipe joints, increased clearance of fittings, excessive oil temperature, deterioration of sealing ring or poor assembly, etc. Leaks are divided into internal leakage and external leakage, usually failure Mainly caused by internal leakage.
(3) Treatment of internal leakage failure The internal leakage in this part is mainly caused by the leakage in the boom spool and the cylinder. The internal leakage mainly occurs in the valve body and the cylinder and is not easy to check. However, we can use some auxiliary methods to judge the leakage.
(4) Inspection of the boom cylinder When the piston of the boom cylinder has received the bottom, remove the rod-less cavity oil pipe, so that the boom cylinder has a rod cavity to continue to fill the oil. If there is a large amount of working oil leaking out of the rod-less cavity oil pipe port, explain The hydraulic cylinder has internal leakage; it can also make the bucket full of load, lift to the limit position, the boom control lever is placed in the neutral position, and the engine is turned off, observe the boom sinking speed: Then, the boom control lever Put it in the ascending position, if the boom sinking speed is obviously accelerated at this time, it also indicates that the internal leakage occurs in the hydraulic cylinder; if the sinking speed does not change significantly, the cause of the internal leakage is the boom spool.
elimination method:
If the leak test result in the cylinder exceeds the specified value, it should be disassembled for further inspection. If the seal ring is damaged, replace it. If the cylinder wall is severely damaged, replace it: if the boom valve is seriously worn, replace it.
