Troubleshooting of crane

During the use of a QY25 truck crane, the main hoisting mechanism makes noise and the lifting is weak (the 6-fold wire rope cannot be hoisted when the weight is 16t).

There is a noise in the lifting mechanism. According to observation and analysis, the fault may lie in the balance valve. The valve is imported from Italy. Its remote control interface is equipped with a one-way damping combination valve (the damping is adjusted by thread). The principle is to open slowly (with a delay of 2s) and return oil quickly. The balance valve protects the lifting mechanism more safely. The cause of the failure may be that due to long-term use, the hydraulic system is not maintained in time, and there is a little oil in the damping part, which increases the damping, resulting in a longer opening delay (about 8s), causing the balance valve to open and the lifting brake to open incompatible When the sound of dangling and dangling teeth is made, the balance valve is removed for cleaning, assembly and adjustment, the delay reaches the factory requirements, and the malfunction disappears.

Weak lifting. The reasons are generally: the hydraulic motor drains too much oil, the volumetric efficiency is obviously reduced, and the lifting is weak; the control element overflow valve (pilot type) drains the oil, and the system pressure cannot rise, and the lifting is weak. Remove the motor drain port and operate the lifting mechanism to observe that the amount of oil drain is normal; remove the lifting relief valve (cartridge type) of the upper car valve group and check that one O-ring is slightly damaged, which leads to oil drain. The pressure can't go up. After replacing the O-ring, adjust the pressure to reach the design value. The crane was re-tested and the work returned to normal