The excavator boom movement is one of the most frequently used movements in the daily construction process. If the boom has problems such as slow lifting and weakness, it basically declares that it needs to be shut down for repair. Let's look at a case how to solve the slow and weak lifting of the arm!
Failure details:
A CAT 320D excavator, recently found that the excavator appeared to be unable to lift the boom slowly, please call to consult
Fault on-site inspection steps are as follows:
(1) Tooling inspection: Check whether the working device does not match the model.If it does not match, it will cause the boom to lift weakly and replace it.
(2) Visual inspection: Check the main branch of the main branch of the boom branch and the pilot branch of the boom for leakage outside.If the branch has oil traces leaking out of the system, it indicates that the failure of the boom lift is weak. The cause of oil leakage and eliminate it.
(3) Noise check: Check whether there is noise in the boom branch and the boom pilot branch.If there is noise, it indicates that there is a blockage or internal leakage in the branch.The reason should be investigated along with the noise and eliminated.
(4) Check the oil cylinder.If the control valve is in the neutral position after the oil cylinder is lifted, the boom will obviously descend automatically.It may be that the oil cylinder has a poor seal, the oil cylinder safety valve is not closed tightly, and the oil leakage of the oil pipe. Clear the cause and eliminate the symptom.
3. Confirm the cause of failure
Check the overflow pressure of the safety valve of the boom pipeline as follows:
(1) Increase the pressure of the main safety valve of the excavator by loosening the lock nut of the main safety valve and turning the adjustment screw clockwise one or half turn,
(2) Start the excavator, set the engine speed adjustment knob to the 10th position, and raise the boom to the state of holding the machine.
(3) By observing the pump pressure displayed by the monitor, it was found that the pump pressure was 35000KPa lower than 38000 + 1000-1500kpa to a normal value.
According to this, it can be concluded that the failure of the boom lift is caused by the pressure of the pipeline safety valve being set too low.
4. Reasons for maintenance failure
The steps to debug the overflow pressure of the safety valve of the boom pipeline are as follows:
(1) Loosen the lock nut on the pipeline safety valve;
(2) Rotate the adjustment nut clockwise to increase the set pressure of the pipeline safety valve (Note, the pressure change of the pipeline safety valve one turn is llOOOKPa, depending on the actual pressure of the pipeline and the expected pressure (38000 + 1000 -1500KPa) depending on the difference, rotate the angle of the adjusting nut)
(3) Lock the lock nut on the pipeline safety valve to 20 ± 2N.m;
(4) After adjusting the pipeline safety valve, adjust the pressure of the main safety valve back to 36000KPa. Circle, that is, the pressure of the safety valve can only be adjusted tightly, not loosely);
