A 3800-hour Caterpillar cat324 excavator's boom descends slowly, and it's difficult to support the car. Other actions of the excavator are normal.
Cat 324 excavator's boom descends slowly and cannot support the car. The test data is as follows:
1. Boom drop overflow pressure: 260 kg.
2. High pressure: 330 kg (other actions except for lowering the boom);
3. Pump control pressure: 33 kg (other actions except for lowering the boom);
4. Pilot pressure: 40 kg.
5. The second pilot pressure of the boom lowering: 38 kg.
6. Boom down pump control pressure: 15 kg.
Failure analysis:
Because the -5 pump control is caused by the valve stem cutting off the neutral oil passage, it is estimated that the boom stem fails to fully open. The boom drops the second pilot pressure: 38 kg. The pilot pressure is sufficient but the boom stem cannot be fully opened? It may be that the valve stem is stuck in one direction by foreign objects (because the boom is raised normally, so it is stuck in one direction). Because the boom is lowered to work for a single stem, the main stem works, in addition, the main stem contains a One-way valve, so, the most likely cause is that the plug of the one-way valve falls off, resulting in this failure caused by the stem cannot be fully opened. The boom stem plug is loose and blocks the stem from fully opening.
Knowledge supplement:
What is the problem with the weak arm of the Cat 324 excavator?
Analysis: Main safety valve failure. Hydraulic cylinder failure. Oil port safety valve failure will also cause the failure phenomenon of the excavator's small arm. The mismatch of hydraulic system pressure, flow rate and data causes the failure phenomenon of the excavator's small arm.
