When the excavator is not working, after the outrigger is retracted, the outrigger gradually falls under the action of self weight.
1. Cause analysis
According to the structure and working principle, there is no locking device (hydraulic control check valve) on the outrigger in order to ensure the support function of the outrigger and prevent the risk of losing stability of the excavator under operation. When the slide valve of the control valve is in the middle position, in addition to the control valve itself closing the oil circuit in the front and rear cavities of the outrigger oil cylinder, the conical piston presses the valve sleeve tightly due to the action of the spring in the outrigger check valve, so that the two cavities of the oil cylinder are strictly sealed, so it plays a dual role in closing the oil circuit in the two cavities of the outrigger oil cylinder. If the piston sealing element is worn or damaged, the seal of the cylinder cover is damaged, and the one-way valve of the locking device is not tightly closed, the two cavities of the outrigger cylinder will leak oil to each other, resulting in the automatic lowering of the outrigger.
(1) The cylinder cover and piston sealing element are damaged. The piston sealing element is damaged because it is scratched by the cutting groove processed at the cylinder port during assembly, or worn for too long, resulting in radial compression deformation and loss of sealing, resulting in leakage.
(2) The locking device is not tightly locked, and the valve core of the locking device is stuck in the open position due to the mechanical impurities mixed in the oil during use or the mechanical impurities remaining in the locking device during processing; Or mechanical impurities stick to the one-way valve seat, so that the one-way valve is not closed tightly. At the same time, it will accelerate the wear of the piston and make the locking device not locked tightly. Here, the decrease of spring fatigue force will also cause the one-way valve to close loosely and affect the locking of the locking device.
2. Diagnosis and troubleshooting
During diagnosis, disassemble, check and diagnose according to the causes analyzed above, and eliminate the symptoms.
