Hitachi EX200-3 has been used for more than 7000 hours, but it was discovered that the excavator suddenly went off-track during construction, and the forearm was also a bit problematic. The deviation of excavator walking is a commonplace problem for us old drivers. What causes the excavator to deviate? The excavator repair shop has analyzed the five major causes, and see which ones you know?
1. The safety valve of the walking motor leaks oil
The safety valve of the traveling motor will leak oil, which will cause the pressure in the system to be too low and the traveling motor will not rotate enough, which will cause the deviation of walking.
2. The movement of the main valve spool of the excavator deflected by the excavator is out of order
If the spring in the main travel valve becomes soft or broken, or the valve core is stuck, it may cause the oil pressure to drop and the travel deviation. During the inspection, the pressure of the main valve oil circuit should be measured. If the normal value is 30.5MPa, if the main valve is damaged, it needs to be replaced or repaired. We have encountered the deviation of the Daewoo DH220LC-V excavator. The result of the inspection is the main valve. Caused by damage to the ring, in the event of a running deviation fault, the first consideration should be whether the main spool has been damaged.
3. The travel suction valve on the deflection side of the excavator is damaged
The suction valve is installed on the hydraulic cylinder and motor of the working device. Its function is: when the hydraulic cylinder or motor is subjected to a huge impact from the outside, the abnormal high pressure in the hydraulic cylinder or motor can be removed. If the travel suction valve is damaged and the spring inside the valve is soft or broken, the oil pressure in the travel main valve will decrease, resulting in insufficient driving force of the travel motor and causing deviation.
4. The performance of the oil pump is degraded
When the excavator travels in a straight line, the plunger of one of the pump's pump flow regulators is stuck in a certain position, or due to severe wear and internal leakage, the system pressure can only reach 29.5MPa, which slows down the speed of the walking motor , The excavation opportunity occurs deviation.
5. The output pressure of the walking proportional valve on the deflection side of the excavator is too low
The proportional valve can output corresponding control oil pressure according to the length of the control stroke of the operating handle, thereby controlling the speed of the working device. Failure to change the filter element of the oil filter on time may cause the filter element to be clogged and the bypass valve of the oil filter to open, causing the spool valve in the valve to be blocked, and the control oil cannot flow through the rotary proportional valve on the deflection side of the excavator. To turn the main control valve, cause the walking deviation.
Conclusion: It is not uncommon during the construction process that a major failure is caused by a very small failure point, such as impurities in the hydraulic oil or diesel, rust in the pipeline, damaged joint seals, and blocked radiators, etc. Wait. More often, these small details can be avoided from daily observation of the condition of the machine, timely maintenance and replacement of maintenance parts. The last point is that when you encounter a malfunction, do not pay attention to the large parts for maintenance. These scattered and subtle points should also be observed! Only in this way can it be ensured that the excavator has fewer failures and prolongs its service life.
