In the hydraulic transmission system and engine system software, wear and jam of all components are caused by abnormality of the excavator's posture, starting, engineering construction, etc., ranging from slow posture and lack of energy, severely holding the car and stopping the fire and slowing down more severely, only shutting down service.
Today, I will take everyone to take a look at a series of fault conditions caused by a relatively serious wear of a valve core, and the subsequent inspection and handling methods, hoping to give everyone a reference.
Failure condition:
According to the owner's account, the faulty excavator stopped the car and stopped when it was in the 3rd gear. When running at high speed, the speed of the equipment would be more serious and the speed would be reduced. However, this situation improved to a certain extent during cooling. Since the construction has been seriously endangered, the owner did not hesitate to immediately call in a technical engineer for repairs.
Failure analysis
Based on the above-mentioned fault conditions, the analysis is caused by the following levels of faults. Can carry out gradual maintenance.
1. The engine oil pump is worn out;
2. The high-pressure diesel pump of the engine is worn out;
3. The pump oil of the engine diesel engine is worn out;
4. EC-7 control board failure;
5. The hydraulic oil pump controller is stuck;
6. Wear of pilot pressure reducing valve
Troubleshooting
1. The first and easiest to check is the fuel pipe and filter element, and there is no abnormality. The fuel pipe and filter element are relatively clean. When the excavator is in a warm state, start the engine, the engine is very easy to start. Everything is normal at full load and acceleration, so the first step is to eliminate the engine oil pump, high-pressure diesel pump, and oil pump failures of this product.
2. People changed the motor control method to hydraulic control and removed the power circuit. They found that the fault still exists, or the speed of the hot car is more serious. Therefore, the faults in the motor control are eliminated, and the control board is also eliminated. problem.
3. Feed the feedback on the main pump controller to the oil pipeline, exchange parts, and do a single posture for trial operation. It is found that the engine will hold the car, and when it is used as a composition posture, the hold-up condition will decrease. No change from before, temporarily eliminate the main valve control board failure.
Then the barometer accurately measures the pilot working pressure when the equipment is at low standby speed. Check that the pilot is 22bar. All normal pilot working pressures should be around 35bar. Adjust the pilot pump safety valve. Regardless of the two adjustments, it is found that the working pressure has not increased. The safety valve of the pilot pump was disassembled, and it was found that the internal wear of the safety valve was relatively serious. Simple cleaning, polishing, and solution can no longer achieve the expected goal.
troubleshooting
Because the safety valve wears more serious and the gear oil is a bit dirty, the overhaul master suggested that the owner of the machine should remove and replace the new safety valve and gear oil, as well as the new pilot pump and hydraulic filter element.
After the disassembly and replacement, adjust the pilot working pressure, the speed of the excavator has become faster after debugging, and the hold-up phenomenon has also disappeared. Although it cost four to five thousand yuan, the rapid and accurate troubleshooting also robbed the owner of the construction time for the project.
summary
In fact, many troubles and problems are all ‘dragged’ out. Overhaul time is delayed, maintenance is postponed, and minor problems are found to be unsolved, until the equipment is completely paraded.
I also look forward to reminding everyone of the problem of the malfunction of the said equipment. If it is not so good, it must be solved as soon as possible. Don't let the trouble that can be solved by four or five hundred be delayed to four or five thousand before the repair is completed.
