Friends who have used excavators know that all components of the hydraulic transmission system and engine system software are worn and stuck, which can cause abnormalities in the excavator's posture, starting, and engineering construction. The posture can be slow and weak, and the car will be severely held. The speed of the fire break is more serious, only the shutdown is repaired.
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, as well as the subsequent inspection and handling methods, and look forward to giving everyone a reference.
Failure condition:
According to the owner's description, 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 call 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. Wear of the engine oil pump;
2. Wear of high-pressure diesel pump of engine;
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 speed up, so the first step can eliminate the engine oil pump, high-pressure diesel pump, and the product failure.
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 holding condition will decrease. No change from before, temporarily eliminate the main valve control board failure.
Then the barometer accurately measures the pilot working pressure of the equipment 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. No matter if you adjust it for two turns, you find 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 dismantle 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, after debugging, the speed of the excavator has become faster, 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.
summary
In fact, many troubles and problems were all ‘dragged’ out. Overhaul time was delayed, maintenance was postponed, and minor problems were found to be unsolved, until the equipment was 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.
