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Excavator Drivers Must Master These Excavator Maintenance Knowledge


SAFELY lists some fault examples here for readers' reference. Some of these faults may be difficult to see, but their judgment method may be enlightening to you.

[1] A Hitachi EX200-3 suddenly appeared the motion jitter of the whole vehicle, but only appeared when the excavator chassis was slightly tilted. If the excavator worked on the ground, everything was normal. When the first day heard the report, I could hardly believe my ears. After driving to the scene, I observed that the working site of the machine was an excavated ditch, and the fault phenomenon was as the report said.

After the test machine found that the machine chassis tilt jitter, once the excavator opened to the smooth working surface, the jitter stopped immediately. This is repeated many times. EX-Docder shows that jitter A is sometimes larger or smaller, and A is normal without jitter. External components check all in good order. It was getting late, and it was agreed that Japan should be fought again.

Arrived at the scene on the next day, check from the wire harness first, because of the analysis on the night before: there is no problem in each component, whether the problem lies in the bad contact of the line. First, the wire harness near the hydraulic pump was examined. It was found that the steel clip at the bottom of the hydraulic pump used to hold the wire harness of sensor A and other components had worn out the wire, exposing the copper wire.

When the chassis is tilted, the steel clip is in contact with the copper wire, resulting in a short circuit. And because of the vibration of the hydraulic pump, the two are connected and broken, which causes the jitter of the action; When the chassis is sitting, the distance between the two is far away and cannot be contacted. So it works fine.

[2] A Hyundai R290LC, working hydraulic system oil temperature is very high. The detection system found that the no-load pressure of the rear main pump was 10Mpa, the load pressure of the engine reached the rated transfer time and space was more than 20Mpa, and the actuator speed of the rear pump side was full when working. Analytical studies suggest that this phenomenon is contradictory.

First, check the no-load high voltage problem; The multi-way valve on the back pump side is not stuck in the middle. It is easy to appear that the spare valve with the valve stem not in the middle is on the front pump side, which has nothing to do with this. It is understood that the hydraulic main pump has been overhauled not long ago, so it is suspected that the variable fork of the rear main pump may trip and shift, resulting in the swash plate at a smaller displacement position. This can explain the problem of full speed. Why is the pressure higher at smaller displacement?

Decomposition of the main pump, it is found that the variable fork trip shift, resulting in the swash plate in a small displacement position. Due to insufficient fastening force and no specified thread locking glue. After repair, there is still no load high voltage phenomenon. By analyzing the hydraulic system diagram, it is found that the biggest cause of no-load high pressure of the rear pump is the logic valve of port B. If there is extra signal pressure of port B when there is no load, the main circuit can be cut off to cause high pressure.

Loosen and release the signal tubing of port B, start the engine and check, there is still high pressure. After studying the logic valve structure, it was found that there was a filter at the back of the throttle valve. After disassembly, it was found that the filter had been blocked by foreign bodies. After removal, it was installed and tested, and everything was normal.

[3] A Caterpillar 345B, working gap welding boom part, welding lapping part in the rotary platform, and disconnect the main switch of power supply. Start the engine after the end, the engine will automatically shut down after running for about 1 minute, and then start again, the engine does not work, but the starter works normally.

High-pressure common rail jet engine, model XX

Check the fault code: No exception.

[4] A Komatsu PC200-5, which is the second mobile phone. The owner of the machine reported that the bucket rod recovered slowly after the machine was bought.

After test, all parts are normal except the bucket rod is slow to recover. Generally speaking, if it should be accompanied by arm, bucket, walking or arm, rotation, walking full phenomenon. By comparing the hydraulic system diagram, it is found that Komatsu is different from other companies. There is a solenoid valve called bucket rod half flow valve in its loop, which is specially used to switch the single main pump or double main pump when the bucket rod is recovered.

Check the solenoid valve, do the bucket rod back when the electrical signal works normally, the solenoid valve outlet without oil. Decomposing the valve, it was found that the tubing of port P, T and A of the valve was installed in reverse, and the confluence of the double pump became the flow rate of the single pump during normal operation. So the action is full. Test machine after correct installation of P, T and A tubing, bucket rod retracting action is normal.

Observing the machine after maintenance, it was found that there were English "crane style" words on the body, indicating that it had been used for lifting work. It may be used for crane work in A Japanese company, deliberately refit the bucket rod reclaiming action to make it full, so as to adapt to the fine-tuning action when lifting.

[5] A Hitachi EX300-5 suddenly turned slowly, and found that there was no walking high and low gear and automatic throttle of the whole car.

Reason: the hydraulic oil at the outlet of the pilot filter element is close to the five-rod multi-way valve, which is used to provide the pressure oil of the rotary brake and the signal oil of the auto throttle of the whole vehicle. The joint at the inlet has a screen, which is blocked to make the pressure at the above two places extremely low.

[6] A Hitachi EX200-5, suddenly no way down gear, only high gear. Reason: There is a filter screen in the high and low gear of the walking motor. After blocking the filter screen, the oil in the variable piston of the walking motor cannot be released back to the oil tank. When the variable piston works, the displacement of the walking motor is the minimum, so it is always in high gear.

[7] A Hitachi ZAXIS330 suddenly suffocated, the reason being that the pilot filter element was blocked.

[8] For one Kobelco SK230-6, the user reported a sudden deviation of running. After inspection, not only the deviation of running, but also the full speed of one pump side was weak. Note Points that reflect machine faults are true and comprehensive. Cause: A pump-controlled solenoid valve has increased resistance.

[9] A Kobelco SK230-6, the instrument sometimes alarm, show pump control solenoid valve failure, the reason: hydraulic pump below the wire tube card wear copper wire leakage.

[10] A Hitachi EX200-1 was unable to walk on the left, because the front check valve of the left multi-way valve was damaged

[11] A Hitachi EX200-1, walking on the right is full, unable to move the arm bucket rod bucket is full, the reason: there is a piece of metal stuck in the right multi-way valve side walking check valve.

[12] A Sumitomo SH200-1 suddenly ran to the left. Reason: solenoid valve in the spool stuck stagnation, stay in the working position, cut off the normal pump feedback pressure, so that the pump cylinder swing Angle minimum. So part of the action becomes full.

[13] A Hitachi EX300-1 suddenly sank for a period of time when lifting in the air, and then rose again. The reason was that the load check valve of boom stem 2 in the multi-way valve was damaged.

[14] A Sumitomo SH200-1 suddenly did not move, the reason: the pilot solenoid valve coil was burned.

[15] There are multiple alarms on the instrument panel of a Kobelco SK200-5, cause: generator damage

[16] For a Hitachi EX200-3, there was oil pressure on the dashboard, charging alarm, and the engine could not be shut off. After the engine stopped, the power could not be cut off with the key, cause: the generator was damaged.

[17] A Sumitomo SH200-1, the speed of the whole car is very full, cause: the control pilot oil solenoid valve is damaged.

[18] ONE side of a Kobelco SK200-5 is full of weakness, cause: one valve of the solenoid valve set at the lower part of the driver's cab is damaged.

[19] A Sumitomo SH200-1 was reported in the morning to check the normal hydraulic circuit. It is understood that there was fog humidity last night, suspected air filter intake problem, the owner of the machine even yesterday afternoon just changed the new product, there can be no problem. After a strong request to remove the air filter test machine, everything is normal. That air filter quality is not good. When the air humidity is high, the paper expands and blocks the filter holes.

[20] A Sumitomo SH200-1, after replacing handok hydraulic pump assembly, one side of the pump acted as a brake, and other maintenance personnel replaced the regulator spring of one side of the pump, which worked normally after the original product was replaced. It shows that sometimes the characteristics of P - Q curve are different.


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