The boom is falling too fast and “nodding†when the boom is raised. A "nodding" failure is usually a damage to the load check valve at the inlet of the control valve, but no problems were found after inspection. Combined with the system schematic analysis: the fault is a one-way valve failure between the boom control valve and its acceleration valve. Confirmed after dismantling.
Swing and right walk suddenly disappeared within a few minutes. The test vehicle found that the front pump outlet pipe vibrates strongly, and the fuel tank return filter has a large amount of copper iron. Copper iron is also present in the front pump housing. The front pump is seriously damaged.
Suddenly the whole car moves slowly, and the speed is 1/5 of the standard working speed. The engine is working properly. The fault is that the engine speed is damaged.
Suddenly the whole car movement "smashing the car", after inspection, found that the variable solenoid valve PCV of the rear pump does not work, because the connection between the solenoid valve and the computer board is often shaken due to the machine, the wire harness plug is loose, resulting in an open circuit.
The whole machine moves slowly and the hydraulic pump has abnormal noise.
Upon inspection, there is a large amount of paper dust on the filter screen at the pump suction port of the hydraulic oil tank. After cleaning, the whole machine works normally. After about 30 minutes of normal operation, the swing and right walk as well as the boom and stick are extremely slow. Other actions are normal.
After exchanging the main pump outlet tubing, the bucket and left travel are extremely slow, indicating that the fault is on the front pump or its variable mechanism. After cleaning the valves of the variable mechanism, the whole machine works normally.
Suddenly the bucket and left travel are extremely slow. After exchanging the main pump outlet tubing, the swivel and right travel and the boom and stick are extremely slow. After the inspection by the separation method, the fault is confirmed on the variable mechanism of the rear pump. The disassembly of the variable mechanism found that the pin of the variable piston fork fell. Normal after reinstallation.
After about 2 to 3 minutes of engine operation, the left walk slows down. The inspection found that the sound of the engine was boring when it was empty and seemed to work on load.
After testing the outlet pressure of the hydraulic pump, after the engine was started, the front pump no-load pressure was 1.3 MPa, and the rear pump no-load pressure was 1. ZMPa. However, after 2 to 3 minutes, the front pump no-load pressure is 1.3 MPa, and the rear pump no-load pressure is 30 MPa. According to the schematic analysis: after the pressure changes, the actuators have no action, and the pressure generated by the system can only come from the action of the backup valve. The fault disappears after removing the pilot control tube at both ends of the backup valve.
It is used for two years. It has been used for 3 years. After the purchase, it was found that the boom and lifting boom were slow during operation, and the others were normal. After inspection, the half-flow valve of the stick was artificially changed, and it was working normally after the original system was restored.
The crawler is weak and has no walking low gear. After replacing the seal of the central swivel joint, the fault remains. Checking the travel speed solenoid valve found that the spool was stuck due to dirt in the oil. Normal after cleaning.
Suddenly, the left side walked forward without, and the rest of the action was normal. Upon inspection, the overload valve of the left travel motor was lifted by the dirt from the valve core, resulting in no progress.
Swing and right walk suddenly disappeared within a few minutes. The test vehicle found that the front pump outlet pipe vibrates strongly, and the fuel tank return filter has a large amount of copper iron. Copper iron is also present in the front pump housing. The front pump is seriously damaged.
Suddenly the whole car moves slowly, and the speed is 1/5 of the standard working speed. The engine is working properly. The fault is that the engine speed is damaged.
Suddenly the whole car movement "smashing the car", after inspection, found that the variable solenoid valve PCV of the rear pump does not work, because the connection between the solenoid valve and the computer board is often shaken due to the machine, the wire harness plug is loose, resulting in an open circuit.
The whole machine moves slowly and the hydraulic pump has abnormal noise.
Upon inspection, there is a large amount of paper dust on the filter screen at the pump suction port of the hydraulic oil tank. After cleaning, the whole machine works normally. After about 30 minutes of normal operation, the swing and right walk as well as the boom and stick are extremely slow. Other actions are normal.
After exchanging the main pump outlet tubing, the bucket and left travel are extremely slow, indicating that the fault is on the front pump or its variable mechanism. After cleaning the valves of the variable mechanism, the whole machine works normally.
Suddenly the bucket and left travel are extremely slow. After exchanging the main pump outlet tubing, the swivel and right travel and the boom and stick are extremely slow. After the inspection by the separation method, the fault is confirmed on the variable mechanism of the rear pump. The disassembly of the variable mechanism found that the pin of the variable piston fork fell. Normal after reinstallation.
After about 2 to 3 minutes of engine operation, the left walk slows down. The inspection found that the sound of the engine was boring when it was empty and seemed to work on load.
After testing the outlet pressure of the hydraulic pump, after the engine was started, the front pump no-load pressure was 1.3 MPa, and the rear pump no-load pressure was 1. ZMPa. However, after 2 to 3 minutes, the front pump no-load pressure is 1.3 MPa, and the rear pump no-load pressure is 30 MPa. According to the schematic analysis: after the pressure changes, the actuators have no action, and the pressure generated by the system can only come from the action of the backup valve. The fault disappears after removing the pilot control tube at both ends of the backup valve.
It is used for two years. It has been used for 3 years. After the purchase, it was found that the boom and lifting boom were slow during operation, and the others were normal. After inspection, the half-flow valve of the stick was artificially changed, and it was working normally after the original system was restored.
The crawler is weak and has no walking low gear. After replacing the seal of the central swivel joint, the fault remains. Checking the travel speed solenoid valve found that the spool was stuck due to dirt in the oil. Normal after cleaning.
Suddenly, the left side walked forward without, and the rest of the action was normal. Upon inspection, the overload valve of the left travel motor was lifted by the dirt from the valve core, resulting in no progress.
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