Main overflow valve malfunction leads to low hydraulic system pressure

A user reported that the entire vehicle is moving slowly and powerless. Check the source of the fault. There were alarms for W001/F023 at 6HR and 75HR, and the after-sales service diagnostic data showed that the P1/P2 pump pressure could only reach around 21MPa when operating various actions to overflow. The display screen showed no alarms, and other sensors and solenoid valves reflected normal values.

At the same time, when the small arm of the machine is being recovered, the operation of the large arm lifting is particularly slow; B. C adjustment cannot be completed; During the boosting operation, the solenoid valve can operate normally but there is no change in the pressure value.

That's rightexcavating machineryPerform inspection:

1. Confirm that the alarm for WOO1 (rotation P/B release)/F023 (rotation brake solenoid valve disconnection) is not directly related to the fault phenomenon. Eliminate the low pressure caused by the above alarms.
2. Remove the plug of the P1/P2 unloading proportional valve, cancel the precise flow control, and check that there is no significant change in the load pressure value of the P1/P2 pump during overflow;
3. Adjust the opening pressure of the main overflow valve to a maximum of 21.7MPa and a minimum of 17.8MPa;
4. Check the service diagnosis N0.31-33 BOOM/ARM/BUCKET pressure values and feedback values of actuating electrical components, and there is no fault phenomenon.
5. Consider the cause of the main overflow valve malfunction:
Can only adjust to low pressure, not to high pressure;
When the forearm and upper arm are operated simultaneously, the upper arm hardly moves (internal leakage)
B. C adjustment cannot be completed
Determine the internal fault of the main overflow valve

The fault condition disappeared after replacing the main overflow valve.