Measurement of excavator overload performance

By applying an external force while blocking the return oil circuit from the control valve, the pressure in the oil circuit will inevitably increase. This measurement method is dangerous and the results obtained using this method are unreliable.

The pressure setting of the overload relief valve must be carried out at the specified oil volume (usually much smaller than the oil delivery volume of the main pump).

So, if the set pressure of the main relief valve can be reset to be higher than the set pressure of the overload relief valve, the main pump needs to supply a lot of oil in order to correctly measure the set pressure of the overload relief valve. Therefore, in order to accurately measure the set pressure of the overload relief valve, the overload relief valve unit must be removed from the machine and tested on the test bench

If it is necessary to test the performance of the overload relief valve on an excavator, in any case, when measuring the main relief pressure, each front-end function of the overload relief valve that needs to be measured should be overflowed. Also, if the measured pressure of the main relief valve is within the specified range, it can be considered that the overload relief valve is functioning properly.

The main pressure method for measuring front-end functions is as follows:

1. Select the following switch positions: Engine control dial: Fast/Slow E mode switch: OFF HP mode switch: OFF
Work mode selector: General purpose mode
2. Use the bucket, forearm, andBig armSlowly operate the control lever to the end of the stroke, allowing each function to overflow once.
3. When overflowing front-end functions, read the pressure on the pressure gauge.
4. Measure the bucket, forearm, and boom in sequence.
Measure each function three times and calculate its average value