1. Standard pressure value of hydraulic system
2, safety valve pressure adjustment
(1) Stop the excavator on a level ground and turn off the fire.
(2) Release the pressure of the hydraulic system.
(3) Install a 4900kPa pressure gauge on the upper pump and lower pump pressure measuring joints
(4) Install a 490kPa pressure gauge on the power conversion connector.
(5) Start the engine, operate the stick joystick in full stroke, swing the stick cylinder in and out, until the hydraulic oil temperature reaches 55℃.
(6) The power mode selector switch is at position III, the engine throttle knob is at position 10, and the AEC switch is at the OFF position. Under no-load conditions, the engine speed is the rated speed, and write down the engine rated speed value.
(7) Adjust the pressure of the safety valve when the engine and the main pump are working normally. If the pressure adjustment result is not correct, check and adjust according to the characteristic curve of the engine and the main pump.
3. Adjustment of main relief valve pressure
Adjust the pressure of the main safety valve in order to adjust the pressure of each working device and travel safety valve.
(1) Stop the excavator on a level ground and turn off the fire
(2) Release hydraulic system pressure
(3) Check the set pressure of the main safety valve, it should be (31400±490)kPa
(4) Tighten the lock nut and turn the adjusting bolt clockwise until it is fully tightened, then tighten the lock nut
(5) Loosen the lock nut and turn the adjustment nut 1/4 turn clockwise, and then tighten the adjustment nut.
4, the currency adjustment of the secondary safety valve
(1) Preparation: Enable the check method in the maintenance service program to keep the power conversion pressure at 2250kPa. This value can be displayed on the pressure gauge or monitor at the pressure measurement point. During the pressure period of the safety valve, do not stop the engine. This can prevent the power conversion pressure from changing.
(2) Using the pressure gauge on the pressure measuring point of the upper pump, the opening pressure of the safety valve in the boom and bucket parking road can be read. Using the pressure gauge on the pressure measuring point of the lower pump, the opening pressure of the safety valve in the stick oil circuit can be read.
(3) Compare the opening pressure of the safety valves of the above working devices with the standard pressure, if they are inconsistent, adjust to the standard
(4) After adjusting the pressure of each safety valve, restore the opening pressure of the main safety valve to its original value.
According to the above methods and steps, adjust the pressure of the stick cylinder safety valve, bucket cylinder safety valve, and boom cylinder safety valve to make them consistent with the standard values in Table 4-13. After the pressure adjustment is completed, the verification method in the maintenance service program shall be used for verification.
5. Adjusting the pressure of the traveling crossover relief valve
(1) Enable the check method in the maintenance service program and keep the power conversion pressure at 250kPa3
(2) In order to prevent the power conversion pressure from changing during the activation of the calibration mode, do not turn off the engine.
(3) Insert the track pin into the track drive wheel to prevent the drive wheel from rotating in the forward direction
(4) Slowly move the left walking joystick to the forward position, and check the pressure gauge reading on the pressure measuring point of the lower pump, that is, the opening pressure of the walking cross relief valve
(5) Move the left walking joystick back to the neutral position. At this time, you can adjust the pressure of the walking cross relief valve, loosen the lock nut and turn the adjusting bolt until the pressure gauge reads (36800±1470)kPa.
(6) Tighten the lock nut, the tightening torque is (44±5)N·m
(7) According to the same method, adjust the pressure of the right travel cross relief valve
(8) Cancel the check method in the maintenance service program
6. Adjustment of the pressure of the rotary safety valve
The method of adjusting the pressure of the rotary safety valve is basically the same as the method of adjusting the pressure of the above-mentioned walking crossover relief valve. In the process of pressure measurement, for excavators with a swing lock pin, directly use the swing lock pin to lock the swing mechanism and load the hydraulic system; for the excavator without a swing lock pin, the swing brake can be used to lock the swing mechanism and load the hydraulic system .
