Pressure Up Valve; Checks And Adjustments - Doosan DX140R Shop Manual

PRESSURE UP VALVE

Checks and Adjustments

This procedure should be done with two people. To reduce
the chance of accident or unintended start-up, one person
should remain at the operator's control stand while checks
and adjustments are made.
Vent hydraulic pressure from the reservoir to install an in-line "T-
style" adapter and test gauge (60 bar/1,000 psi) at the pilot
pump signal port relief valve outlet.
Start the engine and turn the engine speed dial to maximum.
When normal operating temperature is reached:
• Check pilot pressure and readjust it, if required:
• Select the Instrument Panel rear pump "pressure
display".
• Select Power Mode.
• Stall the boom cylinder (towards the extend side).
• Read rear pump pressure on the Instrument Panel
display.
Repeat all tests with and without "pressure up" selected through
the console rocker switch and joystick button.
If the two-stage main relief valve was not set correctly and main
relief high-stage pressure ("pressure up") is outside the
tolerance range, begin valve adjustment by loosening the
outside (widest diameter) lock nut on the relief valve. Turn the
adjusting screw clockwise
counterclockwise to decrease it. Pressure must be 350 bars
(5075 psi), or up to 10 bars (145 psi) higher.
Because one adjustment can affect the other, check low-stage
main relief pressure by repeating the cylinder stall test without
"pressure up." Readjust standard relief pressure by turning the
innermost (smallest diameter) screw clockwise to increase the
setting, or counterclockwise to decrease it. Pressure should be
at least 330 bars (4,785 psi), but less than 335 bars (4,858 psi).
IMPORTANT
Pressure adjustments and checks cannot be made if pilot
pressure is outside the specified range. Refer to the pilot
pump adjustment procedure if required, then proceed with
any necessary adjustments to main relief pressure settings.
Hydraulic System Troubleshooting, Testing and Adjustment
WARNING
to increase pressure, or
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