Return to Master Table of Contents PRESSURE UP VALVE CHECKS AND ADJUSTMENTS Page 15 Hydraulic System Troubleshooting, Testing and Adjustment WARNING! 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 2-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 to increase pressure, or 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 inner-most (smallest diameter) screw clockwise to increase the setting, or counterclockwise to decrease it. Pressure should be at least 320 bars (4,641 psi), but less than 325 bars (4,714 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. Power Mode Operation Main Pressure and Tolerance Pilot Pressure and Tolerance Mode Neutral, No Operation 20 - 40 bar (290 - 580 psi) 30 bar + 10 bar (435 psi + 145 psi) Mode Cylinder Stall 320 bar + 5 bar (4,641 psi + 75 psi) 30 bar + 10 bar (435 psi + 145 psi) Mode W/ pressure Up Cylinder Stall 350 bar + 10 bar 5,075 psi + 145 psi 30 bar + 10 bar (435 psi + 145 psi)