Service Manual Instruction Manual
SECTION 5 - HYDRAULICS
3121171 – JLG Lift – 5-47
5.7 PRESSURE SETTING PROCEDURE
Cold temperatures have a significant impact on pressure read-
ings. JLG Industries Inc. recommends operating the machine
until the hydraulic system has warmed to normal operating
temperatures prior to checking pressures. JLG Industries Inc.
also recommends the use of a calibrated gauge. Pressure read-
ings are acceptable if they are within ± 5% of specified pres-
sures.
To ensure all pressures are set correctly, the following proce-
dures must be followed in order.
1. All applicable steps in Section 5.10, Drive & Function
Pump Start Up Procedures must be followed.
2. Set up of the function pump.
3. Adjustments made at the main valve bank.
4. Adjustments made at the platform valve.
Set Up of the Function Pump
STAND BY PRESSURE OR LOW PRESSURE RELIEF - 450 PSI
(31 BAR)
1. Install a low pressure gauge at port MP1 of the main
valve block capable of reading 450 psi (31 bar).
2. Start the engine from the ground control. The gauge
should read 425-475 psi (29.3-32.75 bar).
3. To make an adjustment to this pressure, go to the
engine compartment, locate the function pump. The
stand by adjustment is the outside adjustment, closest
to the turntable.
4. To make an adjustment to this pressure on a Rexroth
pump, go to the engine compartment and locate the
function pump which is the back pump. The high pres-
sure relief adjustment is the adjustment closest to the
pump. Using a 17 mm wrench, remove the cover nut. Be
careful not to lose the o-ring washer inside the cover
nut. Loosen the jam nut at the setscrew with the 17 mm
wrench. Using a 3 mm allen wrench, adjust clockwise to
increase, or counterclockwise to decrease pressure.
To make an adjustment to this pressure on a Sauer
pump, loosen the 4 mm setscrew towards the engine.
Using a 6 mm allen wrench, turn clockwise to increase
pressure and counterclockwise to decrease pressure.
5. After adjusting the pressure, tighten the jam nut and the
cover nut if applicable.
6. Start the engine and verify the gauge reads 425-475 psi
(29.3-32.75 bar).
REXROTH PUMP
SAUER PUMP