JLG 1500SJ Service Manual - Manual (Page 422)

SECTION 5 - HYDRAULICS
5-70 – JLG Lift – 3121262
5.5 PRESSURE SETTING PROCEDURE
Cold temperatures have a significant impact on pressure
readings. 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 readings are acceptable if they are within
± 5% of specified pressures.
To ensure all pressures are set correctly, the following pro-
cedures must be followed in order.
1. All applicable steps in Section 5.8, 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.
5. Adjustments made at the jib valve.
Set Up of the Function Pump
HIGH PRESSURE RELIEF
1. Install a high pressure gauge at the MP port of the
main valve block.
2. Using a screwdriver, remove the Din connector from
the lift down coil.
3. Activate lift down. The gauge should read 3400 psi
(234.4 bar).
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
pressure 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 set-
screw with the 17 mm wrench. Using a 3 mm allen
wrench, adjust clockwise to increase, or counter-
clockwise 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. This is the maximum
relief pressure for all the functions governed by this
pump.
STAND BY PRESSURE OR LOW PRESSURE RELIEF
1. Install a low pressure gauge at port MP of the main
valve block capable of accurately reading 300 psi
(20.6 bar).
2. Start the engine, the gauge should read 300 psi
(20.6 bar).
REXROTH PUMP
SAUER PUMP