JLG 1850SJ Service Manual - Manual (Page 237)

SECTION 5 - BASIC HYDRAULIC INFORMATION & HYDRAULIC SCHEMATICS
3121619 – JLG Lift – 5-67
5.5 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. Setup of the Function Pump
PRESSURE COMPENSATOR (PC) SETTING
1. Install a high pressure gauge 5000 psi (345 bar) at the
“MP” port of the main valve block.
2. Remove the Deutsch connector from the lift down coil.
3. Activate lift down. The gauge should read 4000 psi. (275
bar).
4. To make an adjustment to this pressure, go back to the
engine compartment to the function pump which is the
rear pump. The high pressure relief adjustment is the
adjustment closest to the pump case.
5. Loosen the locking set screw at the side of the adjust-
ment. Adjust the PC to obtain 4000 psi (275 bar), clock-
wise increases pressure.
6. After adjusting the pressure, tighten the locking set
screw, and reconnect the Lift Down coil.
STAND BY PRESSURE OR LOAD (LS) SENSE PRESSURE
1. Install a low pressure gauge at port “MP” of the main
valve block. The gauge must be capable of reading 300
psi (21 bar).
2. Start the engine, the gauge should read 300psi (21 bar).
3. To make an adjustment to this pressure, go to the
engine compartment, locate the function pump.