Pressure setting procedures, Main valve hydraulic schematic -15 – JLG 4394RT Service Manual User Manual
Page 139
SECTION 4 - HYDRAULICS
3121133
– JLG Lift –
4-15
Pressure Setting Procedures
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.
1.
Install pressure gauge at the MP1 port.
2.
Adjust both Steer Section Crossover Relief’s all the
way in.
3.
Adjust Main Relief Cartridge out several turns.
4.
Activate engine and allow hydraulic system to come
up to operating temperature.
5.
Bottom out Steer function. Adjust Main Relief to
3000 psi (207 bar).
6.
Bottom out Steer Right and Steer Left functions and
adjust each Steer Crossover Relief to 2800 psi (193
bar).
7.
Bottom out Lift Up functions and adjust Lift Pressure
to 2700 psi (186 bar).
8.
De-energize Lift function, shut down motor, and dis-
connect pressure gauge.
Figure 4-16. Main Valve Hydraulic Schematic