JLG 150HAX Service Manual - Manual (Page 108)

SECTION 5 - HYDRAULICS
5-12 – JLG Lift – 3120817
5 Stack Directional Control Valve (External
Relief Adjustment Screws)
NOTE: Make all pressure adjustments with pressure gauge
plugged into quick-connect adjacent to high drive
dump valve at rear of valve compartment.
1. Main Relief.
a. Locate the Tower Lift Down Relief Valve. Screw
the adjustment screw in all the way.
b. Activate Tower Lift Down function. The gauge
should read 3800 psi (262 bar). If the pressure
gauge reads 3800 psi (262 bar), reset the tower
lift down relief to 3000 psi (207 bar).
c. If the pressure gauge does not read 3800 psi
(262 bar), the main relief cartridge will have to be
replaced as follows.
d. Turn off the engine and apply a vacuum to the
hydraulic tank.
e. Remove the main relief cap.
f. Remove the springs and relief cartridge.
g. Install a new relief cartridge and springs and
install the main relief cap.
h. Remove the vacuum from the hydraulic tank and
retest the main pressure reading.
2. Main Telescope Relief.
a. Bottom out Main Telescope Out function.
b. Adjust pressure to 3000 psi (207 bar).
c. Bottom out Main Telescope In function.
d. Adjust pressure to 3300 psi (228 bar).
3. Main Lift Relief.
a. Tower boom section must be fully raised to
operate Main Lift Up and Main Lift Down func-
tions.
b. Bottom out Main Lift Up function.