JLG 450A_AJ Series II Service Manual - Manual (Page 332)

SECTION 5 - HYDRAULICS
5-42 – JLG Lift – 3121180
5.5 PRESSURE SETTING PROCEDURE
Cold temperatures have a significant impact on pressure
readings. JLG Industries Inc. recommends operating
machine until 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.
Bang-Bang Main Relief
1. Install a high pressure gauge at port marked “M1”
located on front face of valve block.
2. Activate telescope in.
3. Adjust relief valve to 3300 psi (227.5 Bar), located on
front face of block, it’s the 5th relief valve counting
left to right. Turn clockwise to increase and counter-
clockwise to decrease.
Steer
1. Install a high pressure gauge at port marked “M3”.
2. Activate steer and adjust relief valve to 2500 psi (172
Bar). The relief valve is located on front face of block,
3rd relief valve counting left to right. Turn clockwise to
increase and counterclockwise to decrease.
Platform Level Up
1. Install a high pressure gauge at the port marked
“M2”, located on the platform valve block.
2. Activate level up to end of stroke. You should read
2800 psi (193 Bar).
3. The level up relief valve is located next to the check
port. Turn clockwise to increase and counterclock-
wise to decrease.
Platform Level Down
1. Install a high pressure gauge at port marked “M1”,
located on platform valve block.
2. Activate level down to end of stroke, reading 1800
psi (125 Bar).
3. The level down relief valve is located next to the
check port. Turn clockwise to increase and counter-
clockwise to decrease.
Articulating Jib
1. Install a high pressure gauge on port marked “M3”
on Jib block, located on platform valve block.
2. Activate Jib up or down. You should read 1500 psi
(103 Bar).
3. The relief valve is located on the Jib block. Turn clock-
wise to increase, counterclockwise to decrease.
Proportional Main Relief
1. Install a high pressure gauge at port marked “M2”,
located on front face of block.
2. Raise boom up to end of stroke, or remove hose
from port #10 and plug and cap, then activate lift up.
3. This valve should be adjusted to 3200 psi (220 Bar).
This relief valve is located on front face of block and is
the 4th relief valve counting left to right. Turn clock-
wise to increase, counterclockwise to decrease.
Lift Down
1. Install a high pressure gauge at port marked “M2”.
2. Activate lift down.
3. This relief valve should be adjusted to 1200 psi. The
relief valve is located on front face of block, and is
the 2nd relief valve counting left to right. Turn clock-
wise to increase, counterclockwise to decrease.
Swing
1. Left and right are done with (1) adjustment.
2. Install a high pressure gauge at the port marked
“M4”, located on the front face of the main valve.
3. Either remove (1) of the swing hoses, plug and cap
or swing turntable around until it hits the stop.
4. Activate swing. Pressure should be 1700 psi. The
relief valve is located on front face of block, the first
relief valve counting left to right. Turn clockwise to
increase, counterclockwise to decrease