JLG 800A_AJ ANSI Service Manual - Manual (Page 310)

SECTION 5 - HYDRAULICS
5-30 – JLG Lift – 3120740
MACHINES S/N 0300121643 TO PRESENT
1. Set Stand by pressure or load sense pressure.
a. Install a low pressure gauge at port “MP” of the
main valve block. A gauge capable of reading
400 psi.
b. Remove the wires from the upper lift (main lift),
valve coils on the main valve block. Start the
engine and activate upper lift up or down. Hold
the function for 10-15 seconds. This bleeds the
air out of the sense line. The gauge should be
reading 400 psi. (+40 -0 psi). To make an adjust-
ment to this pressure, go to the engine compart-
ment, locate the function pump.
c. There are (2) adjustments at the top of the
pump. They are located on the pump compen-
sator which has (4) bolts mounting it to the
pump. The stand by adjustment is at the top.
d. To adjust this, a 4 mm and 6 mm Allen wrench
will be needed. The adjustment screw is facing
the front of the pump, or toward the engine.
First, using the 4 mm wrench, loosen the set-
screw on the side of the compensator (facing
you) which is in line with the adjustment screw.
This is a jam nut screw which holds the main
adjustment from turning. Loosen it 1 turn. Then
using the 6 mm wrench adjust the main adjust-
ment clockwise to increase or counter-clockwise
to decrease. The pressure should read between
400-440 psi.
2. Set High pressure relief
a. Install a high pressure gauge at the “MP” port of
the main valve block.
b. Activate upper (main) telescope in. The gauge
should read 2600 psi.
c. To make an adjustment to this pressure, go back
to the engine compartment to the function
pump. The high pressure relief adjustment is the
lower one of the (2) on the compensator. To
adjust this, a 4 mm and 6 mm Allen wrench will
be needed. The adjustment screw is facing the
front of the pump, or toward the engine.
d. First, using the 4 mm wrench, loosen the set-
screw on the side of the compensator (facing
you) which is in line with the adjustment screw.
This is a jam nut screw which holds the main
adjustment from turning. Loosen it 1 turn.
e. Then using the 6 mm wrench adjust the main
adjustment clockwise to increase or counter-
clockwise to decrease. This is the maximum
relief pressure for all functions governed by this
pump.
LS adjustment screw
6mm
LS set screw
4mm
7-11 N•m [6-8 lbf•ft]
Case drain port L1
0-10 bar [0-100 psi]
7/8-14
3/8 in
54-136 N•m
[40-100 lbf•ft]
Gauge port M2
0-300 bar [0-5000 psi]
9/16-18
1/4 in
34-68 N•m
[25-50 lbf•ft]
M14
6mm
27-35 N•m
[20-26 lbf•ft]
LS/remote PC
signal port X
Figure 5-25. Load Sensing Control Adjustment
PC adjustment screw
6mm
PC set screw
4mm
7-11 N•m [6-8 lbf•ft]
Case drain po rt L1
0-10 bar [0-100 psi]
7/8-14
3/8 in
54-136 N•m
[40-100 lbf•f t]
Gauge port M2
0-300 bar [0-5000 psi]
9/16-18
1/4 in
34-68 N•m
[25-50 lbf•ft]
M14
6mm
27-35 N•m
[20-26 lbf•f t]
Figure 5-26. Pressure Compensation Control
Adjustment