JLG 800A_AJ Service Manual - Manual (Page 318)

SECTION 5 - HYDRAULICS
5-36 – JLG Lift – 31208858
SECOND: Adjustments Made at the Main
Valve Block
MAIN RELIEF, STEER, SWING AND LIFT DOWN
1. Upper (main) lift down
Install a high pressure gauge at the "MP" port of the
main valve block. Activate upper lift down. The
gauge should read 1400 psi. The adjustment car-
tridge is located to the right of port #11. Turn clock-
wise to increase, counterclockwise to decrease.
2. Swing (left and right are done with one adjustment)
Using the same gauge at the same port, lock the
turn-table lock pin. Activate swing, the gauge should
read 1400 psi. The adjustment cartridge is located
on the right side of the block, the second relief valve
cartridge down from the top. (Note: the front of the
block has the bolt on valves on that face.) Turn
clockwise to increase, and counterclockwise to
decrease.
3. Steer
Using the same gauge at the same port. Activate
steer left or right. The gauge should read 1800 psi.
(2-wheel steer) both directions. One relief cartridge
is located on the right side of the block, at the top.
The other one is located on the left side next to port
#15. Turn clockwise to increase, counterclockwise
to decrease.
4. Platform Level Up
Install a high pressure gauge at port “M3”, located
on the right side of the block at the bottom. There is
pressure trapped at this test port. To release this
pressure, activate level down to the end of stroke
(the pressure in the up side goes to 0). This will
allow you to snap a gauge on this port. Activate level
up to the end of stroke, you should read 2600 psi.
This is what the pump high pressure valve is set at.
We want level up to read 2800 psi. The level up
relief valve is located in front of the “M3” gauge port.
When activating level up, and reading 2600 psi, turn
the adjustment counterclockwise until the pressure
drops below 2600 psi, turn clockwise (slowly) until
the gauge stops moving. It should stop at 2600 psi,
turn clockwise 1/2 turn and lock. This will give you
2800 psi on level up. This pressure is required to
keep the platform level when the boom is being low-
ered.
5. Platform Level Down
Install a high pressure gauge at the “M4” port
located on the left of the valve near the bottom. To
get a gauge on this point, activate level up to the
end of stroke (the pressure in the down side will go
to 0, allowing you to snap a gauge on). Activate level
down to the end of stroke, reading 1800 psi. The
level down relief valve is located on the right side of
the block above the “M4” port. Turn clockwise to
increase, and counterclockwise to decrease.
6. Tower Telescope Out
Install a high pressure gauge at gauge port "M2"
located on the right side of the valve block, at the
bottom. Activate tower telescope out, the gauge
should read 2200 psi. This can be done with the
tower lift down or up. If the tower lift is up, you must
run tower telescope out to the end of stroke. The
tower telescope out relief valve is located on the left
side, at the bottom, next to port #2. Turn clockwise
to increase, counterclockwise to decrease.
7. Articulating Jib Up
Install a high pressure gauge on the gauge port of
the jib block located on the top of the main valve
block. The gauge port has a 12" hose plumbed into
it for easy access. Activate jib up, you should read
2500 psi. The up relief valve is located on the right
side of the jib block toward the front. Turn clockwise
to increase, and counterclockwise to decrease.
8. Articulating Jib Down
Install a high pressure gauge on the gauge port of
the jib block located on top of the main valve block.
The gauge port has a 12" hose plumbed into it for
easy access. Activate jib down, you should read
1200 psi. The down relief valve is located on the
right side of the jib block toward the back. Turn
clockwise to increase, and counterclockwise to
decrease.
Figure 5-32. Articulating Jib Boom Pressure adjust.