JLG 800A_AJ Service Manual - Manual (Page 311)

SECTION 5 - HYDRAULICS
3120858 – JLG Lift – 5-29
Slave Cylinder Installation
1. Remove fittings from old cylinder and install in new
slave cylinder. Plug the port block holes in the old
cylinder with the plugs removed from the new cylin-
der.
2. Position the new cylinder in place using suitable
slings or support. Align barrel end mounting holes
with main fly holes.
3. Using a suitable plastic or rubber hammer, drive the
barrel end attach pin into place and install retaining
hardware.
4. Remove caps from hydraulic hoses and attach
hoses to proper cylinder port.
5. Using auxiliary power, extend the slave cylinder rod
until the rod attach pin hole aligns with those in the
platform pivot. Using a suitable plastic or rubber
hammer, drive the pin in place and install the retain-
ing hardware.
6. Remove sling from the slave cylinder and support
from platform.
7. Using all applicable safety precautions, start the
machine from the ground control and fully raise and
lower the upper boom through several cycles to
bleed the platform level hydraulic circuit.
DO NOT OPERATE THE PLATFORM LEVEL SWITCH FROM THE
PLATFORM CONTROL CONSOLE TO BLEED THE SLAVE CYLIN-
DER. A PLATFORM UPSET MAY OCCUR.
8. Check for proper operation and for hydraulic leaks.
9. Check the fluid level of hydraulic tank and adjust if
necessary.
5.8 HYDRAULIC PUMP W/HAYES PUMP
DRIVE COUPLING LUBRICATION
Any time pump or pump drive coupling is removed coat,
pump and drive coupling splines with Lithium Soap Base
Grease (TEXACO CODE 1912 OR EQUIVALENT) coupling
is greased prior to assembly.
5.9 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.
FIRST: Set Up the Function Pump
(the pump that is mounted on the back of the drive pump).
MACHINES PRIOR TO S/N 0300121643
1. Stand by pressure or load sense pressure.
Install a low pressure gauge at port “MP” of the
main valve block. A gauge capable of reading 400
psi. Remove the wires from the upper lift (upper 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 adjustment to this pres-
sure, go to the engine compartment, locate the vari-
able pump. There are (2) adjustments at the top of
the pump. The stand by adjustment is at the top.
Using a 17 mm wrench, remove the cover nut. Be
careful not to lose the “o” ring washer inside the
cover nut. Loosen the jam nut at the set screw with
the 17 mm wrench. Using a 3 mm allen wrench
adjust clockwise to increase, or counterclockwise to
decrease. After adjusting the pressure, tighten the
jam nut and replace the cover nut. Reconnect the
wires on the upper lift coils.
2. High pressure relief.
Install a high pressure gauge at the "MP" port of the
main valve block. Activate upper (main) telescope
in. The gauge should read 2600 psi. To make an
adjustment to this pressure, go back to the engine
compartment to the variable pump. The high pres-
sure relief adjustment is on the lower one of the (2).
Repeat the same procedure as setting the stand by
pressure. This is the maximum relief pressure for all
functions governed by this pump.