JLG 1250AJP Service Manual - Manual (Page 406)

SECTION 5 - HYDRAULICS
5-52 – JLG Lift – 3121171
Adjustments Made at the Frame Valve Bank
AXLE EXTEND AND RETRACT, FRONT AND REAR -
2500 PSI (172.3 BAR)
1. To extend the axles, drive the machine back and
forth until extended. A machine that cannot be
driven must be jacked up.
2. On both the front and rear frame valve banks, install
a high pressure gauge on ports MA1 for extend and
MA2 for retract. The gauge should read 2500 psi
(172.3 Bar) in both directions.
3. The axle extend/retract cylinders are connected
hydraulically in parallel. In order to get the correct
pressure of the circuit being adjusted, unscrew the
solenoid coil from the circuit not being adjusted and
pull it away from the valve.
4. Turn clockwise to increase, counterclockwise to
decrease.
STEERING, FRONT AND REAR
NOTE: The following procedure requires 2 people to per-
form. One is needed for verifying / adjusting pres-
sure readings and wheel spindle alignment the other
for operating the steer functions and using the Ana-
lyzer from the platform.
The Analyzer is required to perform the pressure check
procedure through access of the calibration menu. The
calibration menu will allow for extending and retracting the
steer cylinders individually, verifying pressures, and
proper steer sensor calibration. Verification of the steer
sensor calibration will require one of two types of measur-
ing methods; using a square and ruler or using string as
explained in Section 6 - JLG Control System. The purpose
of these measuring tools is to assure that the wheel spin-
dle is aligned “straight” with the extended axle weldment.
1. Position the machine with both front and rear axles
fully extended.
2. Install the Analyzer in the platform control box and
scroll menu’s to Access Level 2 and insert password
(33271) to get into Access Level 1.
3. Scroll to the calibration mode. Once in the calibra-
tion mode, press “ENTER” and scroll to steer. Once
in the steer calibration mode, the Analyzer is going
to ask to calibrate the steer sensors, this is going to
allow extending and retracting each steer cylinder
individually during this process. The JLG control
system will ask to calibrate the left front sensor, the
left rear sensor, the right front sensor and finally the
right rear sensor in that order. During this calibration
mode each individual steer cylinder will be extended
and retracted to verify correct pressures with the
marked MS (Measure Steer) ports on the steer / axle
valve that pertains to that steer cylinder. Refer to the
Hydraulic Schematic in Section 7 - Schematics.