JLG 1250AJP Service Manual - Manual (Page 51)

SECTION 3 - 1CHASSIS & TURNTABLE
3121171 – JLG Lift – 3-3
3.2 AXLE EXTENSION SYSTEM
The Axle Extension System allows each of the four axles
to be extended and retracted together while maintaining
full steering control as the machine is driven. The system
allows the axles to extend or retract only while the boom is
in the transport position (see Section 4.2, Transport Posi-
tion Sensing System) and in order to minimize wheel
scrubbing during axle movement, a minimum drive speed
must be attained before axle extension/retraction will be
permitted.
To extend/retract the axles, the user engages the axle
extend/retract switch on the platform console and the
drive control at the same time. The axle set indicator will
be off when the axles are not fully extended and the axle
extend/retract switch is not engaged. It will flash while the
axles are extending or retracting and will be on constantly
when the axles are fully extended.
The system uses four limit switches (one at each axle) to
sense when the axles are fully extended. If any of the
switches are not made, the control system considers the
axles retracted.
With the axles not fully extended, the boom is restricted to
operation within the transport position (see Section 4.2,
Transport Position Sensing System). If a signal from any
axle extend sensing switch is lost when the boom is
beyond the transport position, the axle set indicator will
flash and drive/steer functions will be disabled until the
boom is brought back into the transport position. The
steering angle will be automatically limited to ± 25
degrees anytime the axles are not fully extended. If the
wheel angle is more than ± 25 degrees when the axle
retract command is engaged, the control system will auto-
matically reduce the wheel angle to 25 degrees during
axle retraction.
NOTE: For more detailed information concerning system
adjustment and operation, refer to Section 6 - JLG
Control System.
3.3 AXLE LIMIT SWITCH ADJUSTMENT
PROCEDURE
1. Fully extend the axles.
2. Initially position the limit switch arm straight.
3. Select the mounting plate bolt pattern to position the
switch roller within 0.125 inches (mm) from the edge
of the axle cutout. It may be necessary to reposition
the switch arm ±10° to accomplish this.
Figure 3-1. Axle Limit Switch Adjustment