Extending Axles; Axle Limit Switch Adjustment Procedure - JLG 1200SJP Service And Maintenance Manual

SECTION 3 - CHASSIS & TURNTABLE

3.2 EXTENDING AXLES

The Axle Extension System allows each of the four axles to be
extended and retracted together while maintaining full steer-
ing control as the machine is driven. The system allows the
axles to extend or retract only while the boom is in the trans-
port position and in order to minimize wheel scrubbing during
axle movement, a minimum drive speed must be attained
before axle extension/retraction will be permitted. 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. 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 retract-
ing and will be on constantly when the axles are fully
extended. With the axles not fully extended, the boom is
restricted to operation within the transport position. If a signal
from any axle extend sensing switch is lost when the boom
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 automatically reduce the wheel angle to 25
degrees during axle retraction.
3-2
NOTE: For more detailed information concerning system adjust-

3.3 AXLE LIMIT SWITCH ADJUSTMENT PROCEDURE

Figure 3-1. Axle Limit Switch Adjustment
ment and operation, refer to Section 6 - JLG Control Sys-
tem.
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 (3.1 mm) from the edge
of the axle cutout. It may be necessary to reposition the
switch arm ±10° to accomplish this.
4. Ensure the arm will clear the axle (without bottoming
out to 70° stroke of the switch) in the retracted position.
5. Check for proper operation. Axle set light is to deacti-
vate when the axle is retracted 0.625 inches (16 mm)
maximum from fully extended.
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