JLG 1850SJ Service Manual - Manual (Page 44)

SECTION 3 - CHASSIS & TURNTABLE
3-2 – JLG Lift – 3121619
3.2 AXLE EXTENSION SYSTEM
NOTE: The boom must be oriented between the rear wheels to
extend or retract the 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 (see Transport Position Sensing System in Sec-
tion 4) 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 linear sensors (one at each axle) to sense when the axles
are fully extended. If any of the linear sensors detect an out of
range value for axle set, 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 retracting 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
(see Transport Position Sensing System in Section 4). If a signal
from any axle linear sensor 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 +/- 20 degrees anytime the
axles are not fully extended. If the wheel angle is more than +/
- 20 degrees when the axle retract command is engaged, the
control system will automatically reduce the wheel angle to 20
degrees during axle retraction.
3.3 DRIVE ORIENTATION SYSTEM
The Drive Orientation System (DOS) is intended to indicate to
the operator conditions that could make the direction of
movement of the chassis different than the direction of move-
ment of the drive/steer control handle. The system indicates to
the operator the need to match the black and white direc-
tional arrows on the platform control panel to the arrows on
the chassis for the intended direction of travel. The system
uses a proximity switch mounted on the hydraulic swivel, an
indicator light and an override switch on the platform display
panel. The proximity switch trips when the turntable is swung
+/- 35 degrees off center of the normal driving position. This
occurs roughly when the boom is swung past a rear tire. When
the turntable is in the normal drive position with the boom
between the rear tires, no indications or interlocks are made.
When the machine is actively driving when the turntable is
swung past the switch point, the system is ignored until drive/
steer is released. When drive is initiated with the boom swung
past the switch point, the DOS indicator will flash and the
drive/steer functions will be disabled. The operator must
engage the DOS override switch to enable Drive/steer (high
drive will remain disabled). When the DOS is enabled, the DOS
indicator will flash during the 3 second interval until the drive
function is selected. If the timer expires, the DOS override
switch must be re-engaged to enable drive/steer.