JLG 1850SJ Service Manual - Manual (Page 85)

SECTION 3 - CHASSIS & TURNTABLE
3121619 – JLG Lift – 3-43
3.13 SWING CONTROL SYSTEM
The swing control system uses the turntable swing angle sen-
sor in addition to the Drive Orientation System (DOS) proxim-
ity switch to prevent turntable swing while the axles are
retracted. Swing will be allowed to +/- 35 degrees (before the
DOS proximity switch trips) to facilitate positioning the turnta-
ble for transport of the machine. Attempts to swing past this
position will be disallowed by the control system and the
operator will be prompted via the LCD display in the platform
to swing in the opposite direction to return the boom behind
the rear wheels. Once the axles are extended the boom has
360 degree continuous turntable swing. If the turntable is
swung past +/- 35° when the boom is lowered into the trans-
port position, the operator will have to swing the turntable
back within the rear wheels before attempting to retract the
axles.
3.14 CHASSIS TILT INDICATOR SYSTEM
The Chassis Tilt Indicator System measures the turntable angle
with respect to level ground. The tilt sensor (mounted to a
bracket on the side of the turntable near the boom pivot pin)
has three settings; 3.0 side tilt, 5.0 omni directional tilt, and an
8.0 omni directional tilt.
The 5.0 omni directional angle setting is used for the purpose
of warning the operator by means of the chassis tilt light in the
platform display panel. Additionally when used in conjunction
with the Beyond Transport - Drive Speed Cutback System, the
tilt sensor will cause an alarm to sound and automatically put
all functions in the creep speed mode and drive will be cut
out. With the exception of the drive being cut out, this is a
warning system only indicating to the operator that the
machine has reached the out of level limit. The machine will
continue to function. The operator is responsible to prevent
the machine from attaining an unstable position.
The 3.0° side tilt setting is used in conjunction with the main
boom length and when exceeded, imposes the same func-
tionality as the 5.0° omni directional setting plus prevents
boom telescope out. The side tilt setting is ignored when the
main boom length is less than 1477.7 inches in the 500 lb
mode or 1442.8 inches in the 1000 lb mode.
The 8.0º angle is used exclusively for the purpose of automati-
cally shifting the drive motors to the maximum displacement
position (slow speed).
The control system responds to indicated angle readings 0.3
degree smaller than the required angles to account for calibra-
tion and sensor variation.
3.15 AUXILIARY POWER SYSTEM
The auxiliary power system is intended as a secondary means
of moving the boom in the event of primary power loss. This
system uses an electric motor/pump unit powered by two12V
batteries capable of operating all functions except drive, con-
trolled arc, controlled boom angle, and envelope tracking.
During main lift up or down functions, no other functions are
permitted and during main lift up functions, automatic plat-
form leveling is not active but jib leveling is active. To reduce
the demand on the battery and therefore extend the run time
of the system, the auxiliary power functionality differs from
the primary power functionality. The auxiliary power main lift
down function supplies pilot pressure to the main lift cylinder.
This allows gravity to lower the boom. The system redirects
discharge oil from the main lift cylinder to retract the main
telescope cylinder. At high main boom angles the envelope
may be encroached during lift down requiring the operator to
use main telescope in. When the main boom is retracted to the
transport length, the main telescope in valve is dropped out
and lift down is operated alone allowing the platform to reach
the ground. This not only greatly reduces the power required
for these functions but also lowers the boom within the enve-
lope regardless of starting position. Jib lift down function may
then be operated allowing the platform to reach ground level.
Envelope control and moment control remain active during
the auxiliary power function.