JLG 1250AJP Service Manual - Manual (Page 241)

SECTION 4 - BOOM & PLATFORM
3121171 – JLG Lift – 4-1
SECTION 4. BOOM & PLATFORM
4.1 PLATFORM CONTROL ENABLE SYSTEM
The platform controls make use of a time dependent
enable circuit to limit the time availability of "live" or
enabled controls. To operate any directional function, the
footswitch must be depressed before activation of the
function. When the footswitch is depressed, the controls
are enabled and the operator has 7 seconds to operate
any function. The controls will remain enabled as long as
the operator continues to use any function and will remain
enabled 7 seconds after the last function has been used.
While the controls are "live", the enable light will be illumi-
nated in the platform display panel. When the time limit
has been reached, the enable light will turn off and the
controls will be "dead" or disabled. To continue use of the
machine the controls must be re-enabled to start the timer
system over again. This is done by releasing all functions,
then releasing and re-depressing the footswitch.
NOTE: For more detailed information concerning system
adjustment and operation, refer to Section 6 - JLG
Control System.
4.2 TRANSPORT POSITION SENSING
SYSTEM
The Transport Position Sensing System uses the following
sensors to sense when the boom is in the position associ-
ated with high speed travel.
• Main boom angle sensors (mounted at the tower to
main boom pivot pin)
• The main boom angle limit switch will be used in the
event of a main boom angle sensor fault
• Four main boom length limit switches (mounted on the
main base boom)
• Tower lift cylinder angle sensor (mounted at the tower
lift cylinder pivot to the turntable)
• The tower angle sensors in conjunction with the chas-
sis tilt sensor will be used in the event of a tower lift cyl-
inder angle sensor fault
• Tower boom length sensors (mounted in the pivot end
of the tower base boom)
• The tower length switch will be used in the event of a
tower length sensor fault.
• The position of the articulated jib is not considered
This system is used in the control of the following sys-
tems:
• Beyond Transport - Drive Speed Cutback System
• Drive/Steer - Boom Function Interlock System - CE
Only
• Jib Stow System
• Electrical Retrieval System
• Swing Speed Proportioning System
• Axle Extension System
• Oscillating Axle System
NOTE: For more detailed information concerning system
adjustment and operation, refer to Section 6 - JLG
Control System.
4.3 BEYOND TRANSPORT - DRIVE SPEED
CUTBACK SYSTEM
When boom is positioned beyond the transport position
as described in Section 4.2, Transport Position Sensing
System, the drive motors are automatically restricted to
their maximum displacement position (slow speed). See
Section 3.22, Chassis Tilt Indicator System for interaction
with the tilt sensor.
NOTE: For more detailed information concerning system
adjustment and operation, refer to Section 6 - JLG
Control System.
4.4 DRIVE/STEER – BOOM FUNCTION
INTERLOCK SYSTEM (CE ONLY)
The Drive/Steer – Boom Function Interlock System uses
the Transport Position Sensing System to sense when the
boom is out of the transport position. All controls are
simultaneously functional when the booms are within the
transport position as on the standard machine. When the
boom is beyond the transport position, the control func-
tions are interlocked to prevent simultaneous operation of
any boom function with drive/steer. The first function set to
be operated while in this mode, becomes the master func-
tion set. In other words, while operating drive/steer func-
tions the boom functions are inoperable. Likewise, while
operating boom functions drive/steer functions are inoper-
able.
NOTE: For more detailed information concerning system
adjustment and operation, refer to Section 6 - JLG
Control System.