JLG 1500SJ Service Manual - Manual (Page 247)

SECTION 4 - BOOM & PLATFORM
3121262 – JLG Lift – 4-1
SECTION 4. BOOM & PLATFORM
4.1 BOOM SYSTEMS
NOTE: For more detailed information concerning system
adjustment and operation, refer to Section 6 - JLG
Control System.
Broken Cable Indicator System
The boom on this model is a 4 section proportionally
driven telescopic boom. The inner mid boom is driven
directly by the telescope cylinder. The outer mid and fly
booms are each driven by separate wire rope systems.
Each rope system contains redundant ropes that are
capable of allowing the operator to unknowingly continue
use of the machine with a single rope failure. These kinds
of failures with the extend ropes are self revealing to the
operator so proper action can be taken. Failures within the
fly extend ropes are self revealing as they are exposed on
the exterior of the boom where a broken rope would be
obvious. Failures within the outer mid ropes require the
addition of the Broken Cable Indicator System in order to
be self-revealing to the operator. This system uses a prox-
imity sensor to detect excessive movement of the sensed
rope as would be expected with a rope failure. A broken
rope detection results in illuminating the Cable Break indi-
cator on the platform control panel. No restrictions are
made to the functionality of the control system. It is the
responsibility of the operator to take the appropriate
action.
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. When the footswitch is depressed, the
controls are enabled and the operator has 7 seconds to
operate any control. 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 enabled light will
be illuminated in the platform display panel. When the
time limit has been reached, the enabled 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 releas-
ing all functions, then releasing and re-depressing the
footswitch.
Transport Position Sensing System
The transport position sensing system uses the main
boom angle sensors, the main boom length sensor
mounted in the pivot end of the main base boom in addi-
tion to the boom length switch mounted on the platform
end of the main base boom and length switches mounted
to the jib fly boom to sense when the main boom and jib
boom are in the position associated with high speed
travel. Above transport angle is recognized when one
main boom angle sensor reads more than 6° in relation-
ship to the turntable and resets to within transport position
when both main boom angle sensors read less than 4° in
relationship to the turntable. Transport length is recog-
nized when the main boom length switch and main boom
length sensor read less than 1 ft (0.3 m) extension for the
main boom. In addition the jib boom length switches must
indicate fully retracted and the jib boom must be locked in
line with the main boom. During failures of either the main
boom length switch or the main boom length sensor the
main boom transport length will be determined by the
remaining sensor or switch. In addition for a failure either
jib boom length switch, jib length will be determined by
the remaining switch.
This system is used to control the following systems:
• Beyond Transport - Drive Speed Cutback System
• Drive/Steer - Boom Function Interlock System (CE
Only)
• Jib Stow System
• Axle Extension System
• Oscillating Axle System
Beyond Transport - Drive Speed Cutback
System
When boom is positioned beyond the Transport Position,
the drive motors are automatically restricted to their maxi-
mum displacement position (slow speed).