JLG 1350SJP Service Manual - Manual (Page 237)

SECTION 4 - BOOM & PLATFORM
3121142 – JLG Lift – 4-3
Moment Control System
The Moment Control System is the secondary means of con-
trolling the stability of the machine. This system uses a load
moment pin to attach the lift cylinder of the boom to the turn-
table. This pin is instrumented with gauges allowing the forces
in the pin to be monitored. These forces are used to compare
the actual boom moment (force at a distance) to a predeter-
mined allowable boom moment. In controlling the boom
moment, the position and load of the boom is controlled. The
moment control system will detect moments larger than
expected as well as those smaller than expected. This effec-
tively controls the forward and rearward positions of the
boom. The moment control system varies the maximum
allowable moment based on ground slope. On level ground
and with rated load in the platform, the allowable moments
establish a working envelope slightly larger than the Envelope
Control System’s envelope to minimize interaction of the sys-
tems. With increasing ground slopes and rated load in the
platform, the allowable moments may establish a working
envelope smaller than the Envelope Control System’s enve-
lope and may result in moment violations at the extreme plat-
form positions. Violations of the moment control systems
allowable moment will result in reduced function speeds, BCS
warning light illumination, restriction of functions, and sound-
ing of the platform alarm and the flashing of the BCS light with
attempts to operate restricted functions. The restricted func-
tions due to moment system violations related to forward
reach are disallowing jib functions, lift down, telescope out,
swing, drive, and steer. The restricted functions due to
moment system violations related to backward reach are disal-
lowing jib functions, lift up, telescope in, swing, drive, and
steer. Recognized failures within this system will result in con-
trol by the Envelope Control System, reduced function speeds,
BCS warning light illumination. The boom will be restricted
from leaving the transport position until the failure is resolved.
NOTE: For more detailed information concerning system adjust-
ment and operation, refer to Section 6 - JLG Control Sys-
tem.
Boom Control System (BCS) Functional Check
(Push to Test) System
The machine is equipped with a system for the operator to
daily verify the proper functioning of the Boom Control Sys-
tem (Envelope Control System and the Moment Control Sys-
tem). The operator is instructed to position the boom in the
position described by the instruction decal and to then verify
the control system cut out the telescope movement at the cor-
rect length. When the operator pushes the push button
mounted on the ground control panel, the control system
compares the current moment reading in the moment system
and compares it to the moment expected for this position. If
the current moment is within allowable tolerance for the test
position, the green BCS indicator will illuminate indicating the
system is working properly. If the current moment is not
within the allowable tolerance for the test position, the red
BCS indicator will illuminate indicating the machine requires
service by JLG authorized service personnel before the system
is used. Failure of this test will not restrict the functionality of
the machine and will not cause a system fault. It is the opera-
tors responsibility to take proper action. The machine can be
in either capacity mode of the dual capacity system for this
system check.
NOTE: For more detailed information concerning system adjust-
ment and operation, refer to Section 6 - JLG Control Sys-
tem.
Controlled Arc System
The Controlled Arc System uses the envelope control sensors
to enhance the control of the boom within the working enve-
lope. The purpose of the controlled arc system is to minimize
the interaction of lift functions with envelope edges and to
increase user efficiency. This minimizes the effect of a long
boom working in a comparatively narrow envelope. Because
the boom is permitted to extend to longer lengths at high
angles than at it is low angles, lift commands would normally
cause the boom to violate the permitted envelope while lifting
down or conversely require the operator to frequently com-
mand telescope out while lifting to high heights. The con-
trolled arc system optimizes the envelope shape by
automatically introducing telescope in or out during "lift only"
commands. Telescope flow is regulated during lift commands
to maintain a constant percentage of available boom length
(0% is always fully retracted, 100% is variable as the permitted
length changes when the boom is raised). The target percent-
age will be maintained throughout the lift command whether
it is maintaining 0%, 100%, or any percentage in between. The
target percentage is established at the start of lift command or
end of manual telescope commands when using multiple
functions with lift. The telescope command can be used inde-
pendently or in combination with other functions. Manual
introduction of telescope will override the controlled arc sys-
tem and result in conventional control. Controlled arc will be
disabled with any sensor failure, any moment violation, any
envelope violation, or with auxiliary power functions. The con-
trolled arc functionality and be turned off using the manual