JLG 1850SJ Service Manual - Manual (Page 89)

SECTION 4 - BOOM & PLATFORM
3121619 – JLG Lift – 4-3
Controlled Boom Angle System
The Controlled Boom Angle System uses the envelope control
sensors to enhance the control of the boom by minimizing the
interaction of swing and drive functions with the envelope
edges. This interaction is due to two factors. First, the envelope
is controlled relative to gravity regardless of ground slope and
second, the turntable/boom mounting is effected by swing
and drive functions when the ground slope varies. This can
cause the boom position to vary within the envelope or even
violate the envelope edges when swinging or driving without
intentionally moving the boom. The controlled boom angle
system minimizes this effect by automatically introducing lift
up or down during swing and drive commands to maintain a
constant boom angle relative to gravity for all boom angles
greater than 8 degrees. Controlled boom angle is disabled
with any envelope or moment violations or failures. The con-
trolled boom angle functionality can be turned off using the
manual position of the boom control select switch.
Envelope Tracking
The Envelope Tracking System uses the envelope control sen-
sors to enhance the control of the boom within the working
envelope. Due to the shape of the working envelope, the max-
imum boom angle varies with telescope length. To maintain
unrestricted operation of the boom, the lift down function is
automatically introduced while telescoping in only when the
boom is on the rearward edge of the envelope. This only
occurs when telescoping in along the rearward edge and is
not used elsewhere within the envelope or when telescoping
out. Envelope tracking is disabled with any envelope or
moment violations or failures. The envelope tracking function-
ality can be turned off using the manual position of the boom
control select switch.
Slow Down System
When the main boom approaches the edges of the working
envelope, all functions (except jib and platform functions, tele-
scope in or out on the rearward edge and telescope in on the
forward edge) are automatically slowed down by the control
system to reduce the machine dynamics and improve opera-
tor control. The slow down starts within 4 feet of all edges and
is at the fully reduced speeds 2 feet from all edges. The control
system indicates to the operator this automatic introduction
of slow down by flashing the creep light on the platform dis-
play panel. This feature applies to both platform and ground
controls, however, no indication is made on the ground con-
trol panel. This is not adjustable using the analyzer.
Dual Capacity System
The Dual Capacity System on this machine is a multiple enve-
lope control system as opposed to an indication system. The
control system changes the working envelope and moment
limits to match the capacity select mode to either the 500#
mode or the 1000# mode. It then displays the capacity mode
on the platform and ground display panel and controls the
positions of the boom within the allowable envelope for that
mode. This mode is selectable by the operator with the dual
capacity select switch on the platform control panel. The 500#
mode has the largest envelope. The 1000# mode has a smaller
envelope and requires the jib to be retracted fully. To select
the 1000# mode the boom must already be in the smaller
1000# envelope. When the operator selects the 1000# mode
and this condition is met, the capacity light changes from 500#
to 1000# and the envelope and permitted moment values are
changed accordingly. When the operator selects the 1000#
mode and this condition is not met, both capacity lights will
flash, the platform alarm will sound, and all functions will be
disabled until the capacity select switch is put back into the
500# position.
Swing Speed Proportioning
Swing Speed Proportioning uses the boom length and angle
sensors to improve the comfort, speed and control of the turn-
table swing function. Turntable swing speed is increased as
the distance of the platform to the center of rotation is
decreased. This results in approximately constant platform
speeds regardless of boom position. Swing speed proportion-
ing is disabled with any envelope sensors failure. Disabling of
swing speed proportioning will default to the slowest swing
speed setting.
Platform Load Sensing System
The Platform Load Sensing System consists of 4 load cells,
mounted between the platform and platform support, and a
dedicated electronic interface module (LSS) located below the
platform console. This system compares the capacity mode
(500# or 1000#) recognized by the dual capacity system to the
measured weight in the platform. When the capacity is
exceeded, or when there is a fault in the system, the platform
overload indicator will flash, the platform alarm will sound and
all platform controls (except auxiliary power) will be disabled.
The ground controls are unaffected.
Electronic Platform Leveling
The electronic platform leveling system uses two tilt sensors
(mounted on either side of the platform rotator), a control
valve (mounted to the platform support), a level cylinder, and
the platform control module (mounted in the platform control
box) to automatically measure and control the incline of the
platform with respect to gravity. While in the automatic posi-
tion of the boom control select platform leveling is active
while operating drive, telescope, main lift, jib lift or swing and
is not active while operating any other function (e.g. rotate, jib,
or steer). While in the manual position of the boom control
select platform leveling is active while operating main lift and
jib lift only. The system controls the platform angle relative to
gravity using a set point established during power-up (cycling
of the EMS) or at the conclusion of a manual platform level
override by the operator using the platform level override
switch from either the platform or the ground control. In other
words the operator can choose a platform incline other than
level with gravity and the system will maintain that incline