JLG 1250AJP Operation & Safety Manual page 58

Machine Operation
4.3.4 Automatic Boom Control System
During combined tower lift and main lift functions, the control system will maintain the
tower lift speed and automatically vary the maximum main lift command as needed to
compensate for the movement of the tower.
The interaction of the main boom and the tower boom is slightly different when the
main boom is above or below 60° relative to gravity.
Tower Lift Up/Down - Main Boom Below 60°
During tower lift up or down with the main boom below 60°, the control system will
maintain the angle of the main boom read at the start of the tower lift command or as
read at the conclusion of main lift during combined tower and main lift commands.
Tower Lift Down — Main Boom Above 60°
During tower lift down with the main boom initially above 60°, the control system will
lower the main boom to approximately 60° before starting tower movement. The
control system will then control the main boom to 60° for the remainder of the tower lift
down command.
Tower Lift Up — Main Boom Above 60°
During tower lift up with the main boom already above 60°, the control system will
delay automatic compensation of the main boom angle during tower lift until the main
boom reaches approximately 60°. The control system will then control the main boom
to 60° until the tower boom has reached its maximum height. Continuing to operate the
tower lift up when the tower reaches its maximum height will cause the control system
to automatically raise the main boom to its original angle.
4.3.5 Slow Down System
The control system uses the envelope control sensors to automatically slow down the
tower lift up and tower lift down at the top of the tower path and to automatically slow
down main lift up and main lift down as the minimum and maximum angles of the
working envelope are approached. The control system indicates to the operator this
slow down by flashing the creep light on the platform display. This applies to both
platform and ground controls, however, no indication is made on the ground control
panel.
4.3.6 Controlled Angle
The Controlled Boom Angle System minimizes 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 automatically activates either the tower or
main boom lift up or down during swing and drive commands to maintain a constant
boom angle relative to gravity.
Controlled boom angle is disabled with any envelope violation or failure.
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31222384 1250AJP