8-25
GRT8100 SERVICE MANUAL UNDERCARRIAGE
Published 3/26/2018, Control # 596-05
OUTRIGGER
Outrigger Circuit
Description
The outrigger circuit consists of four extension cylinders, four
jack cylinders, an extend/retract directional control valve,
front and rear outrigger control manifolds, and an Outrigger
Monitoring System (OMS) (Optional—Standard in North
America). The front two extension cylinders are mounted in
the front outrigger beams and the rear two extension
cylinders are mounted in the rear outrigger beams. The front
and rear outrigger beams are mounted on their respective
outrigger boxes; in turn the jack cylinders are mounted on
the end of each outrigger beam. The extend/retract
directional control valve is part of the carrier combination
manifold valve, which is mounted to the inside carrier frame
rail at the turntable bearing. The front and rear outrigger
control manifolds are mounted on the inside center of their
respective outrigger box. The OMS (if equipped) consists of
a string potentiometer sensor mounted inside each outrigger
box. The sensor is connected by a cable to the outrigger
beam to monitor its position—full, half or retracted.
Both the extend/retract directional control valve and the
manifold solenoid valves are electrically actuated through
operator inputs made at the rated capacity limiter (RCL)
display and controls in the operator cab.
A sight bubble level is mounted inside the cab on the right
side by the emergency stop switch. The sight bubble level
provides the operator with a visual indication of crane level
attitude.
Theory Of Operation
The rated capacity limiter (RCL) system, through inputs from
the operator, controls the extend/retract directional control
valve and the beam and jack cylinder valves on the two
outrigger control manifolds. Actuating an outrigger function
through the RCL causes that respective outrigger jack or
beam solenoid valve to open and the extend/retract control
valve spool to shift to allow flow to either the extend or retract
line as applicable. When extending a jack or beam, the flow
continues through the open solenoid valve to the piston side
of the cylinder. If the jack cylinder is to be extended oil from
the rod end flows through the extend/retract valve, and then
to the reservoir.
When retracting a jack or beam, the flow through the extend/
retract control valve is directed to the rod side of the cylinder.
The oil in the piston side flows through the respective open
solenoid valve, back to the extend/retract control valve, then
to the reservoir. When extending a jack or beam, the flow
through the extend/retract control valve is directed to the
respective open solenoid valve and on to the piston side of
the cylinder. The oil in the rod side flows through back to the
extend/retract control valve, then to the reservoir.
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