Manitowoc Grove RT880E User Manual

Grove Published 11-10-2014, Control # 524-00 8-27
RT880E SERVICE MANUAL UNDERCARRIAGE
8
OUTRIGGERS
Outrigger Circuit
The outrigger circuit consists of four extension cylinders, four
jack cylinders, an integrated outrigger/rear steer valve, front
and rear outrigger control manifolds, pilot operated check
valves and four Outrigger Monitoring System (OMS)
(Optional—Standard in North America) string
potentiometers. 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 in their
respective outrigger boxes; in turn a jack cylinder is mounted
on the end of each outrigger beam. The integrated outrigger/
rear steer valve is mounted on the front face of the carrier
frame front cross member. The front and rear outrigger
control manifolds are mounted on the inside center of their
respective outrigger box. An OMS string potentiometer (if
equipped) is mounted inside each outrigger box. The
potentiometer is connected by a cable to the outrigger beam
to monitor the beam’s position—fully retracted, mid-extend,
or full extended.
The outrigger selector controls are located in the cab on the
front console. Both the integrated outrigger valve and the
manifold solenoid valves are electrically actuated from these
controls. The solenoid switches must be held depressed to
actuate the solenoid valve. The integrated outrigger valve
switch is spring loaded to the off position. The console is
placarded with switch positions.
A sight bubble level is mounted on the left side of the cab by
the door latch plate. The sight bubble level provides the
operator with a visual indication of crane level attitude.
Theory of Operation
The appropriate Extension/Stabilizer Switch must be
depressed before the Outrigger Extend/Retract Switch is
depressed. Depressing one of the outrigger selector
switches causes that solenoid valve to open. As the
Outrigger Switch is moved, the integrated outrigger valve
spool shifts allowing flow to either the extend or retract line
as applicable. If the Outrigger Switch is in the EXTEND
position, the flow continues through the open solenoid valve
to the piston side of the cylinder. If the jack cylinder is to be
extended, the flow first unseats the cylinder check valve then
extends the cylinder. The oil from the rod end flows through
the integrated outrigger valve, and then to the reservoir.
When the Outrigger Switch is in the RETRACT position, the
flow through the selector valve is directed to the rod side of
the cylinder. The oil in the piston side flows through the open
solenoid back to the integrated outrigger valve. If a jack
cylinder is to be retracted, then pilot pressure from the
pressurized retract line unseats the cylinder check valve
allowing oil to flow from the piston side through the open
solenoid valve to the integrated outrigger valve. The
integrated outrigger valve directs the flow to the reservoir.
The integrated outrigger/rear steer valve contains three relief
valves. The main relief is set at 2000 psi (13,789 kPa).
Thermal relief protection is provided on the extend side by a
3000 psi (20,684 kPa) relief valve and the retract side by a
300 psi (2068 kPa) relief valve.

Manitowoc Grove RT880E Specifications

General

Brand	Manitowoc
Model	Grove RT880E
Category	Construction Equipment
Language	English