Grove Published 11-10-2014, Control # 524-00 2-35
RT880E SERVICE MANUAL HYDRAULIC SYSTEM
DIRECTIONAL CONTROL VALVES
Description
The directional control valves direct and control hydraulic oil
flow from the pumps to the boom lift and telescope cylinders,
each hoist motor, the swing motor, the counterweight
removal/cab tilt cylinders, and the front steer cylinders from
the steer control valve. The swing, front steer and accessory
directional control valve/manifold (see Figure 2-21) and the
boom lift/telescope/hoist directional control valve (see
Figure 2-19) are located on the outside of the right
superstructure side plate. The counterweight removal (see
Figure 2-18) and the cab tilt directional control valve (see
Figure 2-20) are located between the left and right
superstructure side plates under the main hoist. Each valve
bank is removed and installed as an assembly.
The boom lift/telescope/hoist is a four section, hydraulic
remote pilot actuated with three position four way spools that
are pressure and flow compensated. It receives pump flow
from hydraulic swivel port 6 and Pump No. 1. The inlet
section of the boom lift/telescope/hoist directional control
valve contains a 0.052 Ø orifice controlling the piston pump
No. 1 differential or standby pressure at 350 psi (2413 kPa)
and a 4350 psi (29992 kPa) clipper relief valve that protects
the piston pump (No. 1 pump) from transient pressure
spikes. The control valve has integral port reliefs that
thermally protect the extend and retract sides of the
telescope cylinders. The boom lift section has an integral
port relief that thermally protects the retract side of the
cylinder. All working sections have a two position three-way
solenoid RCL lockout valve in their pilot end cap except the
boom lift up and telescope in. When the hoist(s), boom lift or
telescope spool is actuated, the signal line (load sense)
connecting the load to the pump is blocked by the shifting
spool causing the pump to go to its full compensating setting.
The individual working sections meter only the required flow
of oil to the function at full pump compensator setting.
The swing directional control valve is a single cast iron
section bolted onto the front steer and accessory manifold.
Refer to Front Steer, Swing and Accessory Manifold. It is
located on the outside of the right turntable side plate. The
valve contains a three position four way open center design
that is remote pilot operated. Both working ports have port
relief valves and anti-void check valves that are flooded by a
150 psi (1034.2 kPa/10.3 bar) resistance check valve located
in the front steer and accessory manifold providing make-up
oil to the swing motor for motor over-run when the valve is
centered. It receives oil from the fixed displacement gear
pump No. 2 internally through the front steer and accessory
manifold and also returns oil internally through the front steer
and accessory manifold.
The counterweight removal directional control valve is a
three section, manually actuated three position four way,
pressure compensated, closed center directional valve. It is
plumbed in parallel with the boom lift/telescope/hoist
directional control valve and the cab tilt directional control
valve. The first and second sections control the left and right
removal cylinders, while the third section controls the
counterweight pin cylinder. The removal cylinder sections
have an integral port relief for both raise and lower functions.
The cab tilt directional control valve is a solenoid controlled
three position four way, pressure compensated, closed
center directional valve. It is plumbed in parallel with the
boom lift/telescope/hoist directional control valve and the
counterweight removal directional control valve.
Maintenance
Boom Lift/Telescope/Hoist Valve Bank Removal
1. Tag and disconnect all of the electrical connectors or
manual control levers.
2. Tag and disconnect the hydraulic lines from the valves.
Cap or plug the lines and ports.
NOTE: The lift/telescope/hoist valve bank weighs
approximately 181.6 lb (82.41 kg).
3. Remove the capscrews and washers securing the valve
bank and remove the valve bank.
Boom Lift/Telescope/Hoist Valve Bank Installation
1. Place the valve bank on the superstructure side plate
and secure it with the capscrews and washers. Torque
capscrews; refer to Fasteners and Torque Values, page
1-15 for the proper torque value.
2. Connect the hydraulic lines to the valves as tagged
during removal.
3. Connect the electrical connectors and manual control
levers as tagged during removal.
Counterweight Removal Valve Bank Removal
1. Tag and disconnect all of the electrical connectors or
manual control levers.
2. Tag and disconnect the hydraulic lines from the valves.
Cap or plug the lines and ports.
NOTE: The counterweight removal valve bank weighs
approximately 43.9 lb (16.4 kg).
3. Remove the capscrews, lockwashers, flatwashers, and
hex nuts securing the valve bank and remove the valve
bank.
Counterweight Removal Valve Bank Installation
1. Place the valve bank on the superstructure side plate
and secure it with the capscrews, lockwashers,
flatwashers, and nuts. Torque capscrews; refer to
Fasteners and Torque Values, page 1-15 for proper
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