Manitowoc Grove RT770E, Service Maintenance Manual

Page: 286 / 357

UNDERCARRIAGE RT770E
8-10 Published 11/26/2014, Control # 447-05
Hydraulic Pumps
Description
NOTE: Pump output figures are theoretical.
Front Steer
The hydraulic pump is mounted on and driven by the engine.
Pump number 2 provides the hydraulic flow necessary to
power the front steer cylinders and the swing drive system.
The pump is a gear type pump that provides an output of
approximately 122.6 L/min (32.4 gpm).
Rear Steer
The hydraulic pump is mounted on and driven by the torque
converter. Section 2 of pump number 1 provides the
hydraulic flow necessary to power the rear steer cylinders,
the outrigger circuit, and the rear axle oscillation lockout
system. The pump is a gear type pump that provides a flow
of approximately 86.6 L/min (22.9 gpm).
NOTE: For more detailed information, refer to Hydraulic
Pumps , page 2-17.
Front Steering Control Valve
Description
The steering control valve is located under the dash and is
actuated by a conventional steering wheel and steering
column, providing precise, full hydraulic steering. Precise
steering is accomplished by a metering system within the
valve that is directly connected to the steering column and
wheel.
Maintenance
Removal
1. Thoroughly clean the steering control valve and the
surrounding area before removing the hydraulic hoses
from the valve.
2. Tag and disconnect the five hydraulic hoses from the
steering control valve. Cap or plug each hose and the
five ports of the valve.
3. Remove the capscrews, lockwashers, and flatwashers
securing the valve to the bracket and the steering
column. Remove the control valve, leaving the steering
column in the cab.
Installation
1. Position the control valve to the bracket and steering
column and install the flatwashers, lockwashers, and
capscrews. Torque capscrews; refer to
Fasteners and
Torque Values , page 1-16 for proper torque.
2. Connect the hydraulic hoses to the control valve as
tagged during removal.
3. Start the engine and check for proper operation and any
leakage.
Integrated Outrigger/Rear Steer Control
Valve
Description
The outrigger/rear steer valve controls the outrigger circuit
and the rear steer circuit. The valve is mounted on the front
face of the carrier frame front cross member forward of the
swivel.
The inlet section contains a 17,200 kPa (2500 psi) relief
valve and a solenoid valve. The solenoid valve is normally
open bypassing oil from the inlet port to the tank port.
Activation of either the outriggers or the rear steer energizes
the solenoid valve to close and allow oil to flow to the
selected circuit.
The rear steer section contains a three position four-way
solenoid controlled directional valve.
The outrigger section contains a three position four-way
solenoid controlled directional valve.
Both four-way solenoid valves contain manual override
actuators which allow the valves to be shifted if electrical
power is lost.
Maintenance
NOTE: Refer to Hydraulic System , page 2-1 for removal
and installation of the valve.
Functional Check
1. Cycle each outrigger cylinder several times. Verify each
cylinder extends and retracts properly.
2. Rear steer the crane to the left and to the right several
times. Verify the crane steers properly in both directions.
3. Check the valve and lines for leakage. Make repairs as
needed.
Steer Cylinders
Description
The steer cylinders are mounted on the axles, two cylinders
on each axle. The barrel end of each cylinder is attached to a
bracket on the axle housing and the rod end is attached to
the steering lug on the axle end. The cylinders are controlled
hydraulically by the steering control valve.
Maintenance
NOTE: For Disassembly and Assembly procedures, refer
to
Steer Cylinder , page 2-72.