HYDRAULIC SYSTEM RT880E SERVICE MANUAL
2-64 Published 11-10-2014, Control # 524-00
AXLE LOCKOUT, REAR STEER AND OIL
COOLER FAN MOTOR CONTROL
MANIFOLD
Description
The manifold cartridge components controls the axle lockout
and supplies flow for the oil cooler fan motor. It is located on
the inside of the left hand carrier frame rail, forward of the
hydraulic swivel.
The pump “P” and tank “T” ports are connected by hoses in
parallel to the outrigger control manifold. The load sense/
CPU control line from the superstructure passes through the
manifold and is connected onward to the pump by two load
sense shuttle valves. One shuttle valve senses oil cooler
pressure and the other senses rear steer and outrigger
pressure. A two position three-way solenoid valve connects
the fan drive to the pump load sense.
The oil cooler motor is controlled by two position three-way
solenoid cartridge valves and is limited to 3.5 gpm (13.3 lpm)
by a pressure compensated flow control valve located
between the two position three-way solenoid and the port to
the cooler motor (see Figure 2-35).
The rear axle lockout hydraulic circuit consists of a pressure
reducing valve, set to 500 psi (3447 kPa), that supplies oil to
two normally closed, two position, two-way cartridge
solenoid valves. The two solenoid valves keep the lockout
cylinders from oscillating unless the turntable is centered
forward. Included in the rear axle lockout system is an angle
encoder located in the top of the electrical slip ring assembly.
The encoder sends a message to the RCL, which converts
the message to a positional angle of the superstructure
relative to the carrier (slew angle). If the slew angle is within
±2° of directly over the front, the RCL sends a CAN bus
message to the Crane Control System to allow axle
oscillation. Upon receiving this message, the Crane Control
System will switch on a digital output, thus energizing and
opening the rear axle lockout solenoids. This allows
hydraulic oil in and out of the cylinders allowing them to
oscillate. If the slew angle is greater that 2° left or right of
directly over front, the Crane Control system switches off the
digital output, thus de-energizing and closing the rear axle
lockout solenoids. This isolates the lockout cylinders from oil
supply and prevents the lockout cylinders from oscillating
because oil is trapped in the cylinders.
The rear steer is controlled by a three position four-way
solenoid actuated directional control valve. The valve shifts
in one direction for right turn and the other direction for left
turn. To ensure the steering cylinders do not drift out of a
locked position, a double pilot operated check valve is
installed between the directional valve and the cylinder work
ports.
Maintenance
Removal
1. Tag and disconnect the electrical connectors to the
valve.
2. Tag and disconnect the hydraulic hoses from the valve.
Cap or plug the lines and ports.
3. Remove the capscrews and washers securing the valve
to the frame bracket. Remove the valve.
Installation
1. Secure the valve to the frame bracket with the washers
and capscrews. Torque capscrews; refer to Fasteners
and Torque Values, page 1-15 for proper torque value.
2. Connect the hydraulic hoses to the ports on the valve as
tagged during removal.
3. Connect the electrical connectors to the valve as tagged
during removal.
4. Verify operation as follows:
• Operate the rear steer left and right to verify smooth
operation.
• On outriggers, swing over the front outriggers to ensure
the oscillation cylinders lockout.
• Remove the electrical connection from the oil cooler
motor two position three-way solenoid valve to verify
that it operation.
5. Check valve and hoses for leaks. Make repairs as
needed.
To Next Page
Loading...
Need help?
General
