INTRODUCTION 16000 SERVICE/MAINTENANCE MANUAL
1-28
Published 05-03-17, Control # 228-03
The travel motors are variable displacement and shift
internally with an adjustable spring in each motor P/C
(Pressure/Compensator) valve, preset at approximately 270
bar (3,916 psi).The travel motors are in the minimum
displacement (low torque, high-speed) position when
starting. When the crawler begins to move, a high system
pressure shifts the PCOR (Pressure Compensated Over-
Ride) spool placing the travel motor in the maximum
displacement (high torque, low speed) position for
breakaway torque.
As the travel control handle is moved to the neutral position,
the Node-1 controller compensates for hydraulic system
leakage or changing engine speed. The Node-3 controller
sends a zero output voltage to the pump EDC to move the
swashplate to the center position. After the travel control
handle command is off for a preset time, the Node-5
controller sends a zero output voltage to disable the travel
brake solenoid HS-5. The travel brake valve shifts to block
pilot pressure to brakes and opens a line to tank. The brakes
apply.
Two-Speed Travel Operation
The travel two-speed switch allows the operator to select
low speed when smoother starts and precise control over
the load is required. The low speed switch places the travel
motor in maximum displacement (high torque, low speed)
position and prevents the motor from shifting to high speed.
When the travel two-speed switch is in the low speed
position, the Node-5 controller sends a 24 volt output to
enable the two-speed travel solenoid HS-6, shifting the valve
and directing hydraulic pilot pressure to the P/C (Pressure/
Compensated) valve. The P/C valve shifts the PCOR
(Pressure Compensated Over-Ride) spool placing the travel
motor into maximum displacement (high torque, low speed)
position. The travel motors remain in this position until the
travel speed switch is placed in the high speed position and
the engine speed is more than 1500 RPM.
Place the travel two-speed switch in high speed when
maximum available travel speed is required (normal
operation). Hydraulic pressure required for releasing travel
two-speed solenoid valve is from the accessory/MAX-ER
pump at 28 to 35 bar (406 to 508 psi). When the travel two-
speed switch is in the high speed position, the travel motors
shift to minimum displacement (low torque, high speed)
automatically if the engine speed is above 1500 RPM and
system pressure is below 270 bar (3,916 psi). If the engine is
below 1500 RPM, the two-speed travel solenoid HS-6 is
enabled although the travel two-speed switch is in the high
position.The travel two-speed solenoid HS-6 is disabled,
shifting the valve and removing the hydraulic pilot pressure
to the P/C valve, allowing the motor to operate in the PCOR
mode.
Travel Cruise
When the travel cruise switch is moved to the cruise
position, an input signal is sent to the Node-1 one controller.
The Node-3 controller sends an output signal to the travel
pumps to lock-in the selected flow requirements and
direction.
Moving the travel cruise switch to the OFF position or moving
either travel handle in opposite direction from neutral sends
an input signal to the Node-1 one controller. The Node-3
controller sends an output signal to the travel pumps to open
the travel cruise circuit and return the control of travel system
to the operator.
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