Manitowoc Published 12-05-17, Control # 035-23 1-37
18000 SERIVCE/MAINTENANCE MANUAL INTRODUCTION
As travel control handle nears neutral position, node-1
controller compensates for hydraulic system leakage or
changing engine speed. Node-3 and/or node-5 controller
sends a zero output voltage to pump EDC to move
swashplate to center position. After travel control handle
command is off for a preset time, a zero output voltage is
sent to disable travel brake solenoid valve HS-4. Travel
brake solenoid valve shifts to block pilot pressure to brakes
and opens a line to tank. Brakes apply.
Two-Speed Travel Operation
Travel speed switch allows operator to select low speed
when smoother starts and precise control over the load is
required. Low speed places travel motor in maximum
displacement (high torque, low speed) position and prevents
motor from shifting to high speed.
Place travel speed switch in high speed when maximum
available travel speed is required (normal operation).
Hydraulic pressure required for releasing travel 2-speed
solenoid valve is from high pressure accessory pump system
through a pressure reducing valve at 500 psi (34 bar).
When travel speed switch is in low speed position, node-7
controller sends a 24 volt output to enable 2-speed travel
solenoid valve HS-5, shifting valve and directing hydraulic
pilot pressure to P/C (Pressure/ Compensated) valve. The P/
C valve shifts PCOR (Pressure Compensated Over-Ride)
spool placing travel motor in maximum displacement (high
torque, low speed) position. Travel motors remain in this
position until travel speed switch is placed in high speed
position and engine speed is more than 1500 RPM.
When travel speed switch is in high speed position, travel
motors shift to minimum displacement (low torque, high
speed) automatically if engine speed is above 1500 rpm and
system pressure is below 3,915 psi (270 bar). If engine is
below 1500 rpm, 2-speed travel solenoid valve HS-5 is
enabled although travel speed switch is in the high position.
Travel two-speed solenoid valve HS-5 is disabled, shifting
valve and removing hydraulic pilot pressure to P/C valve,
allowing motor to operate in PCOR mode.
Travel Cruise
Travel cruise switch on right console locks-in any travel
command. This allows crawler track to operate in either
direction at a selected speed without manually moving travel
handles. When moving at desired speed and direction, move
travel switch to cruise position. The travel pump flow
requirements and direction is locked-in. When a travel
handle is moved to neutral position, the travel speed and
direction is maintained.
Moving the travel switch to off position or moving either
travel handle in opposite direction from neutral, opens travel
cruise circuit and returns control of travel system to the
operator.
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