UNDERCARRIAGE MLC300 SERVICE/MAINTENANCE MANUAL
8-4
Published 11-22-17, Control # 257-02
Reverse Travel Operation
See Figure 8-1 and Figure 8-2 for the following information.
To enable the travel control system, the switches listed
below must be in the stated positions:
• Seat safety switch closed
• Travel park switch in the UN-PARK position
When the travel park switch is placed in the UN-PARK
position, the CCMB11 control module energizes the travel
brake release solenoid valve, routing hydraulic fluid to the
travel brakes, releasing the brakes.
When either control handle of joystick J2 is moved to the
rearward position, joystick J2 communicates the travel
command to the CCM-10 control module via CAN Bus A.
The CCM-10 control module then begins to ramp up the
PWM duty cycle to the corresponding pump’s electronic
displacement control (EDC). The PWM signal is in proportion
to the speed commanded by the travel control handle.
Increasing the PWM duty cycle increases the pump
swashplate angle, which increases the hydraulic flow from
the pump.
At the same time, the CCM-10 control module
communicates the reverse travel command to the IOLC33
and CCMC11 control modules via CAN Bus C:
• If the left joystick handle is moved rearward, the IOLC33
control module energizes the left travel control valve,
shifting the valve to the position that allows hydraulic
fluid to flow to the left travel motor for reverse travel.
• If the right joystick handle is moved rearward, the
CCMC11 control module energizes the right travel
control valve, shifting the valve to the position that allows
hydraulic fluid to flow to the right travel motor for reverse
travel.
If high-speed travel mode is selected, the IOSB22 control
module ramps up the PWM duty cycle to the corresponding
travel motor control solenoid to increase the motor speed
until the commanded travel speed is achieved.
The following sensors provide feedback to the control
system:
• Pump 3 pressure transducer
• Pump 4 pressure transducer
• Left travel psi pressure transducer
• Right travel psi pressure transducer
• Left travel motor speed sensor
• Right travel motor speed sensor
The control system uses this feedback to adjust the pump
and motor flows to maintain the speeds commanded by
joystick J2.
No Travel
When joystick J2 handles are in the neutral position, the
travel pumps are de-stroked and the left and right travel
control valves remain in the center position, blocking
hydraulic flow from the pumps to the travel motors. The
travel brake release solenoid is deenergized, allowing spring
force to apply the travel brakes.
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