Travel System Operation

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Travel System Operation

When the operator selects the low speed mode, the Machine ECMwill not energize the two speed travel solenoid valve. The displacement change valve does not shift.

Some of the supply oil to the motors is sent by the displacement change valve to the actuator piston on the left and drains the passage to the actuator on the right.

The motor swashplate is moved to the maximum angle.

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Two swashplate actuator pistons control the angle of the motor swashplate. The pistons are controlled by the displacement change valve.

The angle of the swashplate will limit the maximum speed. Since the displacement change valve has not shifted, the swashplate is in the low speed range.

For the motor to turn, the parking brake must be released. To release the brake some of the supply oil is used to shift the parking brake piston against the parking brake spring.

The travel valves direct oil to and from the motors.

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If the displacement change valve does not shift, supply oil to the motor is directed to the actuator piston on the right to hold the motor swashplate at maximum angle.

At maximum angle, the motors will displace more flow and turn at a slower speed and provide more torque.

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When the operator selects high speed in the cab the Machine ECMwill energize the two speed transmission solenoid valve in the pilot manifold.

The two speed transmission solenoid valve directs the pilot pressure to shift the displacement change valve to the left.

The displacement change valve directs some of the supply oil to the minimum angle actuator piston on the right and drains the oil to the actuator on the left.

The motor swashplate angle is reduced.

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When the displacement change valve shifts due to the two speed travel solenoid being energized, the displacement change valve sends some of the supply oil to the lower actuator piston to decrease the swashplate angle.

With a decreased swashplate angle, the motor pistons displace less flow as the piston and barrel assembly rotate. The motor now turns faster, with less torque than at low speed.

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When the two speed travel solenoid valve is energized, pilot oil is directed to the displacement change valve.

The displacement change valve shifts and directs some of the supply oil to the actuator piston on the left to decrease the swashplate angle.