| 摘要 |
Work machines such as road mills having a frame supported by tracked or wheeled ground engaging support units may require the ability to move one or more of the ground engaging units between projecting and retracted positions relative to the frame without reversing the running direction of the repositioned unit. A disclosed work machine has a machine frame supportable by a plurality of ground engaging units. A support device connected between the machine frame and at least one of the ground engaging units has a lifting column adapted to controllably raise and lower the ground engaging unit relative to the frame. A first actuator is connected to the support device to move the one ground engaging unit between the projecting and retracted positions, and a second actuator is connected to the lifting column to maintain the running direction of the associated ground engaging unit in each of the projecting and retracted positions.
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