| 摘要 |
An agricultural type tractor with lifting devices on the front, rear and both sides for agricultural implements. Each pair of rear drivable wheels which are in tandem pivot about a common axle and each pivotable pair of such wheels is driven by a separate hydraulic motor, with each motor, however, connected to a common control whereby the velocity of the wheels on one side can be increased while the velocity of those on the other is decreased for steering around curves and the like. The arrangement also provides a hydraulically lockable differential to avoid the spinning of one set of the drivable wheels while the other set does not move due to an obstruction or the like. Outboard of each set of drivable wheels is a rotatable supporting element which is mounted from the tractor's frame so as to be displaceable outwardly and upwardly relative to the adjacent 0010 set of drivable wheels. Each supporting element has two wheel members which receive an endless chain tread. One of the wheel members on each side has a displaceable hub portion which is connectable to the adjacent drivable wheel. Such a connection can also be accomplished by displacing the wheel members and arrangements are disclosed whereby through the levers, eccentrics and/or chains the pair of wheel members may be displaced first substantially outwardly relative to the adjacent drivable wheels and then upwardly and vice versa.
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