| 摘要 |
<p>A tractor unit for wheeled vehicles having fixed draft tongues, the tractor unit including a frame supported at its front end by a pair of laterally spaced steerable drive wheels, and having a supporting leg at its rear end movable between an operative frame supporting position and an inoperative raised position. A support arm extends rearwardly from the frame and is disposed to underlie and support the draft tongue of a vehicle. A locking pin releasably locks the draft tongue to the support arm. The support wheels have generally vertically extending pivot shafts and a generally vertical steering shaft is rotatably carried by the frame intermediate the pivot shafts on a fixed axis. Power transmission mechanism operatively connects the steering shaft with the pivot shafts, and is responsive to rotation of one of the pivot shafts in either direction of steering movement away from a neutral position to rotate the other pivot shaft in the same direction but to a different angular extent.</p> |
