| 摘要 |
PURPOSE:To aim at ease of adjustment and strength improvement, by attaching wheels to each outer end of a pair of parallel link mechanisms pivotally supported on a vertical shaft and extendedly installed in a car width direction, while constituting these link mechanisms so as to rotate around the vertical shaft, in case of a track-control device for a tractor or the like. CONSTITUTION:When a hydraulic cylinder 29 is extended or contracted and a piston rod 31 is retractably moved in or out, a support arm 20 slidingly moves in a longitudinal direction inside a long hole 32 of a rocking frame 12. And, the arm 20 swivels centering on a vertical shaft 19. With this rotation, the arm 20 and a tie rod 25 form parallel link mechanisms 28 so that front wheels 5 parallelly move while a wheel track increases or decreases. With this constitution, such a smooth motion as being high in strength takes place, thus adjustment comes easy.
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