| 摘要 |
In a pantagraph-type jack, a base comprises an upper base member and a lower base member which are connected to each other relatively movably in the vertical direction, inner ends of a pair of lower arms are swingably connected to the upper base member via a pair of lower pivots arranged in th e horizontal direction, lower sector gears are formed on the outer peripheries of the inner ends of the two lower arms, and a lower rack which meshes with the lower sector gears is disposed in the vertical direction and secured on the lower base member, and it is arranged such that at the same time as the two lower arms are erected the lower sector gears ascend the lower rack. Thus, the amount of lift of the load bearing platform can be increased without increasing the lengths of the lower arms, the upper arms and the threaded rod.
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