| 摘要 |
PROBLEM TO BE SOLVED: To reduce the height of a lower limit to a without affecting a strength. SOLUTION: In a pantograph link 4 arranged to prevent the overlapping of links in the planar direction, links 6 and 9 are pivotally fixed to generate a gap equal to a link width by projecting parts 6a and 9a, and a link 7 is positioned therebetween when a lower limit is reached. The pivotally fixed part of the links 6 and 9 set equal to a half width where lower side is cut off and the lower end of the link 7 is set equal to a half width where an upper side is cut off, and mutual interference is prevented when the lower limit is reached. Similarly, the links 7 and 10 are pivoted by spacers 16 and 17 so as to generate a gap equal to the link width, and when the lower limit is reached, a link 9 having a slightly shorter end part is housed therebetween. Further, the pivoted part between the links 7 and 10 is set equal to a half width where a lower side is cut off, and interference with a reinforcing plate 17 is prevented when the lower limit is reached.
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