| 摘要 |
PROBLEM TO BE SOLVED: To increase a raising and lowering stroke of a leg body, to reduce the sliding resistance of a sliding face to a predetermined height, and to form no step of vertical two steps in the outer peripheral face of the leg member. SOLUTION: The inner leg 7 can be raised and lowered by a raising and lowering mechanism 28, a middle inner leg 6 is always downwardly biased by an downwardly biasing means 24, the middle inner leg 6 is raised against the biasing means 24 in association with the inner leg 7 when the inner leg 7 is raised to a predetermined height. COPYRIGHT: (C)2008,JPO&INPIT
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