| 摘要 |
PROBLEM TO BE SOLVED: To provide a storable ladder which is retrofitted to an existing manhole or the like, facilitates fall prevention and entering/leaving motion of the operator into/from the manhole, and safely achieve fall prevention even immediately after opening of a manhole cover. SOLUTION: In mounting the ladder in the manhole, a ladder frame unit 1 is mounted on one portion of an inner wall in the vicinity of a ground opening of the manhole H, and a catch 2 is mounted on the opposite portion of the inner wall. The ladder frame unit 1 is formed of a fixture 3 fixed to the inner wall and a ladder frame 5 rotatable about a swing shaft 4 of the fixture 3 in a rising/falling manner. When the ladder frame 5 is horizontally laid, the tip of the frame is borne by the catch 2. Further, the ladder frame 5 has a through slot s which allows insertion of the swing shaft 4 therein. Thus, when the ladder frame 5 is set in a vertical position, it can be vertically deviated, and an engaging pin 10 arranged at a base-side end of the ladder frame 5 is fitted into a pin fitting hole 9h formed in an engaging plate 9, to thereby fix the position of the ladder frame 5. COPYRIGHT: (C)2004,JPO
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