| 摘要 |
PROBLEM TO BE SOLVED: To provide a ladder capable of being manufactured easily at an execution site and allowing a worker to ascend or descend it safely. SOLUTION: Single pipes 1, 1, 1 are used as supports, and cross beam members 2 concurrently serving as tread sash bars and protective frames are fixed to the single pipes 1, 1, 1 by clamps 3, 3, 3 at prescribed intervals to form a cage-shaped ladder L.
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