| 摘要 |
PROBLEM TO BE SOLVED: To provide an expandable ladder body for efficiently performing extension operation or shortening operation, without installing a plurality of strips of operation strings, without arranging a binding part and a pulley of the operation strings in the central vicinity of a horizontal frame of a ladder surface. SOLUTION: This expandable ladder body is composed of a first ladder, a second ladder incorporated into the first ladder and a third ladder incorporated into the second ladder. The expandable ladder body is characterized by being capable of extending or shortening in the longitudinal direction; being capable of moving the operation strings on a rotary surface on one side of a first ladder upper end part from the leg part side in parallel or orthogonal to a ladder surface of the first ladder; being push-fastened in parallel by a spring means; being reversed via the journaled pulley; being hookingly installed by reversing the rotary surface on both sides of a second ladder lower end part via the pulley journaled so as to become parallel to a ladder surface of the second ladder; being installed in an operation string installing part on the other side of a first ladder upper end part; tensioning an extension interlocking string between an extension interlocking string installing part of a first ladder upper part and an extension interlocking string installing part of a third ladder lower part via a pulley of a second ladder upper part; and being capable of performing extension operation or shortening operation by the operation strings. COPYRIGHT: (C)2005,JPO&NCIPI
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