| 摘要 |
A ladder has a first frame member and a second frame member. The second frame member folds to a position within the confines of the first frame member to provide a thin, easily stored ladder for use within a household. The step of the is provided with one or more keyhole-shaped openings in which the bottom of the keyhole-shaped opening is open. The first frame member includes at least one cross member for supporting each of the one or more steps of the ladder. The cross members also provide a pivot axis about which the step rotates when folding or unfolding the ladder. The cross member has a circular cross-section at each of the ends where it is attached to the first frame member. Inboard from the circular cross member ends, is a crimped portion or portions. The crimped portion or portions of the cross member are dimensioned so that the crimped portion can pass through the open end of the keyhole openings in the step. The crimped portion or portions are spaced inboard from the ends of the cross member so that once the cross member passes through the keyhole, the step can be positioned over the circular portion of the keyhole shaped opening in the step. Once one end of the stair is attached within the keyhole, the other end of the cross member can be attached in the same way by sliding the stair toward the first frame member so that the crimped portion can be passed through the second keyhole-shaped opening. Since the step has the keyhole shaped opening, the step can be placed on the cross member after the cross member is attached to the frame.
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