| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a ladder erectable by one operation only and by one hand to set the ladder from the state of a fall prevention frame in a ladder for moving in the vertical directions. Ž<P>SOLUTION: In this fall prevention ladder for an underground structure used commonly as a ladder for moving in the vertical directions, a pair of left and right engagement cam sections 22 projecting inward are installed near a bearing section which pivotally supports a ladder body with a pair of left and right brackets 16 interposed therebetween. A pair of lock sections 25 engaging with the engagement cam sections are installed on the side of the ladder body. Any one of the lock sections and the engagement cam sections can be moved from the origin and returned to the origin, when they are brought into contact with each other in the process in which the ladder body is rotated from the fallen state to the erected state, and biased by an elastic member 30. The lock sections 25 pass through the engagement cam sections and are engaged with the rear surfaces thereof, and in the engaged state, simultaneously make the pair of left and right members on the movable side move so that the lock sections can pass through the engagement cam sections. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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