公开(公告)号：WO2008141513A1

公开(公告)日：2008-11-27

申请号：PCT/CN2007/070226

申请日：2007-07-03

Applicant: 王克诚

Inventor： 王克诚

IPC: E06C1/12 ,  E06C1/39 ,  E06C7/08 ,  E06C7/46

CPC classification number: E06C1/32 ,  E06C1/125 ,  E06C1/39 ,  E06C7/42

Abstract: An extension ladder (100) includes a plurality of step sections with one section engaged with the adjacent section longitudinally, each having a pair of tubular uprights (101) on both sides connected by a hollow rung (102). The tubular uprights (101) on both sides become gradually smaller in cross-section from the bottom up so that a nested relationship is formed between adjacent two uprights. Each tubular upright (101) is formed with a pin hole to engage with a locking mechanism (104) disposed in the rung (102). The locking mechanism (104) includes a shifting wheel (109, 111), a transmission unit (110, 112) and two locking pins (105) on both ends with a self-locking unit (106), respectively. When the shifting wheel (109, 111) is shifted to pull the transmission unit (110, 112), the two locking pins (105) can move along the axial direction. The extension ladder can be combined to form a straight combination ladder, a platform ladder or a stepladder.