| 摘要 |
1. Joint for folding ladders, comprising on one hand 2 side-plates 1 and 2 one of them with several notches and the other with one notch only, placed on a same radius with regard to the said side plate pivoting hollow shaft, each integral with one ladder upright and on another hand a spring activated locking finger 13, with as specification that side plate 1 receiving locking finger 13 first, comprises several notches when the other side plate 2 has only one. |
