| 摘要 |
An aluminium ladder has a C section stringer (1) incorporating an inwardly projecting U-shaped channel (6) on the middle part of the C-shape with a flay base (7) which serves as a bearing surface for the end of the rung (4). The rungs are fixed to the stringer by screws (8) engaging part-circular channels through the inside of the hollow rung. The height of the rung is equivalent to the gap between the two tips (3) of the C-shape of the stringer. The U-shaped channel (6) has grooves down its sides, into which an elastic strip (12) is inserted, covering the heads of the screws, and the interior of the channel itself. |
