| 摘要 |
The ladder side pieces (1) comprise box beams, and the rungs (2) are attached to them by end tongues (10,11) which are inserted in apertures in the side pieces (1) and bent so that they locate against them. The beams comprise two thin plate bodies (4,5) joined to each other by folding to form flanges. The thin plate body facing the rungs (2) has a greater material thickness than the other. Each side piece has reinforcements (9) in the form of embossments in its outer body (9), and similar reinforcements (12,13) are provided in the inner bodies (7) in the form of longitudinally running ribs. At least one tongue (11) of a rung (2) in the bent position locates against the convex side of a rib (12) in the inner body (7) of a side piece. Each rung has apertures with bent edges. |
