Metal rungs for ladder - are fitted into square holes in sidepieces of ladder and are expanded to keep them in place

摘要

The rungs of a ladder are designed to have a good grip on the shoes worn by a person climbing the ladder, and they fit firmly into the sidepieces of the ladder. The sidepieces of the ladder (2) consist of metal sections forming a rectangle with the shorter sides rounded, and the rungs (1) penetrate through one of the long sides and butt against the further long side. The rungs (1) have ribs (3) and grooves (4) formed on their outside surface and are tubular to combine strength with lightness. The extremities of the rungs are expanded (11) to fix them firmly in the side pieces. The ladder may be made of light alloy.