Safety ladder with tubular rungs - has ribs on stringers protruding into rungs with bolts to prevent rotation

摘要

The safety ladder has tubular rungs fixed to the stringers so that they cannot rotate. The stringers (1) are fitted with a rib (2), or more than one, on the inside of their walling sections, protruding into the tubular space, or they fit securely on pre-formed or previously work-end ends on the rungs (3). The rungs are fixed by screw bolts (5) or plug pins passing through the profiled walling on the stringer. The ribs may be in pairs, with the ends of the rungs engaging between them. There may be a third intermediate rib, engaging a recess in the end of the rung.