| 摘要 |
<p>The hollow tubular section rungs (1) have flat antiskid treads (2) and are bedded in the hollow stiles (3) through corresponding perforations (4). Rung embedment uses rivet sleeves (6) that expand the tubular ends when inserted through circular openings (5) in the stiles at the opposite side to the perforations. The rungs are orientated so that the plane of their treads is horizontal when the ladder is in the work position, occupying a normal inclination.</p> |
