permanent strength of the joint. absence of heavy stress concentration due to absence of bearing between bolts and plates. as bolts are in tension, it does not permit loosening, thus making it most ideal where vibrations are involved. economy: fewer high strength bolts are required than m.s bolts and rivets...
regularly to be sure they are not worn excessively. when these rung mounting rivets become sloppy and loose, we suggest you replace the ladder as these rivets are brass and are meant to provide a hinge/bearing assembly for this folding ladder. these are not field replaceable without special tools, and...