Definitions for "Bosses"
Keywords:  hubless, ledges, flange, knobs, evenly
raised knobs
Raised ledges or platforms on a backing plate, which evenly support the web of brake shoes. Floating Drum - A hubless brake drum that mounts on an axle flange.
In Medieval architecture a keystone (ornamental, carved and often painted and gilded) at the intersection of ribs in a vaulted roof. Carved, wooden bosses were also used at the rectangular intersection of beams in open wooden ceilings.