Patent ID: 8205409

Claim:
A grating assembly having longitudinal and axial directions comprising: a plurality of axially spaced longitudinal deep bars each having a top and bottom defining therebetween a first height; a plurality of longitudinally spaced axial crossbars each seated on the deep bars and each having a top and bottom defining therebetween a second height less than the first height; and a plurality of longitudinally spaced metal axial filler bars each having a top and bottom defining therebetween a third height which is less than the second height; wherein the deep bars are part of a first grating subassembly; the crossbars and filler bars are part of a second grating subassembly; the second subassembly has unjoined and joined positions in which it is respectively separate from and joined to the first subassembly; the second subassembly is movable downwardly from the unjoined position to the joined position where it rests on top of the first subassembly; and the tops of the crossbars are substantially flush with the tops of the filler bars in the joined position.