Abstract: The invention concerns a grate bar for a grate tumbler of a tumbler grate of a trash incineration installation or similar combustion facility with a base rod showing an outer rod surface and an inner rod surface, as well as side surfaces, a head surface and a foot surface, the cross-section form being T-shaped with a cross rod (15). The invention also concerns a grate tumbler for the tumbler grate of a trash incineration installation or the like with a hollow shaft and a cylindrical carrier construction, with grate-bar carriers resting upon the carrier construction and grate bars mounted upon the carriers, while the grate bars are mounted upon the grate bar carriers (8) in such fashion that the slit (25) between adjacent grate bars (11) is no greater than 1 mm in width on the combustion-chamber side.