Abstract: An apparatus and method is disclosed for slidably contacting and pressing upon the back side of a conveyor to urge an advancing corrugated paperboard sheet into substantially uniform contact with adjacent laterally extending heating surfaces irrespective of any thermally induced deflection or bowing thereof. A plurality of heating chests arranged in side-by-side relation define the series of laterally extending heating surfaces. A conveyor belt is positioned opposite the series of heating surfaces for advancing the corrugated paperboard sheet longitudinally along a predetermined path of travel. A plurality of contact assemblies provides the sliding contact with the conveyor belt. Each contact assembly, in turn, preferably includes a plurality of contact shoes arranged in side-by-side relation and carried by a laterally extending supporting frame. The contact shoes have contact surfaces slidably contacting the back side of the conveyor belt.