US Patent 7073651 Modular mat gravity-advance roller conveyor

A modular gravity-advance roller conveyor for conveying articles down an inclined path. The conveyor comprises an easy-to-configure modular conveyor mat supported in a conveyor frame with an inclined base. The conveyor mat is constructed of a series of rows of roller-top modules with rollers that extend above the top surface of the mat. Connecting elements along the ends of each row are connected to the connecting elements of adjacent rows to form the mat. The rollers on a roller-top module rotate about an axis of rotation. Modules with rollers that rotate about a given axis of rotation can be combined with modules with rollers that rotate about a different axis of rotation in a variety of patterns to meet common or special conveying requirements.