Abstract: A conveyor apparatus for moving materials unidirectionally has an elongated, upwardly facing trough with at least one longitudinally extending semicylindrical recess in the bottom thereof. A helical flight is positioned in each such recess and is rotated about its longitudinal axis so as to move said materials along said trough. At least one rigid, elongated push-bar is supported in the trough for reciprocal lengthwise movement longitudinally of the trough. Each push-bar has a plurality of longitudinally spaced barbs and/or plows mounted thereon and shaped to advance said materials unidirectionally where the push-bar is reciprocated. Material retaining elements may also be provided on the walls of the trough to oppose movement of the said material in the opposite direction.