Abstract: A sheet sorting apparatus of the shifting tray type employs a pair of helical coils, each coil being predominantly wound with a number of turns of a first pitch, and containing at least one turn of a second, coarser pitch. The ends of each coil are held by through holes of a center rod that extends along the longitudinal axis of each coil, a coil and center rod thus forming a coil assembly. Each center rod is rotationally supported and has a rotational drive coupling attached at one end; a rotational driver being attached thereto is able to rotate both coil assemblies in the same direction at the same speed. A number of trays are arranged in a vertical stack, each tray capable of supporting a number of sheets and having a tray lift insert attached at each side. The tray lift inserts each have a helical passageway therethrough for accepting at least one revolution of one coil therein.