Abstract: This invention provides a tray shifting type sorter comprising a number of trays having a couple of trunnions at the rear ends of both lateral sides, respectively and a couple of drive wheel assemblies oppositely installed on both side walls of the sorter. The drive wheel assembly includes a cam wheel shifting the trays and a supplementary wheel supporting the trays over the drive wheel assembly. The invention further provides a sheet jogging device for aligning the copy sheets with an alignment rod using a wire as the power transmission apparatus and equipped with tension change apparatus to loosen the wire, so that the drive apparatus is prevented from being overloaded by the continuous contact between the alignment rod and the copy sheets.