Abstract: A printing device for duplex printing of a sheet, comprising a feed path for feeding an unprinted sheet and a return path for returning a sheet printed on one side in an inverted orientation to a part of the feed path which is provided with an aligning station for aligning a supplied unprinted sheet and a returned sheet printed on one side. The aligning station comprises two aligning mechanisms which are disposed in spaced relationship in the feed direction and which each comprise two activatable transport nips which, as considered in a direction transversely of the feed direction, are situated a short distance apart so that a sheet fed between the nips can be aligned against one of each of the two transport nips by lateral transport and turning.

Abstract: A collating apparatus is mounted above a copying machine and includes a housing frame enclosing a conveying mechanism for conveying sheets from the copy-ejection part of the copying machine along a vertical path alongside of which are positioned horizontal trays for receiving the copy sheets as collated. The trays have associated therewith guide elements which are balanced in equilibrium in a first position in which they project into the conveying path to guide sheets into their corresponding trays and which are activated by the receipt of a sheet in the tray to a second position in which they are moved out of the path. The guide elements are locked in this second position by pawl-like locking elements until all locking elements are released by an unlocking means activated by the copy machine start button.