Abstract: A sheet stacking offsetting system with a stacking tray offsetting movement system with which printed sheets from a reproduction apparatus are stacked offset relative to one another, with a simple rotary drive of an eccentrically rotated extending pin cam which reciprocally drives a simple two part cam follower providing a variable width cam follower slot positively engaging the eccentrically rotated cam to smoothly reciprocate the sheet stacking tray. The slot width is automatically reduced by spring loading movement of one of the two parts of the cam follower so that both sides of said slot directly engage the eccentrically rotated cam at all times. The cam follower slot is also open ended and beveled to easily assemble the pin cam into that open end.

Abstract: In a sheet ejection and stacking system, such as for a document handler output, in which an upper sheet feeding and ejection unit with a sheet ejection path is repositionable between an open and a closed position relative to a lower sheet stacking unit which is providing a sheet stacking tray for the ejected sheets, here a platen cover unit. The sheet stacking tray has an automatically adjusting sheet stacking registration edge wall defining system which is automatically maintained closely adjacent to the sheet ejection position of the upper unit. This system is defined by upstanding stack retaining wall members movably mounted to the sheet stacking tray and a plurality of aligning post members integral the upper unit which automatically engage and move the stack retaining members into alignment with the upper unit, into a proper sheet receiving position therewith, when the upper unit is closed.