One of two basic types of systems used to feed sheets of paper into a sheetfed offset printing press (in contrast to a single-sheet feeder). A stream feeder feeds sheets, at a speed slower than that of the press, such that the rear edge of a sheet of paper overlaps the front edge of the successive sheet. The advantages of this type of feeding system include greater sheet control. Since the sheets are moving more slowly than the speed of the press, they do not bounce as much on the feedboard, and it is easier to control their position, preventing misregister and paper jams. When using a stream feeder, a double-sheet detector (a device used to detect when more than the proper number of sheets are being fed) needs to be calibrated to take into account the overlap of sheets. The number of sheets overlapping at anyone time varies by the size of the paper. If a smaller size is being used, there will be at most two sheets overlapping at any one time on the feedboard. If a larger size is being used, three sheets may be overlapping at any one time. (Consequently, a double-sheet detector when used with a stream feeder may more properly be known as an extra-sheet detector.) The basic configuration of a stream feeder is described in Feeding Section: Sheetfed Offset Lithography. (See also Single-Sheet Feeder.)
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