Paper tractor

Abstract

A paper tractor for feeding paper of different widths in printers and the like comprises a rotationally driven shaft having mounted thereon a sprocket wheel which engages in perforations in a length of paper to effect lengthwise feeding of the paper in response to rotation of the sprocket wheel. The sprocket wheel is mounted on the drive shaft to undergo rotational movement therewith and is mounted on the drive shaft to undergo axial sliding movement therealong to enable axial positioning of the sprocket wheel to accommodate paper of different widths. The drive shaft has a polygonal cross-section, and the sprocket wheel has a center tubular sleeve formed of plastic and configured to be slideably inserted over the drive shaft so that rotational movement of the drive shaft is transmitted to the sprocket wheel. The tubular sleeve is provided with a set of axially extending grooves which render the sleeve radially resilient so that the sleeve frictionally engages with the drive shaft with a frictional force-fit which is effective to maintain the sprocket wheel in a preselected axial position during rotational movement thereof yet which permits the sprocket wheel to be manually slid along the drive shaft so as to easily adjust the axial position of the sprocket wheel to thereby enable the feeding of paper of different widths.