Pin-feed assembly

Abstract

A pin-feed tractor assembly for advancing a web of indeterminate length through a printing station and including a timing belt having spaced teeth defining interspersed grooves. The drive sprocket is arranged to engage the notches for moving the belt. Sections of the belt between adjacent notches are rigid while the region of the notches is flexible to permit bending of the belt only at the notches, thereby providing equal stresses in the belt. The outer surface of the belt is provided with feed pins arranged at equi-spaced intervals. The pitch of the belt teeth is one-half the pitch of the perforations in the elongated web which receive the feed pins. The pitch circle of the equi-spaced feed pins is smaller than the pitch circle over the rigid flat portions causing the feed pin to retract somewhat from the web before starting its circular path around the drive sprocket to prevent the web from being damaged or torn. The belt is a molded one-piece member. The design of the tractor assembly is such as to minimize the total number of parts thereby significantly increasing the simplicity of design. In an alternative embodiment, a mechanical contact pair is incorporated to provide paper out and/or paper counting functions. As still another preferred embodiment, optical scanning means arranged within a snap fitting body may be mounted to a tractor assembly to likewise provide paper out and/or line counting functions.

Dependencies are inferred from the claim text.