Abstract: A web feed tractor which comprises a frame, a drive gear rotatably mounted in the frame, a cylindrical shaft fastening member mounted on the frame with a portion thereof protruding from the frame, an endless toothed timing belt trained about the frame and drive gear, a cover plate assembly peripherally surrounding the endless belt in peripherally spaced relationship to the belt to define a track of a web to be fed, a web support or guide member positioned adjacent to the endless belt in side by side relationship, a lock ring rotatably mounted on the protruding portion of the shaft fastening member and a switch mechanism positioned in the track of the web so as to be operated by the web as the web passes through the track.

Abstract: A web feed tractor for a printer which comprises a timing belt having outer web engaging pins and inner teeth, a sprocket wheel drivingly connected to the belt and having belt engaging cogs and a guide portion, a frame rotatably receiving the sprocket and having a guide portion, a web holding plate assembly pivoted to the frame, and a web support plate connected to the frame and having a lock and a lock ring fitted on the lock.