Abstract: A sheet feed tractor of the type used in printers for automatically advancing paper and the like has a recess in one surface of the chassis about the passage for the support shaft and axially extending, resiliently deflectable fingers in the recess and through which the support shaft will pass. The fingers are disposed in substantially alignment with the drive belt and are deflected inwardly by a rotatable clamping member disposed thereabout to effect clamping action on the support shaft substantially in alignment with the drive belt. This orientation of the clamping action precludes inadvertent movement of the tractor on the support shaft during clamping of the tractor thereon and also eliminates undesirable torque on the tractor when the tractor is operating by essentially eliminating any moment arm between the clamped area and the center line of the drive belt.

Abstract: A tractor for driving web material has an endless belt which travels about spaced apart drive and idler sprockets, one of which is an entrance sprocket and the other an exit sprocket. The idler sprocket is journalled in a support member which is movable on the tractor chassis by an adjusting member to vary the spacing between the sprockets and thereby adjust the tension in the belt. The belt carries the paper over a rectilinear path between the sprockets and the chassis has upper surfaces along that path which rise prior to the exit sprocket to lift the paper on the drive pins on the belt and provide a ramp surface clearance to effect clearance of the drive pins in the perforations of the paper so that they rotate downwardly without excessive wear and friction between the web around the perforations and the surface of the pins.

Abstract: A tractor for a web feeding assembly having spaced support and drive shafts has a chassis providing a pair of apertures extending therethrough and a belt extending thereabout. A drive pulley mounted in one of the chassis apertures is engaged with the driven surface of the belt and has an aperture therethrough receiving the drive shaft, and a cantable insert within a pulley body defines at least a portion of the drive shaft receiving aperture. As a result, irregularities in the drive shaft, and variations in axial spacing of the shafts occurring during operation, may be accommodated by canting movement of the cantable insert within the pulley body. A convexly arcuate belt support surface cooperates with the drive pulley to define the web drive path for the belt therebetween. A resilient spring clamp is mounted adjacent the other aperture in the chassis and releasably clamps the tractor on the support shaft.

Abstract: A tractor for a web feeding assembly has a chassis providing a pair of apertures extending therethrough and a belt extending thereabout. A drive pulley mounted in one of the chassis apertures is engaged with the driven surface of the belt and has an aperture therethrough receiving the drive shaft. The pulley has a pair of elements, one of which has axially extending resiliently deflectable posts thereon and the other of which has means thereon engaging the posts. Resiliently deflectable means on the second pulley element defines at least a portion of the shaft receiving aperture and resiliently bears upon the drive shaft over a portion of its length. The deflectable means provides a passage portion of reduced cross section to engage the surface of the shaft. As a result, irregularities in the drive shaft, and variations in axial spacing of the shafts occuring during operation, may be accommodated by deflection of the deflectable means and of the posts.

Abstract: A tractor for a web feeding assembly has a chassis providing a pair of apertures extending therethrough and a belt extending thereabout. A drive pulley mounted in one of the chassis apertures is engaged with the driven surface of the belt and has an aperture therethrough receiving the drive shaft. Resiliently deflectable means on the pulley defines at least a portion of the shaft receiving aperture and resiliently bears upon the drive shaft over a portion of its length. The deflectable means provides a passage portion of reduced cross section to engage the surface of the shaft. As a result, irregularities in the drive shaft, and variations in axial spacing of the shafts occuring during operation, may be accommodated by deflection of the deflectable means.

Abstract: An integrally formed molded print wheel of the daisy wheel type for mounting on an arbor assembly of a printer includes a generally cylindrical hub and a generally annular support disc at one end of the hub and of larger dimension. A multiplicity of webs connect the hub to the support disc, and a multiplicity of flexible character arms extend radially from the support disc with each arm having an indicium adjacent its outer end for printing. A multiplicity of rib elements are integrally formed in the central passage of the hub and have a tapered portion to detachably secure the print wheel on the arbor of the printer.

Abstract: A sheet-feed tractor is provided with raised land portions adjacent its drive and idler wheels. The raised land portions are positioned on the chassis of the tractor and shaped to form wall surfaces that are in radial registration with borders on a drive belt trained around the drive and idler wheels. The wall surfaces provide a positive means for preventing outward movement of the drive belt off the drive wheel and therefore prevent their disengagement.