Abstract: Apparatus for use with a printer which has a pair of tractors that engage sprocket holes in the paper to adjust for different paper widths or to adjust the lateral position of the paper. The apparatus comprises a pair of coaxial lead screws, one attached to a rotatable shaft and the second rotatable on the shaft adjacent to and relative to the one lead screw. One tractor is coupled to each lead screw. Rotation of the one lead screw is obtained by a knob keyed to an end of the rotatable shaft. Rotation of the second lead screw is prevented during rotation of the knob by spring loaded fingers with detent elements engageable with detention gearing on the end of the second lead screw. Rotation of both screws is obtained by rotation and axial movement of the knob on the shaft so that a cam surface on the knob engages cams of the spring fingers to disengage detent elements from the detention gearing and drive gearing on the knob engages drive gearing on the second lead screw.

Abstract: A printer has first and second print mechanisms separated by a gap for the passage of a print medium. The print mechanisms are mounted on relatively movable support members. A gap adjustment mechanisms has one set of cam means for moving the support members relative to each other for both forms loading and forms thickness adjusting. The cam means comprises a pair of elongate cam bars translatable along one support member and follower pins on the other member which are located in camming slots formed in the cam bars. The camming slots have first and second camming sections in the form of linear ramps with gentle and steep slope angles respectively. The cam bars are translatable by pinion gearing in engagement with rack gearing on the cam bars, the pinion gears being on a shaft rotatable by a knob to thereby cause the follower pins to be cammed by either the first linear ramp for forms thickness adjustment or the second linear ramp for forms loading.

Abstract: Apparatus for incremental feeding of a paper web from an arborless supply roll over a transverse dancer bar resiliently supported at each end with the respective supports having different and variable spring rates to effect uneven pulling of the web during feeding and thus jogging of the supply roll. This action maintains a tight wrap of the outer layers of web on the roll and aids in maintaining web alignment during feeding.

Abstract: Printing platen for positioning a recording medium such as paper which includes an evacuated chamber having a slotted face plate for attracting, holding and guiding the paper. Slots are arranged parallel to each other and the direction of paper travel, and the vacuum attraction causes temporary deformation of the paper so that the slots can effect guiding and tension on the paper during advancement. Effective platen length can be varied to accommodate different paper widths.