Abstract: An impact printer has a print band moving longitudinally around pulleys with one side of the band moving in contact along a rigid platen and the other side having engraved characters presented along a print line of a print medium (e.g. paper and ink ribbon). The leading edge of platen is squared off (e.g. sharp) to scrape contamination off the band. A row of hammers impact the print medium against the band between the hammers and an impact surface of the platen. The impact surface of the platen contains multiple longitudinal grooves which start slightly back from the leading edge of the platen and which prevent increased friction force between the band and platen from occurring as the band wears the platen impact surface smooth.

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 apparatus has a frame member supporting an endless revolving type band in alignment with a row of print hammers with a gap therebetween. Ribbon spools with ribbon wound thereon are rotatably supported in spool housings at either end and on opposite sides of the frame member. The spool housings each have a receptacle portion and a cover portion which enclose the spool. A gap in the spool houses enables the ribbon to extend between the housing and through the gap. The ink ribbon is guided through the gap in parallel with the row of hammers and at an angle to the print line by a set of guide pins on the cover of one spool housing and a set set of guide pins mounted on the frame member in proximity with the other spool housing. Both sets of guide pins engage the same side of the ink ribbon in a manner whereby touching the ribbon is not required to install or remove the ribbon from the printer apparatus.

Abstract: A platen for a line printer has a polymer wear resistant strip on a base support. To reduce frictional drag on the band which is in sliding engagement with the wear strip, the leading edge of the strip is slanted against the direction of motion of the band and is provided with grooves that run perpendicular with the leading edge.

Abstract: A paper gap adjustment mechanism having two coaxially mounted cams which have a camming surface with a linear transition area for forms thickness adjustment and an adjacent ramp area for moving the platen open position plus a straight radius area at the top of the ramp area. A lever is attached to the cams for both controlling forms thickness and platen gap open but the printer operator actuates this lever itself only when controlling the forms thickness positions. A second lever is rotatable on the cam shaft also. The second lever is provided with detent means engageable by the first lever so that rotation of the second lever rotates the first lever and the cams from the set position of the first lever to the open position. The detent means has multiple set positions at which the first lever is engaged when the first lever is rotated to set thicknesses. Rotation of the second lever from the open position to closed position automatically returns the first lever to the prior set position.

Abstract: A pulley for connecting a driven device, that is sensitive to speed variations, to be driven by an a.c. motor that is susceptible to speed variations, caused by power line disturbances. The pulley has a peripheral drive surface for a belt drive and two side surfaces through which an opening is formed to receive a drive shaft that is turned by the a.c. motor. One of the sides of the pulley has a slot formed therein with surfaces on each side of the slot. A resilient material of a preselected Durometer value is positioned within the slot and contiguous with at least one of the surfaces in the slot, against which an element projecting from the drive shaft acts to turn the pulley. During a momentary slowdown in the motor speed, the projecting element moves away from the resilient material and permits the momentum of the driven device to maintain its speed while the motor recovers its speed.