Abstract: A self-centering pressure roller for a high speed paper feed mechanism. The assembly includes two rollers each having an undercut central portion disposed for rotation on parallel axles. The roller axles are supported on a bracket movable in four degrees of freedom. The rollers are urged toward a platen to provide pressure on a paper sheet or web disposed between the rollers and the platen. The geometry of the roller assembly and the platen is chosen so that the reaction force caused by roller contact with the paper sheet or web causes the downstream pressure roller to exert more force on the sheet or web than the other roller thereby preventing bunching of paper between the rollers. The pressure roller assembly is self-aligning thereby preventing skew of paper fed through the assembly in either direction. The assembly can be easily manufactured without special alignment and is adaptable to accommodate many different paper widths.

Abstract: A printer includes a print wheel having an outer circular row of typefaces comprising digits and punctuation signs and an inner circular row of typefaces comprising symbols, and hammer apparatus for actuating the typefaces of the print wheel to effect printing. The type wheel and the hammer apparatus are mounted on a carriage which travels along a path defining a left-hand group of printing positions and a right-hand group of printing positions. A cam extending along the path of the carriage functions to pivot the type wheel between a position wherein the outer row of typefaces is aligned with the hammer apparatus when the carriage is aligned with the left-hand group of printing positions and a position wherein the inner row of typefaces is aligned with the hammer apparatus when the carriage is aligned with the right-hand group of printing positions.