Abstract: An apparatus for preventing circumferential separation of the meshing teeth (86, 72) of a blanket cylinder gear (84) and a plate cylinder gear (70) includes a first gear (92) having gear teeth (94) in meshing engagement with the gear teeth (86) of the blanket cylinder gear (84). The first gear (92) is rotatable about an axis. A second gear (108) is coaxial with the first gear (92) and is rotatable about the axis relative to the first gear(92). A third gear (136) has gear teeth (134) in meshing engagement with the gear teeth (132) on the second gear (108). A fourth gear (76) is coaxial and rotatable with the plate cylinder gear (72), and has gear teeth (78) in meshing engagement with the gear teeth (134) on the third gear (136). The apparatus further includes spring means (122) for biasing the first and second gears (92, 108) about their common axis in respective directions that are opposite to each other.

Abstract: An improved printing apparatus and method includes plate and blanket cylinders which are rotated at different surface speeds during printing on material. Since the plate and blanket cylinders are rotated at different surface speeds, the area on a blanket cylinder which engages a given portion of the surface on a plate cylinder is changed on each revolution of the blanket cylinder. Therefore, the area of a blanket cylinder which is engaged by the gap in the plate cylinder changes during a printing operation. In addition, the area where an image is applied to the blanket cylinder is moved relative to the surface of the blanket cylinder is tend to minimize build up of ink on the blanket cylinder during printing. The plate and blanket cylinders are driven at different surface speeds by a drive assembly which includes a harmonic drive unit.