Abstract: An inking system for a rotary printing press, such as a flexographic printing press, including a pair of axially spaced doctor bars each having a pair of doctor blades to define ink chambers between the doctor bars and an inking roller. An ink separator plate is positioned between and in contact with the innermost ends of the doctor bars and includes a curved concave end face for intimate surface contact with the inking roller, to prevent intermixing of the separate ink colors that are provided to the respective ink chambers. The ink separator plate extends at right angles to the axis of the inking roller, and is pivoted on a pin that has an axis that is parallel to the axis of the inking roller to permit the plate to be urged by gravity into surface contact with the outer periphery of the inking roller.

Abstract: The plate cylinder of a printing press is driven at a non-uniform speed to suit a particular repeat length of the web to be printed. If the repeat length is shorter or longer than the plate cylinder circumference, the plate cylinder is respectively accelerated or retarded from web speed between successive imprints by being connected to the output of differential gearing of which a first input is connected to a drive gear and a second input is connected to a gear oscillated by means of a cam follower of a cam rotating together with said drive gear.