Method for on the run plate changes in offset web-fed press

摘要

A printing unit in a lithographic web fed rotary printing press has a plate cylinder and an associated blanket cylinder mechanically coupled via a gear train. A first drive motor drives both the plate cylinder and blanket cylinder. An impression cylinder is associated with the blanket cylinder, the impression cylinder being in rolling contact with the blanket cylinder and being driven by a second drive motor. The web passes through a nip formed between the impression cylinder and the blanket cylinder for printing. A clutch is provided for interrupting a drive connection between the first drive motor and the blanket cylinder, as is a throw-off mechanism for separating the plate cylinder from the blanket cylinder. With the printing unit, the blanket cylinder can remain in rolling contact with the impression cylinder and be friction-driven by the web after the drive connection has been interrupted.