Variable format offset printing machine having a central impression cylinder

A variable format offset printing machine having a central impression cylinder, comprising said central impression cylinder on which a web printable substrate is supported and a plurality of printing stations arranged around the central impression cylinder, the central impression cylinder having a web inlet side and a web outlet side, each of said printing stations comprising a blanket cylinder of variable diameter, a plate cylinder of variable diameter, and an offset inking unit, said blanket cylinder, plate cylinder and offset inking unit being movable between respective withdrawn positions and respective multiple working positions for different diameters of the blanket and plate cylinders, wherein:

• the blanket cylinder and the plate cylinder are rotatingly supported on respective first and second supports connected by respective first and second horizontal linear guidance means to a main frame which rotatingly supports the central impression cylinder, said first and second supports being movable in linear horizontal directions between their withdrawn positions and their working positions;
• the offset inking units of all the printing stations which are located at one and the same web inlet or web outlet side of the central impression cylinder are mounted on at least one auxiliary frame in which the offset inking units are superposed on one another and staggered so as to follow the circumference of the central impression cylinder, said auxiliary frame being connected by horizontal linear guidance means to said main frame, the auxiliary frame being movable in a linear horizontal direction between its withdrawn position and its working position;
• and
• the main frame comprises an operator side main frame wall and a gear side main frame wall having respective middle regions on which the central impression cylinder is supported and operator side and gear side upper and lower beams horizontally extending from said middle regions of said operator side and gear side main frame walls and solidly connected thereto.