Abstract: Said machines comprise at least a first cylinder (1) for a printing plate, a second transfer cylinder (2) and a third cylinder, printing or counter-cylinder, with both first (1) and second (2) cylinders being hollow, through the interior of which a shaft (5, 6) is inserted belonging to the machine and in that said hollow cylinders (1, 2) of lightweight material, comprise rigid bearing rings (7, 8) located at the ends of the referred cylinders, with the same diameter or somewhat greater than the blanket or printing plate (4, 14), taking said diameter from the cylinder shaft (5, 6).

Abstract: The invention relates to a roller cassette for semi-rotary machines, which can be inserted into offset printing units. The invention comprises at least three rollers, namely: at least one printing plate roller in the form of a first roller, one transfer roller in the form of a second roller and a printing cylinder or counter-cylinder in the form of a third roller. The invention is characterised in that the printing rollers (3) in the cassette are disposed in a semi-rotary configuration, with the second and third rollers being disposed in the same vertical plane or with a slight inclination in relation to said plane and the first roller being disposed in a tangential plane or inclined in relation to the plane of the second and third rollers. In this way, when the cassette is inserted into a printing unit (2) that is designed to receive roller cassettes, said unit can print with the specific printing characteristics of the semi-rotary rollers (3).