A short, multi-color, web-fed rotary printing press for job printing utilizes a vertical stack of bridge printing units which are supported by horizontally shiftable frame sections. The rubber blanket cylinder of each printing unit is at least twice as large as its associated printing cylinder but is always a whole number multiple in size. The printing cylinder in each printing unit rests on the upper half of its associated rubber blanket cylinder.

A multi-color web-fed rotary printing press is usable for job printing. Several printing devices are arranged as several bridge printing units which are supported by frames, at least one of which is shiftable in a horizontal direction. The bridge printing units are arranged on a lower horizontal plane and a printed web dryer is situated on an upper horizontal plane. The resultant printing press has a reduced overall size.

In a multicolor printing press which has a plurality of printing sections arranged in vertical alignment, the multicolor printing press facilitates adjustment of register position along the feeding direction of a printing medium. The multicolor printing press comprises a plurality of printing sections arranged in vertical alignment, a plurality of the printing sections each including at least one plate cylinder for transferring printing pattern defined on a printing plate carried thereon to a printing medium on which the printing pattern is to be printed, and means, associated with the plate cylinder, for adjusting rotational phase of the plate cylinder relative to the printing medium for adjustment of register position of the printing pattern on the printing medium.

In a multicolor printing press which has a plurality of printing sections arranged in vertical alignment, the multicolor printing press facilitates adjustment of register position between a plurality of printing sections. The multicolor printing press thus has a first printing section which includes at least one first plate cylinder, and at least one second printing section which includes at least one second plate cylinder. The multicolor printing press is also provided with means for rotatably supporting the first plate cylinder in a fixed register position for providing reference position in adjustment of register position in the second printing section, means for rotatably supporting the second plate cylinder, and adjusting means of register position of said second plate cylinder relative to the reference position defined by the first plate cylinder.

In a web offset rotary printing machine having a printing tower with upper and lower portions defining a recess between them, and an interchangeable cassette lodged in the recess and supporting at least plate and blanket cylinders, the upper and lower portions are joined by an elevator mechanism so that the upper portion may be raised and lowered relative to the tower portion to accommodate the interchange of cassettes of different heights. A cassette is supported on transverse linear bearings on the lower portion, and helps support the upper portion when the latter is lowered onto it. The linear bearings allow a cassette to be slid in and out from either side of the machine. The cassettes may be of different heights, thus facilitating optimization of the cylinder arrangement in the cassette. A mechanism is described permitting accurate alignment of form rollers with their associated plate cylinder such that skew adjustments may be made to the plate cylinder when plates or cassettes are changed without upsetting individual form roller adjustments.