Abstract: This invention relates to a printing press including an impression cylinder and a plurality of printing units which include drive gears and plate cylinders which are movable into and out of engagement with the impression cylinder. The press also includes a driven central gear which is coaxial to the impression cylinder and in mesh with all plate cylinder drive gears. The plate cylinders are permitted to have a plate length which is not exactly equal to an integral multiple of the tooth pitch of the plate cylinder gears so that the peripheral length of the plate cylinder is not an integral multiple of the tooth pitch of the central gear. The central gear is operatively connected by a gear train to drive a gear that is secured to the stub shaft of the impression cylinder. The gear train includes a differential gear train which has an input member that is adapted to be driven by an infinitely controllable transmission or by a stepping motor or the like.