Five-cylinder positioning system, for a multiple cylinder rotary offset printing machine system for applying printing on a substrate (6), selectively, in prime-and-verso printing, in double prime printing or in single prime printing, comprising
- an impression cylinder (1);
- a first (3) and a second (2) blanket cylinder;
- a first (5) and a second (4) printing cylinder, each associated with a respective blanket cylinder;
- a first eccentric bearing (12) supporting said first blanket cylinder (3);
- a second eccentric bearing (8) supporting said second blanket cylinder (2);
- first positioning means (13, 18) coupled to the first eccentric bearing (12) and selectively positioning the first blanket cylinder (3) in any selected one of at least the following three positions:
- (a) a first printing position, in which said first blanket cylinder (3) is engaged against said second blanket cylinder (2) to provide for prime-and-verso printing on the substrate, said substrate being passed between said blanket cylinders (2, 3),
- (b) a second printing position, in which said first blanket cylinder (3) is engaged against the impression cylinder (1) to provide single prime printing, or in combination with the second blanket cylinder (2) for double prime printing on the substrate (6), said substrate being passed between the impression cylinder and the respective first and second blanket cylinders (3, 2);
- and
- (c) a removed position, in which said first blanket cylinder (3) is removed from engagement with both the impression cylinder (1) and the second blanket cylinder (2), to permit exchange of a plate on the associated first plate cylinder (5) while the machine is operating and printing on the substrate (6) by means of the second blanket cylinder (2),
- second positioning means (9, 10) coupled to said second eccentric bearing (8) supporting the second blanket cylinder, separately positioning said second blanket cylinder (2);
- and
- said first positioning means comprising, in accordance with the invention,
- a single positioning element (18) having three positioning control positions corresponding to said first blanket cylinder positions (a), (b) and (c);
- an unlocked, freely rotatable means (15), rotating about an axis of rotation (14);
- means (16) for transferring motion of the single positioning element (18) to said rotatable means (15) to rotate said rotatable means;
- link means (13) transferring rotary movement of the rotatable means to the eccentric bearing (12) to control the position of eccentricity thereof, comprising
- an essentially straight link element (13) having a link axis;
- and
- coupling means (151) for coupling said link element (13) to said rotatable means (15) at a position defining a crank arm, and located such that the link element (13) has a component of motion with respect to the axis of rotation of the rotatable means (15) which, upon rotation of said rotatable means through an angle of about 180.degree. upon transfer of motion thereto by said motion transfer means (16) between a first (a) and a second (b) positioning control position of said single positioning element (18) corresponding to first blanket cylinder positions (a) and (b), places the link axis of said link element (13) at least approximately at an intersecting position with respect to the axis of rotation (14) of said rotatable means (15) when placing said first blanket cylinder (3) at either printing position (a) or (b),
- so that no relative rotary forces will be transferred from the eccentric bearing (12) to said rotatable means (15) and hence to the positioning element (18) due to the "dead center" positions of said link element with respect to said axis of rotation when the blanket cylinder is in either of the printing positions (a) or (b),
- said single positioning element (18) when in a third positioning control position (c) controlling rotation of said rotatable means (15) through an angle of about 90.degree. to place said first blanket cylinder (3) in a position (c).