Abstract: An auxiliary drive for the ductor roller of a sheet-fed offset press continues to advance the ductor roller in small angular steps during press stoppages. The damping unit drive which continues to run during press stoppages drives the ductor roller stepwise by way of an eccentric drive linkage and a ratchet wheel disposed on the ductor roller journal. When the press is running, a rocker lever in the drive linkage can be pivoted away from the throw zone of the eccentric for example, by a piston actuated by oil pressure of the press's oil supply system. In alternative embodiments, the lever arm can be pivoted away by a compressed air cylinder or a suction cylinder which become operative when the press is running.

Abstract: A gripper device for manually adjusting the position of a pair of gripper rows disposed on opposite sides of the periphery of double-size sheet-guiding cylinders, to a work and turn angle of exactly 180.degree.. Each of the gripper rows includes a cam follower roller and at least one cam follower roller is adapted to have its center-line displaced relative to the axis of the gripper shaft so that the distance between the axes can be varied.

Abstract: An offset inking unit includes a distributor roll having a first roll train that communicates via a first branch roll with an ink transport roll engaged, as viewed in the direction of rotation of the plate cylinder, by two front inking rolls and having a second roll train connected in parallel to the first roll train that communicates via a second branch roll with a spreader roll which, as viewed in the direction of rotation of the plate cylinder, is engaged at least by the first inking roll of the two front inking rolls. Also as viewed in the direction of rotation of the plate cylinder, the second inking roll of the two front inking rolls communicates at least with another rear inking roll via another ink transport roll. Damping is optionally effected directly on the printing plate or on a front inking roll.

Abstract: A sheet-turning drum in a sheet-fed rotary printing press for optionally first printing or perfecting printing is provided that is simple to assemble and adapted to be changed over for differing printing requirements. To this end, the sheet-turning drum is subdivided into a unitary main member and a cylindrical drum envelope. The latter having a sheet support surface and flanges disposed on its end faces for securing the envelope between mounting flanges on the main member. The sheet support surfaces of the drum envelope can be in the form of a smooth metal surface, an ink-repellent fabric or support rollers retained on carrying rods.

Abstract: A shifting gear for the inkbox roller of a printing press having a freewheeling journal arranged on the roller axis including a drive pin connected to a slide block carried by the journal and a swingably borne slide block frame having a swinging axis connected with an oscillating drive to the press roller, the swinging axis of the slide block frame being shiftably arranged by a setting gear with respect to the drive pin of the freewheeling journal, and the setting gear having a setting sindle and drive nut connected with a bearing lever swingable on the machine frame and carrying the swinging axis of the slide block frame, the spindle having a setting groove whose pitch corresponds to the maximal setting range of the setting gear and the drive nut carrying a guide pin positioned in the setting groove. In the preferred embodiment, the setting spindle is connected with a turning grip and, with interposition of an indexing arrangement, the setting spindle is adjustable in small annular steps.

Abstract: A shift-over device for controlling the turning drum grippers of a rotary sheet printing press optionally changeable for one-side printing or two-side printing and having a relatively rotatable gripper opening cam and an axially movable gripper turning cam includes a rotatable switching shaft carrying a stop arm with adjustable stops mounted on the press frame for engaging the stop arm and limiting the rotation of the switching shaft in opposite directions. A first crank arm is secured to the switching shaft and carries a lash lever coupled to the gripper opening cam for relatively rotating it incident to oscillations of the switching shaft. A second crank arm is secured to the switching shaft and coupled to a push arm having face cams engageable with push rods connected to the gripper turning cam for axially shifting it incident to oscillations of the switching shaft.

Abstract: In accordance with the invention, a plate-clamping mechanism is provided for clamping and locking flexible printing plates on a printing cylinder wherein a clamping jaw fitted into a cylinder cavity has a leading edge for clamping one end of printing plate which is (1) non-parallel to the cylinder's axis of rotation and (2) coincident with the periphery of the cylinder when the clamping jaw is in its opened or closed position. In addition, the clamping jaw's axis of rotation is parallel to the jaw's leading edge. Such a clamping jaw eliminates any void between the printing plate and the cylinder surface which might otherwise exist after the plate is tensioned and clamped: such a void is common in printing cylinders with clamping jaws having leading edges non-parallel to the cylinder's axis of rotation.

Abstract: An arrangement for longitudinally oscillating a doctor blade relative to the form cylinder in a printing press. The arrangement includes a double armed rocker having one arm coupled to the doctor blade and the other arm coupled to a hydraulic cylinder. The rocker is mounted on a central eccentric portion of a pivot shaft through a one way idler bearing and the pivot shaft is rotatably supported in a counteracting one way idler bearing. By oscillating the rocker, through sequential operation of the double acting cylinder, the pivot axis of the rocker is continuously displaced, causing the points of reversal of doctor blade movement to be continuously varied independently of the press operation, while maintaining a uniform stroke. In the illustrated embodiment, a pneumatic control is provided for controlling operation of the hydraulic cylinder, and thus the rocker arm and doctor blade movement.

Abstract: A clamping device for thin flexible printing plates has a tensioning rail at the trailing wall of a wide longitudinal groove in the plate cylinder. The tensioning unit is mounted for axial and peripheral adjustment on a support of "L" cross-section having a first leg seated with respect to the bottom of the groove and a second leg presenting an upstanding reference surface interposed between the tensioning rail and the trailing wall of the groove. A set of tensioning springs recessed in the tensioning rail bear against the reference surface and apply peripheral tension to the plate. A spring detent latches the tensioning rail temporarily against the reference surface, overcoming the tensioning springs while the trailing edge of the plate is being gripped. The spring detent is mounted upon and movable with the support. Screws having a plurality of selectable holes anchor the support in a series of peripheral positions for accommodation of plates of different length.

Abstract: An impression cylinder for a rotogravure press having a recessed sheet stock gripper mechanism with a swivelling mechanism that swivels the grippers within the cylinder contour by revolving the grippers around a theoretical axis on the cylinder contour. The swivelling is rigidly and precisely constrained along an arcuate path by a plurality of arcuate guides disposed along the axial length of the cylinder. The opening and closing of the grippers and the swivelling of the grippers into the cylinder contour are caused to occur in sequence synchronized to the cylinder rotation by cam followers on gripper shaft pivot arms cooperating with cam followers journaled to the gripper shaft that are spring pressed onto cam surfaces fixed to the machine frame at the ends of the cylinder.

Abstract: A fluid supply system for a lithographic printing press in which a fountain roller journalled in the frame of the press and driven at a slow speed is partially submerged so that a film of fluid is formed on its surface. A distributor roller is journalled in the frame parallel to the fountain roller and spaced therefrom to form a gap. A ductor roller movable broadwise in the gap is supported by a pair of arms which are, in turn, rigidly supported by a shaft journalled in the frame. A driving arm having a thrust rod connected thereto is rigidly secured to the shaft. The driving arm is coupled to a cam follower which engages a rotary cam so that upon rotation of the cam the shaft oscillates to swing the ductor roller back and forth for successive engagement of the fountain roller and the distributor roller to convey fluid therebetween. Opposed way surfaces are provided at the ends of the arms oriented generally perpendicular to the plane of the arms.

Abstract: A washing assembly for a lithographic press including a washing roller having a porous resilient surface for carrying a charge of cleaning fluid, the washing roller being mounted in a frame for rocking movement from a disengaged position to a first washing position in which the washing roller is engaged with the surface of the blanket cylinder and a second washing position in which the roller is engaged with the surface of the impression cylinder. A drive wheel is provided at the end of the blanket cylinder for coupling to a driven wheel at the end of the washing roller as the frame is rocked to its first washing position for differential driving of the washing roller to produce relative wiping against the surface of the blanket cylinder. A squeeze roller in pressing engagement with the washing roller prepares the surface of the washing roller to accept a fresh charge of cleaning fluid.

Abstract: A device for the lateral and longitudinal positioning of sheets on the feed table of a printing press, with the leading edge of the sheet engaging a set of front stops and the lateral edge of the sheet in contact with a side guide, enabling accurate registered pick up by a transfer cylinder or the like. Cooperating laterally swingable wiper members are provided both above and below the sheet having friction shoes for wiping the sheet in the direction of the side guide. The friction shoes are connected to the respective wiper members in such a way as to provide freedom of relative movement at right angles to the direction of wipe so that the sheet may move against the front stops at the same time that is being wiped toward the side guide.

Abstract: A sheet-fed printing press installation comprised of a first press unit for printing on one side of a sheet and which is coupled by a chain type conveyor to a second press unit in which there is a transfer drum having a normal set of grippers and an auxiliary set of grippers for (a) additional printing on the same side of the sheet or (b) printing on the opposite side of the sheet. The conveyor has an inlet sprocket for taking of the sheet from the impression cylinder in the first press unit and an outlet sprocket for delivering the sheet to the impression cylinder in the second press unit. First and second transfer drums are interposed in series between the outlet sprocket and the impression cylinder of the second press unit, the first transfer drum having the normal and auxiliary set of grippers. When the auxiliary set of grippers is activated, the sheet is gripped at the trailing edge thereby to reverse the sheet for printing on the second side of the sheet in the second press unit.

Abstract: Sheet coating means for a printing press including a back-up cylinder and form cylinder having an associated fountain, the fountain having a fountain roller rotating adjacent the form cylinder. Also rotating adjacent the form cylinder is a first form roller which is coupled to the fountain roller via a dosing roller. The fountain and its associated rollers are mounted upon a subframe having provision for (a) shifting the fountain roller into liquid transmitting contact with the form cylinder and (b) shifting the first form roller into liquid transmitting contact with the form cylinder thereby, selectively, to change the length of the liquid transference path from the fountain to a sheet carried by the back-up cylinder in accordance with the drying speed of the coating material.