Patent Publication Number: US-2012031288-A1

Title: Printing unit of a printing press having at least one printing unit

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is the U.S. national phase, under 35 U.S.C. 371, of PCT/EP2010/053009, filed Mar. 10, 2010; published as WO2010/103027 A1 on Sep. 16, 2010; and claiming priority to DE 10 2009 001 475.6, filed Mar. 11, 2009, the disclosures of which are expressly incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The invention relates to a printing unit of a printing press having at least one printing couple. The printing unit has at least one forme cylinder and one transfer cylinder that interacts with the at least one forme cylinder. The printing unit also has an inking unit with a plurality of distribution cylinders. The forme cylinder and/or the transfer cylinder and all of the distribution cylinders of the printing couple are rotationally driven by the same drive motor. The distribution cylinders are driven by the drive motor by a transmission having a plurality of gear wheels. Each of the distribution cylinders has a spur gear. The plurality of distribution cylinders of the printing couple are driven, directly and jointly, by an engagement of each respective spur gear with a central gear wheel that is rotatable about a rotational axis. In an operating position, in which the central gear wheel is coupled into the path of power from the transmission, that central gear wheel is in direct toothed engagement with a gear wheel mounted on the rotational axis of the forme cylinder. 
     BACKGROUND OF THE INVENTION 
     An inking unit of a printing couple of a sheet-fed printing press is known from EP 1 930 161 A2. A plurality of oscillating ink rollers are driven directly and jointly by a central drive wheel. However, an additional oscillating ink roller is not driven directly by the central drive wheel. 
     A printing unit for a printing press having at least one printing couple is known from DE 195 20 841 A1. The printing couple comprises at least one forme cylinder and one transfer cylinder that interacts with this forme cylinder, and an inking unit having a plurality of distribution cylinders. The forme cylinder and/or the transfer cylinder and all the distribution cylinders of this printing couple are rotationally driven by the same drive motor. The distribution cylinders are driven by the drive motor by a transmission comprising a plurality of gear wheels. Each of the distribution cylinders has a spur gear. The plurality of distribution cylinders of this printing couple are driven directly and jointly by an engagement of each spur gear with a central gear wheel that is rotatable about a rotational axis. 
     A printing unit of an offset rotary printing press comprising two printing couples is known from DE 197 53 931 A1, wherein each of these printing couples has one forme cylinder and one transfer cylinder that interacts with said forme cylinder, wherein the transfer cylinders of these printing couples are engaged against one another, wherein each of the two printing couples has an inking unit with three distribution cylinders, wherein each of the distribution cylinders has a spur gear on its journal, wherein each of the respective spur gears of the distribution cylinders in the same inking unit is in direct toothed engagement with the same central gearwheel, wherein during print operation, each respective central gearwheel is in drive connection, via at least one intermediate gear, with a motor that drives at least one of the forme cylinders, wherein the relevant intermediate gear can be disengaged from the drive connection with the forme cylinder of the respective printing couple by an axial displacement, wherein the spur gears of the distribution cylinders of the same inking unit remain in engagement with their respective central gearwheel even after the intermediate gear has been disengaged from the drive connection to the respective forme cylinder. 
     From WO 02/076744 A1, a drive for a printing couple comprising a first cylinder embodied as a forme cylinder is known, wherein a second cylinder which interacts with the forme cylinder and an inking unit assigned to the forme cylinder are provided, wherein the drive of the two cylinders originates from the forme cylinder, which drives the second cylinder via a drive connection, wherein the inking unit is driven by the second cylinder via a drive connection, wherein the forme cylinder can preferably be driven mechanically independently of the drive of another printing couple by a drive motor, wherein the inking unit assigned to the forme cylinder is driven by means of the same drive motor, and wherein the drive connection between the second cylinder and the forme cylinder is embodied as a gear train. 
     From DE 10 2006 035 713 A1, an inking unit drive in a machine for processing print substrates, comprising an inking unit having a plurality of oscillating ink rollers, is known, wherein input applied from a printing press cylinder to a central inking unit drive wheel can be fed in, and can be output from this onto the rotationally and axially oscillating, drivable ink distribution rollers, wherein the inking unit drive wheel is disposed freely rotating on a stationarily mounted gear shaft, wherein a clutch is disposed on the gear shaft, fixed in position adjacent to the inking unit drive wheel, wherein when the clutch is in the engaged state, it is coupled with the inking unit drive wheel to allow the transfer of torque, and in the disengaged state it is uncoupled from the inking unit drive wheel, and wherein fixed in position on the gear shaft is an inking unit follower gear, with which output can be realized on the ink distribution rollers when the clutch is engaged. 
     From DE 10 2006 036 511 A1, a drive for an offset printing press is known, wherein in a gear train of this drive, a displaceable gear wheel is provided, wherein with this displaceable gear wheel, a flow of power from a gear wheel disposed non-rotatably on a shaft of a plate cylinder to a rotatable roller of an inking unit can be produced. 
     From CH 439 338 A, an inking unit for printing couples of rotary printing presses, which couples are operated in two directions of rotation, are known, wherein intermediate gears that can be disengaged are disposed in the inking unit drive. 
     From DE 24 58 772 A1, a rotary printing press having an inking unit is known, wherein during operation, the inking unit is driven by the press drive, and during washing, said unit is driven by an auxiliary motor, wherein the two drives can be separated from one another by a coupling on the plate cylinder shaft, wherein the drive wheel of the plate cylinder consists of two spur gears, which can be connected to one another via an electromagnetic tooth clutch, wherein the gear wheel that is engaged with the blanket cylinder drive wheel is disposed movably on the plate cylinder shaft, and the gear wheel that drives the inking unit gears is disposed non-rotatably on the plate cylinder shaft. 
     SUMMARY OF THE INVENTION 
     The problem addressed by the invention is that of devising a printing unit for a printing press that has at least one printing couple, and has a drive train that can be produced cost-effectively, wherein this drive train can be disposed in an installation space of low overall height. 
     The problem is solved according to the invention by the driving of all of the distribution cylinders of the printing couple directly and jointly by the central gear wheel. That central gear wheel is configured as an individual gear that has only a single ring gear. All of the gear wheels of the entire transmission are straight cut. 
     The advantages to be achieved with the invention consist particularly in that the printing couple of the printing unit is extremely compact in structure and has a drive train that can be cost-effectively produced. The transmission of the drive train requires only a small number of gear wheels, because the gear train is embodied as very short. Because the drive motor transfers its torque via only a small number of gear wheels, this transmission relatively highly efficient. Because the drive train originating from the drive motor ends at the spur gears of the distribution cylinders, no additional space-consuming gear wheels are provided in this drive train. The transmission of the drive train can therefore be implemented in an installation space having an overall height that occupies less than 80%, preferably less than 60%, of the overall height of the entire printing couple. The space that is gained as a result of the compactly structured transmission of the printing couple in and/or on the frame of the printing unit can advantageously be used for positioning other machine components that are required in the printing unit, i.e., particularly units and/or control elements and/or cable fittings, resulting in a novel concept for the structure and the configuration of this printing unit. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       One embodiment example of the invention is illustrated in the set of drawings, and will be specified in greater detail in what follows. 
       The drawings show: 
         FIG. 1  a roller configuration for a printing unit comprising two printing couples; 
         FIG. 2  a schematic illustration of a transmission for one of the printing couples illustrated in  FIG. 1 ; 
         FIG. 3  a perspective illustration of a section of the transmission of  FIG. 2 . 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIG. 1  shows, by way of example, a roller configuration of a printing unit  01  for an offset rotary printing press that is preferably used in commercial printing, comprising a plurality of printing couples  03 , particularly two, arranged one above the other vertically in the same frame  02 , for example, wherein each of these printing couples  03  has a forme cylinder  04  and a transfer cylinder  06  that interacts with said forme cylinder  04 , wherein the transfer cylinders  06  of these printing couples  03  are engaged against one another at least when this printing unit  01  is in print operation, wherein a print substrate  07  indicated in  FIG. 1  by a dashed line, for example, a web of print substrate  07 , particularly a paper web  07 , is guided essentially horizontally through this printing unit  01  in a direction of transport T between the transfer cylinders  06  engaged against one another. The forme cylinder  04  is covered on its outer surface by at least one printing forme, which preferably spans its entire circumference. At least one printing blanket, for example, a metal printing blanket, is secured on the outer surface of the transfer cylinder  06 . 
     Each of the two printing couples  03 , which are essentially structurally identical and configured as mirror images from the path of the print substrate web  07 , has an inking unit  08  with a plurality of distribution cylinders  09 , particularly three, wherein on one of these distribution cylinders  09 , ink that is drawn from an ink reservoir  11  assigned to the respective inking unit  08  to form an ink flow is divided into a main ink flow and a secondary ink flow, wherein the main ink flow and the secondary ink flow are fed, each via a single ink transfer roller  12 , to another of the two additional distribution cylinders  09 , for example, belonging to the respective inking unit  08 . In the preferred embodiment, the ink flow drawn from the ink reservoir  11  is fed to the center of the three distribution cylinders  09 , which are preferably arranged in a circular arch, particularly in a semicircle, wherein the respective centers of the distribution cylinders  09  in this arch are arranged offset from one another, for example, by approximately or at least 90°. 
     The ink reservoir  11  is embodied, for example, as an ink fountain  11 , having a plurality of ink keys, for example, more than twenty, arranged side by side, transversely to the direction of transport T of the print substrate  07 , wherein in each ink key, a controllable ink metering element  13 , particularly an ink blade  13 , is provided, which can be adjusted for metering the volume of ink to be delivered from the ink reservoir  11 , wherein ink held in the ink reservoir  11  is taken up, in a volume that is adjusted in the relevant ink key by the respective ink metering element  13 , by a rotatable ink fountain roller  14 , and is delivered, for example, to an ink film roller  16  disposed adjacent to the ink fountain roller  14 , for example. The ink film roller  16  transfers ink that is taken up by the ink fountain roller  14  over only a single ink transfer roller  17  to the specific distribution cylinder  09  that divides the ink flow received from the ink reservoir  11  into the aforementioned main ink flow and secondary ink flow. The ink fountain  11  can be pivoted against or pivoted away from the respective ink fountain roller  14 , which is mounted rotatably but fixed in position in the frame  02 , by actuating at least one lever  26 , for example, with both of these operating positions of the respective ink fountain  11  being indicated in  FIG. 1 . 
     Both the distribution cylinder  09  disposed in the main ink flow and the distribution cylinder  09  disposed in the secondary ink flow pass ink received from their respective ink transfer roller  12  on to the respective forme cylinder  04  via two ink forme rollers  18  each, wherein either in the main ink flow or in the secondary ink flow, one of the two ink forme rollers  18  can also be used as a dampening forme roller, if the relevant printing couple  03  is equipped with a dampening unit  19 , for example, a film dampening unit  19 , more particularly, a three-cylinder film dampening unit  19 . 
     The three distribution cylinders  09  of the inking unit  08  preferably have an outer surface made of a plastic, particularly made of Rilsan. The outer surfaces both of the ink transfer rollers  12  disposed between the distribution cylinders  09  and of all the ink forme rollers  18  are coated with rubber, i.e., with an elastomeric material. The ink film roller  16  also preferably has an outer surface made of Rilsan, wherein this outer surface is embodied, for example, as having a rhombic structure. The ink film roller  16  is mounted at both ends in the frame  02 , preferably so as to pivot on levers. The ink fountain roller  14  has an outer surface made of a ceramic, for example. Between the ink fountain roller  14  and the ink film roller  16 , a gap, the width of which is variably adjustable, is formed, with a preferred width of this gap being 0.08 mm. If a three-cylinder dampening unit  19  is provided, the center roller is embodied, for example, as a preferably non-oscillating dampness distributing roller  21 , with an outer surface made of chromium, which transfers a dampening agent picked up by a dampening fountain roller  22  from a dampening agent reservoir  23  to the ink forme roller  18  used as a dampening forme roller. 
     In the preferred embodiment of the inking unit  08 , all of the ink forme rollers  18  and ink transfer rollers  12 ;  17  and the ink film roller  16  are driven via friction. The ink fountain roller  14  is independently rotationally driven by a preferably electric drive motor  27 . The dampness distributing roller  21  of the dampening unit  19  is also independently driven by a preferably electric drive motor  28 , wherein this drive motor  28  also drives the dampening fountain roller  22  at a lower speed than the dampness distributing roller  21 , preferably via a gear train. 
     Each of the two printing couples  03  disposed in the same printing unit  01  has its own preferably electric drive motor  29  for its respective forme cylinder  04 , which motor is independent of the other printing couple  03 , wherein the speed and angular position of this drive motor  29  are preferably regulated by an electronic drive controller, which is connected at least for data transmission purposes to a virtual guide axis. The two printing couples  03  are therefore driven individually and separately from one another. 
     For one of the printing couples  03 , the assigned drive train, originating from the relevant drive motor  29 , is illustrated by way of example in  FIG. 2 . A level of torque provided by the respective drive motor  29  is preferably transferred directly and immediately, for example, without a clutch, via a pinion gear  32 , which is non-rotatably connected to the rotational axis  31  of this drive motor  29 , to a gear wheel  34 , which is non-rotatably connected to the rotational axis  33  of the forme cylinder  04 , whereby said forme cylinder  04  is rotationally driven or at least can be rotationally driven, particularly according to the specifications of the guide axis. To rotationally drive the transfer cylinder  06  that interacts with this forme cylinder  04 , a gear wheel  36 , which is non-rotatably connected to the rotational axis  37  of this transfer cylinder  06 , meshes with the gear wheel  34 , which is non-rotatably connected to the rotational axis  33  of the forme cylinder  04 . A transfer cylinder  06  of the other printing couple  03  of this printing unit  01 , which is engaged or at least can be engaged against the transfer cylinder  06  of this printing couple  03 , and which acts as the impression cylinder for the printing couple shown in  FIG. 2  in the illustration of the drive thereof, is not incorporated into the drive train of the former printing couple  03 , and is instead completely separate therefrom with respect to its drive. Pinion gear  32 , which is non-rotatably connected to the rotational axis  31  of the drive motor  29 , gear wheel  34 , which is non-rotatably connected to the rotational axis  33  of the forme cylinder  04 , and gear wheel  36 , which is non-rotatably connected to the rotational axis  37  of the assigned transfer cylinder  06 , are disposed essentially within the same first, preferably vertical plane, which is orthogonal to these rotational axes  31 ;  33 ;  37 , which are parallel to and spaced from one another. Alternatively, it is also possible to drive the transfer cylinder  06  directly and immediately, and then to incorporate the relevant forme cylinder  04  into the flow of power originating from the drive motor  29 . 
     A second gear wheel  38  is preferably non-rotatably disposed on the rotational axis  37  of the transfer cylinder  06  of the first printing couple  03 , illustrated by way of example in  FIG. 2 , wherein this second gear wheel  38  is in toothed engagement with a gear wheel  39  that is preferably mounted so as to rotate freely at least on the rotational axis  33  of the forme cylinder  04 . Alternatively, these two gear wheels  36 ;  38 , disposed on the rotational axis  37  of the same transfer cylinder  06 , can also be embodied as a single component comprising a double-width gear wheel, for example, or as a so-called double gear. 
     The gear wheel  39 , which is mounted so as to rotate freely at least on the rotational axis  33  of the forme cylinder  04 , and preferably also so as to slide axially on the rotational axis  33  of the forme cylinder  04 , can be brought immediately and directly into toothed engagement with a gear wheel  41 , which is non-rotatably connected to a rotational axis  47  and is centrally disposed in the inking unit  08 , wherein this gear wheel  41  disposed centrally in the inking unit  08  is in preferably permanent toothed engagement with at least one spur gear  42 , i.e., with a cylindrical gear wheel  42  that has teeth along its periphery, which spur gear  42  is non-rotatably connected to the rotational axis  43  of one of the three distribution cylinders  09 , for example, of the relevant inking unit  08 . The second gear wheel  38 , which is non-rotatably disposed on the rotational axis  37  of the transfer cylinder  06 , gear wheel  39 , which is mounted so as to rotate freely at least on the rotational axis  33  of the forme cylinder  04 , and gear wheel  41 , which is disposed centrally in the inking unit  08 , are disposed essentially within the same second plane E 2 , which is likewise preferably vertical, and is orthogonal to the stated rotational axes  37 ;  33 ;  47 , which are parallel to and spaced from one another, wherein this second plane E 2  is different from the above-described first plane E 1 . The two planes E 1 ; E 2  extend parallel to one another. 
     In the preferred embodiment, the spur gears  42  of all three distribution cylinders  09  of the relevant inking unit  08  mesh immediately and directly with gear wheel  41 , which is disposed centrally in the inking unit  08 , wherein all of these spur gears  42  are in preferably permanent toothed engagement with the gear wheel  41 , which is disposed centrally in the inking unit  08 . The spur gears  42  of the distribution cylinders  09  are therefore arranged in the manner of planetary gears around the gear wheel  41 , which is disposed centrally in the inking unit  08 . Gear wheel  41 , disposed centrally in the inking unit  08 , is embodied as a single gear, i.e., two or more gear wheels are not arranged on the rotational axis  47  thereof in the different parallel planes E 1 ; E 2  and orthogonal to the rotational axis  47 . 
     The drive train originating from the drive motor  29  of this printing couple  03  ends at the spur gears  42  of the distribution cylinders  09 , and therefore, no additional rotational bodies, i.e., rollers and/or cylinders of the relevant printing couple  03 , are incorporated with respect to drive into this drive train. The drive train is preferably embodied as a transmission  44 , more particularly, as a gear train  44 , as described in reference to  FIG. 2 , in which all interacting gear wheels  32 ;  34 ;  36 ;  38 ;  39 ;  41 ;  42  are straight cut, i.e., the gearing thereof is embodied as axially parallel. Because no helical-cut gear wheels are used in the gear train of the transmission in addition to the straight-cut gear wheels  32 ;  34 ;  36 ;  38 ;  39 ;  41 ;  42  or in place of these, this transmission  44  has no tooth advance, and therefore, certain gear wheels  39 ;  41 ;  42  can be axially displaced in a simple manner, wherein the gear wheel  39 ;  41 ;  42  to be displaced can remain in toothed engagement with at least one other gear wheel  38 ;  39 ;  41 ;  42 . The rotational axes  31 ;  33 ;  37 ;  43 ;  47  of all the gear wheels  32 ;  34 ;  36 ;  38 ;  39 ;  41 ;  42  interacting in this transmission  44  are arranged parallel with one another. Both the use of spur gears and the straight cut thereof contribute to the fact that this transmission  44  can be produced cost-effectively. The gear train of the transmission  44  is indicated in  FIG. 1  by dotted-dashed circles. The forme cylinder  04  is preferably mounted so as to be axially displaceable along an adjustment path ΔS for adjusting a lateral register in the frame  02 , wherein this adjustment path ΔS ranges between 1 mm and 5 mm, for example. It can be provided that the gear wheel  39 , which is mounted so as to rotate freely on the rotational axis  33  of the forme cylinder  04 , moves with it laterally along this axial adjustment path ΔS, and is therefore disposed fixed in position on the rotational axis  33  of the forme cylinder  04 . In order to keep the transfer cylinder  06  of the printing couple  03  in a specific angular position relative to the forme cylinder  04  that interacts with it, the transfer cylinder  06  is incorporated into the drive train that is formed by the transmission  44 , and into the resulting flow of force. In this printing couple  03 , a circumferential register of the forme cylinder  04  can be adjusted by means of the drive motor  29  that acts on this forme cylinder  04 , through the adjustment of a specific angular position of this forme cylinder  04 , carried out, for example, from a control panel belonging to the printing unit  01 . Therefore, helical teeth on at least one pair of interacting gear wheels  32 ;  34 ;  36 ;  38 ;  39 ;  41 ;  42  in the gear train of the transmission are not required for the purpose of adjusting the circumferential register. Instead, the preferably entirely straight teeth of the gear wheels  32 ;  34 ;  36 ;  38 ;  39 ;  41 ;  42  of this transmission  44  enable an adjustment of the lateral register of the forme cylinder  04  that can be carried out easily, because gear wheels  32 ;  34 ;  36 ;  38 ;  39 ;  41 ;  42  of the transmission  44  that interact in direct contact can each be displaced axially and therefore axially parallel to one another, without affecting the circumferential register of the forme cylinder  04 . 
     Gear wheel  41 , which is disposed centrally in the inking unit  08 , is preferably embodied as an individual coupling wheel  41 , which can be displaced linearly along its rotational axis  47  by means of a controllable, for example, pneumatic positioning element  46 , for example, a pneumatic cylinder  46 , along an adjustment path ΔL, thereby allowing this coupling wheel  41  to be coupled into or uncoupled from a flow of power from the transmission  44 . The positioning element  46  can be controlled, for example, from the control panel belonging to the printing unit  01 . Independently of the displacement of the central gear wheel  41 , i.e., independently of the operating position thereof, said wheel remains permanently in toothed engagement with the respective spur gear  42  of each distribution cylinder  09 .  FIG. 2  shows the two operating positions of the central gear wheel  41 , wherein the operating position of the central gear wheel  41  after it has been uncoupled from the flow of power from the transmission  44  is indicated by dashed lines. The embodiment of the gear wheel  41  disposed centrally in the inking unit  08  as an individual wheel having only a single ring gear is naturally more advantageous than the embodiment thereof as a double wheel with two ring gears disposed offset from and parallel to one another on the same rotational axis  47 . 
     Because only a small number of gear wheels  32 ;  34 ;  36 ;  38 ;  39 ;  41 ;  42  are integrated into the transmission  44 , and because in the operating state in which the central gear wheel  41  is coupled into the flow of power from the transmission  44 , said gear wheel is in direct toothed engagement with a gear wheel  39  that is mounted on the rotational axis  33  of the forme cylinder  04 , this transmission  44  has an installation space having an overall height H 2  of less than 80%, particularly less than 60%, of the overall height H 1  of the printing couple  03 , wherein the overall height H 1  of the printing couple  03  in the printing unit  01  illustrated by way of example in  FIG. 1  is approximately half the height of the frame thereof. This low installation space for the transmission  44 , in turn, contributes to the fact that a very compact printing unit  01  can be realized, because space is gained in and/or on the frame  02  of the printing unit  01 , which can be advantageously used for arranging other units and/or control elements and/or cable fittings, particularly electric and/or pneumatic lines, which are required in this printing unit  01 . For instance, particularly the drive motor  27  for the ink fountain roller  14  can be located outside of the installation space of the transmission  44 . In contrast, the drive motor  28  for the dampening unit  19 , i.e., particularly a pinion gear connected to a rotational axis of said drive motor  28  and/or a jointed shaft connected to the rotational axis of said drive motor  28 , preferably projects into the installation space of the transmission  44 . 
     In print operation and therefore in the operating setting in which the gear wheel  41  that is disposed centrally in the inking unit  08  is engaged with the drive train, the circumferential speed of the distribution cylinders  09  is faster or slower than the circumferential speed of the transfer cylinder  06 , and therefore, slippage is formed between the respective distribution cylinder  09  and a friction-driven roller  12 ;  17 ;  18  that is adjacent to the relevant distribution cylinder  09 , wherein this slippage is preferably less than 0.5%. The faster or slower speed than the distribution cylinders  09  is adjusted via a gear ratio resulting from the ratio of the number of teeth on the spur gear  42  of the relevant distribution cylinder  09  to the number of teeth on the second gear wheel  38 , disposed non-rotatably in the same plane E 2  on the rotational axis  37  of the transfer cylinder  06 . 
       FIG. 3  shows a perspective illustration of a section of the transmission  44 , wherein the central gear wheel  41  and the three spur gears  42  of the distribution cylinders  09  grouped around this central gear wheel  41 , along with the gear wheel  39  that is mounted on the rotational axis  33  of the forme cylinder  04  and can be brought into toothed engagement with the central gear wheel  41 , are shown in simplified form. In the interest of clarity, the distribution cylinders  09  and the forme cylinder  04  itself, along with the respective axial journals thereof that support the assigned gear wheels  39 ;  42 , are not shown in  FIG. 3 , and instead, only the respective rotational axes  33 ;  43  thereof are indicated by dotted-dashed lines. 
     Gear wheel  39 , which can be placed in toothed engagement with the central gear wheel  41  and is mounted on the rotational axis  33  of the forme cylinder  04 , has an axial width B 1 , particularly an edge width B 1 , which is less than one-half an axial width B 2 , for example, more particularly, edge width B 2  of the spur gears  42  of the distribution cylinders  09 . The edge width B 2  of the spur gears  42  of the distribution cylinders  09  ranges, for example, from 60 mm to 100 mm, whereas the edge width B 1  of gear wheel  39  mounted on the rotational axis  33  of the forme cylinder  04  ranges, for example, from 10 mm to 50 mm. The rotational axes  33 ;  43 ;  47  of the gear wheels  39 ;  42  that interact with the central gear wheel  41  are arranged parallel with one another. 
       FIG. 3  also shows positioning element  46 , which can be used to couple the central gear wheel  41  with the flow of power from the transmission  44 , i.e., placing it in toothed engagement with the gear wheel  39  that is mounted on the rotational axis  33  of the forme cylinder  04 , and/or to uncouple it from this power flow. By a particularly remotely triggered actuation of the positioning element  46 , the central gear wheel  41 , shown in  FIG. 3  in its engaged operating position, is displaced linearly along its rotational axis  47  along the adjustment path ΔL, thereby bringing this central gear wheel  41  out of engagement with the gear wheel  39  mounted on the rotational axis  33  of the forme cylinder  04 , wherein the central gear wheel  41  remains in toothed engagement with the spur gears  42  of the distribution cylinders  09  that are grouped around the central gear wheel  41 , due to their respectively greater, i.e., at least twice as large, edge width B 2 . The adjustment path ΔL ranges from 15 mm to 40 mm, for example. The positioning element  46  is embodied, for example, as a dual-action operating cylinder, or, if it is embodied as a single-action operating cylinder, the engagement process executed by the positioning element  46  can run counter to the force of a spring element, so that the central gear wheel  41  remains in the operating state brought about by the positioning element  46  only as long as the actuation of this positioning element  46  persists. Once the actuation of the positioning element  46  ceases, the force of the spring element pushes the central gear wheel  41  back to its operating state prior to actuation of the positioning element  46 . Alternatively, the positioning element  46  can actively displace the central gear wheel  41  alternately into the two operating states thereof. In the operating state in which the central gear wheel  41  is brought out of engagement with gear wheel  39 , which is mounted on the rotational axis  33  of the forme cylinder  04 , the inking unit  08  is placed in idle status, and therefore does not function. 
     As is also clear from  FIG. 3 , the three distribution cylinders  09  and the gear wheel  39  mounted on the rotational axis  33  of the forme cylinder  04  are arranged around the central gear wheel  41 , each at an offset ranging from 60° to 120°, preferably ranging from 70° to 110°, particularly about 90°. The spur gears  42  of the distribution cylinders  09  each have a diameter ranging from 120 mm to 150 mm, for example. The diameter of the central gear wheel  41  ranges, for example, from 120 mm to 400 mm, preferably ranging from 150 mm to 300 mm, particularly ranging from 150 mm to 200 mm. In print operation, the three distribution cylinders  09  each execute, for example, an oscillating movement, wherein these three distribution cylinders  09  oscillate opposite one another, with their movements relative to one another being offset preferably by one-third, for example, of a total stroke AR that can be executed by each of the three distribution cylinders  09 , or of a revolution of a crank wheel (not shown) that drives the oscillating movement of the distribution cylinders  09 . The total stroke ΔR that can be executed by each of the three distribution cylinders  09  ranges, for example, from 10 mm to 50 mm. 
     While a preferred embodiment of a printing unit of a printing press having at least one printing couple, in accordance with the present invention, has been set forth fully and completely hereinabove, it will be apparent to one of skill in the art that various changes could be made in, for example, the sizes of the cylinders, the number of distribution cylinders, the drive motor and the like, without departing from the true spirit and scope of the present invention which is accordingly to be limited only by the appended claims.