Abstract:
A printing unit of a printing press includes at least two frame parts whose distance from each other can be varied. Each of these frame parts include two laterally spaced frame plates. The two frame plates in each of the frame parts accommodate at least one cylinder or roller which extends between them. The two lateral frame plates in each frame part are spaced from each other in an axial direction of the supported cylinder or roller. Adjacent ones of the frame parts are connectable to each other by abutting of their respective lateral frame plates. At least three locking and/or centering devices are used to align and to lock together the lateral frame plates of adjacent ones of the frame parts.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This patent application is the U.S. National Phase, under 35 USC 371, of PCT/EP2004/050651, filed Apr. 29, 2004; published as WO 2005/037553 A1 on Apr. 28, 2005 and claiming priority to DE 103 47 571.0, filed Oct. 14, 2003, the disclosures of which are expressly incorporated herein by reference. 
   FIELD OF THE INVENTION 
   The present invention is directed to printing units of a printing press Each printing unit includes at least two frame elements whose distance, in relation to each other, can be changed. Each of these frame elements has two laterally spaced frame plates which support at least one cylinder or roller. 
   A printing unit is known from EP 0 749 369 B1, in which rollers are mounted in the movable frame element and rest on horizontal rails. These rollers also support the stationary frame element. In a printing unit of dimensions suitable for newspaper printing, the load resting on each roller of the movable frame element can reach an amount of several tons. Thus, extreme pressures occur at the contact faces between the rollers and rails on which they roll. While the rollers can be made of hardened steel, which can withstand being subjected to the occurring pressures, use of this hardened steel is difficult, in connection with the rails, because of their dimensions. However, if the rails are made of non-hardened steel the danger arises that the wheels may be pressed into the rails and it becomes impossible to move the movable frame element evenly, or to put it into motion at all. 
   U.S. Pat. No. 5,060,569 discloses a frame element which can be moved on rollers. The rails are raised for movement and the frame element rests on another frame element during operations. 
   EP 1 149 694 A discloses a printing press with movable frame elements. These frame elements are locked by hooks. 
   SUMMARY OF THE INVENTION 
   The object of the present invention is directed to providing printing units of a printing press. 
   In accordance with the present invention, this object is attained by the provision of a printing unit having at least two frame elements whose distance, in relation to each other, can be changed. Each of the frame elements has two laterally spaced frame plates which cooperate to support at least one cylinder or roller. The frame plates are spaced laterally from each other in a direction of an axis of rotation of the cylinder or roller. At least three locking and/or centering devices are used to fix in place the lateral frame plates of adjacent ones of the frame elements. The centering and locking devices can be positioned directly adjoining each other. One of the frame elements can be moved vertically with respect to the other. 
   Because of the retractability of the rollers, the possibility of displacing a weight resting on them at least partially to a contact surface different from the rollers is provided. The rollers are, in this way, relieved of the weight resting on them to the extent that the pressing of the rollers into a support need no longer be feared. 
   Since such a contact surface can easily be made larger than the contact surface which exists between a roller and a support, it is possible to decrease weight related pressure loads, even if the entire weight of the movable frame element is displaced to the contact surfaces which are different from the rollers. The demands made on the load carrying capability of a support on which the movable frame element is supported can be reduced. 
   The rails, on which the rollers rest in the extended state, are preferably also used as supports on which the contact surfaces, which are different from the rollers, are supported. 
   The contact surfaces can be constituted simply by the lower edges of lateral frame plates of the movable frame element. 
   Preferably, each frame element has at least one rubber blanket cylinder as the cylinder delimiting the printing gap, a forme cylinder and an inking system, so that the two rubber blanket cylinders, forme cylinders, and the like each constitute a printing unit in bridge construction suitable for recto- and verso-printing. 
   The displaceability of the rollers between their extended and the retracted positions is preferably achieved wherein each rotatable shaft of the associated roller is pivotably maintained on the movable frame element. A pneumatic or a hydraulic actuating member is preferably employed for driving at least one of the rollers in a pivot movement around its eccentric axis. 
   If two rollers, which can respectively be pivoted around a common eccentric axis, are arranged on a common torsion-proof shaft, a single actuating member can be employed for accomplishing the pivoting of both of the rollers. Tilting of the printing unit, during the retraction and extension of the rollers, can thus be avoided. 
   In connection with a movable frame element with two lateral frame plates, the two rollers, which can be pivoted around a common eccentric axis, are arranged in such a way that they each support different one of these frame plates. 
   Several rollers, and in particular those rollers which are running on a common rail or which are supporting the same frame plate, can be pivotably coupled by the use of a rod, which rod acts on shafts of the rollers via levers. 
   To fix the positions of the two frame elements in relation to each other in a working position, where they are not spaced apart, a protrusion is preferably formed on one of the frame elements. This protrusion is oriented in the movement direction of the movable frame element. A cutout, which is shaped in a complementary manner to the protrusion, is formed on the other frame element. The protrusion and the cutout will come into positive engagement with each other when the frame elements are arranged without a space between each other. 
   The protrusion or the cutout can automatically provide a centering effect when the frame elements are brought together. This is particularly effective if the protrusion is tapered towards its free end and/or the cutout tapers toward a bottom. 
   The protrusion is preferably shaped as a vertically oriented rib. The cutout is preferably shaped as a vertically oriented groove in order to define the position of the two frame elements relative to each other only in a horizontal direction transversely to the movement direction, but not in the vertical direction. 
   For use in guiding the movement of the movable frame element, least one upright guide rail is preferably provided. This guide rail extends in the movement direction of the movable frame element, is fixedly connected with one of the frame elements and is enclosed on two sides by a track guidance device of the other frame element. This track guidance device is preferably comprised of at least one pair of guide rollers, which roll off on the sides of the guide rail. 
   For use in moving the movable frame element, a toothed rack, which is extending in the movement direction of the movable frame element, is suitably mounted on one of the frame elements. On the other frame element, a self-locking drive mechanism is used to engage the toothed rack, which self-locking drive mechanism can be disengaged from the toothed rack in order not to block the movement of the movable frame element in case of an interference. The greatly geared-down drive mechanism is preferably accomplished with the aid of a worm gear. This worm gear drive is preferably pivotably attached to the frame for disengagement from the toothed rack. 
   To lock stationary and movable frame elements of the printing group together in their work position, at least one hook is preferably provided on one of the frame elements, which at least one hook can be brought into engagement with the other frame element. This at least one hook can be charged with a pulling force that is acting in a direction toward the one frame element. Preferably, the movable frame element is identical to the previously mentioned movable frame element, in addition to the frame element fixed in place on the frame, the stationary frame element can also include the support. 
   The hook preferably engages a roller of the other frame element. The hook&#39;s movement into the engagement position and out of the engagement position is not hampered by too strong frictional forces. A pneumatic or a hydraulic actuating member is preferably used for driving the hook in a pivot movement into the engagement position or out of it. The supply of the actuating member with pressure fluid is simplified if the frame element, to which the hook and the actuating member are attached, is the stationary frame element. 
   At least one hook should exert a pulling force, with a downward directed component, on the movable frame element in order to fix the latter in place also in the vertical direction. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Preferred embodiments of the present invention are represented in the drawings and will be described in greater detail in what follows. 
     Shown are in: 
       FIG. 1 , a schematic side elevation view of a printing group with a movable frame element which is spaced apart from a stationary frame element, in 
       FIG. 2 , the printing group depicted in  FIG. 1 , with the movable frame element in a position wherein it is not spaced apart from the stationary frame element, and with rollers extended, in 
       FIG. 3 , the printing group in  FIG. 1  with the rollers retracted in a work position, in 
       FIG. 4 , a schematic depiction of the suspension of the rollers from a lateral frame plate of the movable frame element, in an extended position, in 
       FIG. 5 , a schematic depiction of the movable frame element, with the rollers in the retracted position, in 
       FIG. 6 , a perspective view, from above, of a running gear of the movable frame element, as well as of rails of the stationary frame element on which the running gear moves, in 
       FIG. 7 , a schematic cross-sectional view through a wheel box of the running gear in accordance with  FIG. 6 , in 
       FIG. 8 , a drive mechanism for use in accomplishing the movement of the movable frame element along the rails, in 
       FIG. 9 , a schematic cross-sectional view through the drive mechanism depicted in  FIG. 8 , in 
       FIG. 10 , a schematic plan view of a locking mechanism for locking the frame elements together, in 
       FIG. 11 , a partial cross-sectional view, from above of the locking mechanism shown in  FIG. 10 , in 
       FIG. 12 , a schematic plan view of a locking mechanism for use in locking the movable frame element on the support, in 
       FIG. 13 , a schematic representation of a printing group with two movable frame elements and with one frame element fixed in place, and in 
       FIG. 14 , a schematic representation of a locked position of a printing unit in accordance with  FIG. 13 . 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIGS. 1 to 3  illustrate the basic operative principle of the present invention. A printing unit is shown and which is provided with four printing groups, which printing groups are arranged one above the other and which each have pairs of cylinders  01 , such as, for example, rubber blanket cylinders  01  or rollers. In a manner which is known per se, a plate cylinder, an inking system and a dampening system are assigned to each rubber blanket cylinder  01 . These cylinders and systems are maintained between respective lateral frame plates  02 ,  03 . The interior structure of the printing groups will not be described in detail here, since such a description is not required for an understanding of the present invention. A description of this type of interior structure is provided in EP 0 749 369 B1, to which reference is hereby made. 
   The two spaced lateral frame plates  02 , together with the cylinders  01  and the inking and dampening systems which they support, form a fixed frame element  13 . This frame element  13  is fixed on a press main frame and is solidly mounted between upper and lower supports  04 ,  06  of that main press frame. The two spaced lateral frame plates  03 , together with the cylinders  01 , inking and dampening systems which they support, form a movable frame element  15 . These two spaced lateral frame plates  03  are fixedly mounted between the upper and lower supports  04 ,  06 , which are respectively constructed with parallel rails  05  which are transversely connected with each other, as may be seen in  FIGS. 6 and 12 . The two spaced lateral frame plates  03  are provided with rollers  07  on their lower edge, which rollers  07  can be displaced between an extended position and a retracted position. The two frame plates  03 , together with the components maintained between them, form a movable frame element  15 .  FIG. 1  shows the rollers  07  in their extended position, in which extended position, rollers  07  keep the lateral frame plates  03  spaced apart from the rails  05  of the lower support  06 . These rails  05  are, at the same time, used as a track, on which the rollers  07  roll off. 
     FIG. 1  shows the movable frame element  15  in an open or separated position in which it is spaced apart from the lateral frame plates  02  and in which spaced apart position an operator  08  can enter a space between the pairs of rubber blanket cylinders  01  and can perform maintenance work, such as a change of rubber blankets. Following the completion of the maintenance work, the movable frame element  15  is displaced toward the left in  FIG. 1  until it reaches the closed or contiguous position represented in  FIG. 2 , in which closed position the stationary lateral frame plates  02  and the movable lateral frame plates  03  touch each other at respective edges  09 ,  11  that are facing each other. In this closed position, with rollers  07  still extended, the rubber blanket cylinders  01  of the movable lateral frame element  15  lie slightly higher than those of the stationary one. By bringing the rollers  07  into their retracted position, in which they no longer protrude past the lower edge of the lateral frame plates  03 , the movable frame element  15  is lowered a further distance, as represented in  FIG. 3 , so that the lower edges of the lateral frame plates  03  now lie on the rails  05  of the support  06 . In this closed, engaged position, the pairs of rubber blanket cylinders  01  respectively arrive at the same height and form a printing gap, in which a web  12  of material, such as, for example, a paper web  12 , which is conducted between the blanket cylinders  01 , can be imprinted. 
   While in the positions shown schematically in  FIGS. 1 and 2 , the rollers  07  support the entire weight of the movable frame element  15 , including that of the lateral frame plates  03  and the cylinders  01  of the several printing groups which are held between them, and transfer that weight to a small surface of the lower support  06 . In the position depicted schematically in  FIG. 3 , in which the entire lower edge of the lateral frame plates  03  rests on the lower support  05 , the weight is distributed over a substantially greater area than the area which receives that weight when the frame element  15  is supported only by the rollers  07 . The rollers  07  thus support the movable frame element  15  only when it is to be moved, and possibly if, as represented in  FIG. 1 , the movable frame element  15  is spaced apart from the stationary frame element  13  and the space between the frame elements  13 ,  15  is accessible. This spacing, and weight support by rollers  07  is occasioned only during comparatively short periods of time. During a printing operation, the lateral frame plates  03  rest with their lower edges on the lower support  06 . Thus, there is no danger that the rollers  07  will press into the lower support  06 , or that the rails  05  of the lower support  06  are damaged in other ways, so that the mobility of the movable frame element  15  would be hindered by this type of damage. 
   A preferred mechanism for retracting and for extending the rollers  07  is represented schematically in  FIGS. 4 and 5 .  FIG. 4  shows the rollers  07  in the extended position, and  FIG. 5  shows the rollers  07  in the retracted position. The rollers  07  have a rotatable shaft  14 , which is hinged by the use of a first, pivot lever arm  17  on a pivot shaft  16 , which pivot shafting is stationary with respect to the lateral frame plate  03 . A second, actuating lever arm  18  is rigidly connected, at one end, with the first, pivot lever arm  17  of a right roller  07 . A free end of actuating lever arm  18  engages a piston rod  19  of a pneumatic or a hydraulic actuating member  21 , such as, for example, a hydraulic cylinder  21 . One end of a rod  22 , for example a synchronizing rod  22 , is hinged to a free end of a third lever arm  23 , which is rigidly connected with the first, pivot lever arm  17  of the left roller  07 . A second end of synchronizing rod  22  is hinged to an intermediate point on the second, actuating lever arm  18 . The distance of the intermediate point from the adjoining eccentric shaft  16 , such as, for example, the pivot shaft  16 , corresponds to the length of the third, working lever arm  23 , so that the second and third lever arms  18 ,  23 , which are coupled to each other by the synchronizing rod  22 , always perform the same rotating movement. In the position depicted in  FIG. 4 , a first chamber  26  of the hydraulic cylinder  21 , which is facing away from the piston rod  19 , has been put under pressure, so that the piston rod  19  is extended out of actuating member  21  as far as a stop and this maintains the rollers  07  in the extended position. The piston rod  19  is slowly retracted, into member  21 , by the controlled release of pressure gas from the chamber  26 . The rollers  07  pivot in a counterclockwise direction around their pivot shafts  16  until the lower edge of the lateral frame plate  03  rests on the support  06 . When the rollers  07  are in the retracted position, in which they rest loosely on the support  06 , they can be lifted off the support  06  into the position represented in  FIG. 5  by charging a second chamber  27  of the hydraulic cylinder  21 , which second chamber  27  is facing the piston rod  19 . 
     FIG. 6  shows a detailed representation of a running gear of the movable frame element  15 , as well as of two rails  05  of the lower support  06  on which the running gear can be moved. The previously described hydraulic cylinder  21 , the piston rod  19  and the actuating lever arm  18  can be seen in  FIG. 6 . The end of the hydraulic cylinder  21 , which is facing away from the piston rod  19 , is connected with a horizontal arm  28  that is extending from a flange  29 , from whose side facing away from horizontal arm  28 , four pins  31  project. These pins  31  are screws  31 , which are used for securing the flange  29  to one of the two lateral frame plates  03  of the movable frame element  15 , which lateral frame plates  03  are not represented in  FIG. 6 . Corresponding pins  32 , or screws  32 , that are used for the same purpose, protrude past the lateral walls of two wheel boxes  33 ,  34 . Each one of the wheel boxes  33 ,  34  contains one of the previously discussed rollers  07 . 
   A schematic section through the wheel box  34  is represented in  FIG. 7 . The location of the pivot shaft  16  is indicated by a cross. It is also the longitudinal axis of a shaft  36 , for example a pivot shaft  36 , which is extending transversely through the wheel box  34 , at which point the actuating lever arm  18 , which is connected with the piston rod  19 , acts on the pivot shaft  36  outside of the wheel box  34 . The first, pivot lever arm  17  is realized by an eccentric sleeve  37 , whose interior bore encloses the pivot shaft  36  and is fixed to pivot shaft  36  against relative rotation, and whose exterior circumference supports the roller  07  by the use of a bearing  38 , such as, for example, a rolling bearing  38 . The center of the exterior circumference of the sleeve  37 , which defines the axis of rotation of the roller  07 , is identified by a cross at  39 , as seen in  FIG. 7 . If the lever arm  18  is rotated in a clockwise direction, the center of sleeve  37  and of the rotatable shaft  36  moves along the arrow  41 , so that a portion of the running face of the roller  07  emerges from the open underside of the wheel box  34 . 
   As is shown in  FIG. 6 , the pivot shaft  36  extends, starting at the wheel box  34 , transversely underneath the movable frame element  15  and crosses through a second wheel box  42 , on which a second roller  07  is mounted in the same way as in the first wheel box  34 . The second roller is positioned on the second lateral frame plate  03  in a manner the same as is used to secure the first roller  07  and the first wheel box  34  to the first lateral frame plate  03  of the movable frame element  15 . 
   The synchronizing rod  22  acts on the one hand via a working lever arm  43 , and on the other hand via the lever arm  23 , on the pivot shaft  36 , as well as on a second shaft  44 , for example a second pivot shaft  44 , which is parallel with the first pivot shaft  36  and which passes through the wheel boxes  46  and  33 . The movements of all of rollers  07  between the extended or retracted position are coupled to each other by the synchronizing rods  22  and by the continuous rigid pivot shafts  36 ,  44 . 
   A guide rail  47 , which is provided with an F-shaped cross section, is rigidly connected with the two wheel boxes  33 ,  34 , as seen in  FIG. 6 . This guide rail  47 , which can be displaced together with the movable frame element  15 , has a vertically downward directed rib  48  which, in case of a displacement of the frame element  15 , moves with contact between two pairs of guide rollers  49 . These guide rollers  49  are mounted on one of the support rails  05  and are remote from a rolling surface of the support rail  05  over which the rollers  07  move. The cooperation between the guide rail  47  and the guide rollers  49  enforces an exactly linear movement of the movable frame element  15  along the support rails  05 , without the possibility of an offset of the movable frame element  15  transversely to the longitudinal direction of the rails  05 . Although they are not specifically represented, a corresponding guide rail  47  and guide rollers  49  can also be mounted on the wheel boxes  42 ,  46 , or on the lower support  06  of the main press frame which, as depicted in  FIG. 6 , faces the viewer. 
   The drive mechanism, which is represented in a perspective plan view in  FIG. 8 , is mounted on the running gear, or on one of the lateral frame plates  03  mounted thereon, of the movable frame element  15 . Two rigid arms  51  project transversely, with respect to the movement direction of the movable frame element  15  away from the running gear, or away from one of the lateral frame plates  03 . Between them, these arms  51  support a drive unit  53 , which is hingedly suspended from a shaft  52  and which drive unit  53  has a motor  54 , such as, for example, an electric motor  54 , which electric motor  54  drives an output gear wheel  56  via a self-locking reduction gear which is housed in the drive unit  53 . In the position of the drive unit  53 , depicted in  FIG. 8  the output gear wheel  56  meshes with a stationary toothed rack  57 . 
     FIG. 9  shows a cross-section through the drive mechanism depicted in  FIG. 8 . The drive unit  53  is supported by a projection  58  of a pivot lever handle  59  which is hinged on one of the arms  51 . The gear wheel  56  is maintained in engagement with the toothed rack  57  by this support of the drive unit  53 . If the pivot lever handle  59  were lifted, the drive unit  53  could pivot in a clockwise direction around the shaft  52  and in this way could move the gear wheel  56  out of the toothed rack  57 . This will cancel the non-positive connection between the electric motor  54  and the toothed rack  57 . 
   A drive gear wheel  61 , which is directly driven by the electric motor  54  and which meshes with a larger driven gear wheel  62 , is located inside the drive unit  53 . Driven gear wheel  62  is mounted on a common shaft together with a worm  63 , which, in turn, meshes with a worm wheel  64 . This worm wheel or gear  64  is mounted on a common shaft with the gear wheel  56 . The worm  63  and the worm wheel  64  cause self-locking of the gear, by means of which the output gear wheel  56  is arrested when the electric motor  54  is switched off. 
     FIG. 10  shows a portion of one of the stationary lateral frame plates  02  and a portion of one of the movable lateral frame plates  03 , whose vertical edges  09 ,  11  touch each other in the closed, engaged operating position of the printing unit. A mechanism for locking the lateral frame plates  02 ,  03  with each other in the operating position is shown in  FIG. 10 . This locking mechanism includes a pivotable hook  66 , which is hinged to a forked bearing block  67 , as is shown in section in  FIG. 10 . Two bores  68  are used for screwing or otherwise attaching the bearing block  67  on the lateral frame plate  02 . These bores  68  permit limited horizontal play of the bearing block  67 . In spite of measurement tolerances of the hook  66  and of the lateral frame plates  02 ,  03 , this limited horizontal play allows the exact placement of the bearing block  67  in such a way that an interior flank  69  of the hook  66  extends around a locking protrusion  71  on the movable lateral plate  03  with exact contact. The radius of the interior flank  69  of the hook  66 , in relation to the pivot shaft of the hook  66  on the bearing block  67 , is slightly decreased in a counterclockwise direction. The interior flank  69  of hook  66  is thus capable of extending behind the locking protrusion  71 , even if the edges  09 ,  11  of the lateral frame plates  02 ,  03  do not directly touch each other. The two lateral frame plates  02 ,  03  are then pulled against each other by pivoting the hook  66  in a clockwise direction until edges  09 ,  11  touch each other in the contact position shown in  FIG. 10 . The pivot movement of the hook  66  is driven by an actuating member  72 , such as, for example, a pneumatic cylinder  72 . 
   The locking protrusion  71  is constituted by a central pin  73 , which is fixedly connected with the lateral frame plate  03 , and by a roller  74  that is seated in a roller bearing and which is surrounding the pin  73 . This roller  74  can turn or rotate when the hook  66  is pressed onto the locking protrusion  71 , so that, in spite of the considerable tractive forces which the hook  66  can exert on the locking protrusion  71  in the course of pivoting of the hook  66 , the movement of the hook  66  is not blocked by too much friction. 
   To prevent the bearing block  67  from slipping on the lateral frame plate  02  about its connection through bores  68 , so that sufficient tractive force would no longer be able to be exerted on the locking protrusion  71 , the bearing block  67  is additionally secured by two securing screws  76 . These securing screws  76  are screwed into the bearing block  67  from the direction of a retaining block  77  which is rigidly fastened to the plate  02 .  FIG. 10  shows these two securing screws  76  tightened until they make contact, so that the bearing block  67  touches the retaining block  77 . If the securing screws  76  are loosened a little, it is possible to place the bearing block  76  a little closer to the edge  09  and to fix it in place on the lateral frame plate  02  with the aid of screws entering into the bores  68 . 
     FIG. 11  shows the locking mechanism of  FIG. 10  partially in a view from above and partially in cross-section. The pneumatic cylinder  72  and the hook  66 , which it hingedly engages, can be seen. Two depressions have been formed at the touching edges  09 ,  11  of the lateral frame plates  02 ,  03 . An insertion body  78 , with a vertical cutout  79 , such as, for example, a groove  79  of a trapezoidal cross section, is screwed into the depression of the lateral frame plate  02 . An insertion body  81  with a protrusion  82 , such as, for example, a rib  82  which positively engages the groove  79 , is housed in the recess of the lateral frame plate  03 . The insertion body  81  is simultaneously used as a support for the pin  73  and for the roller  74  of the locking protrusion  71 . 
   The rib  82  and the cooperatively shaped groove  79  provide an exactly flush alignment of the lateral frame plates  02 ,  03 , with respect to each other, transversely to the movement direction of the movable frame element  15  when they touch each other in the closed, engaged operating position of the printing unit. In order to avoid redundancy, insertion bodies  81  with the groove  79  and rib  82  are only provided at one of the two lateral frame plates  02 ,  03  of the stationary frame element  14  or the movable frame element  15 , respectively. The insertion bodies which are attached to the other respective lateral frame plate  02 ,  03  are flat on their facing sides. The rib  82  and the groove  79  permit a vertical movement of the lateral frame plates  02 ,  03  against each other in the course of the transition of the rollers  07  between the retracted and the extended positions. 
     FIG. 12  shows two hooks  83 , which are respectively provided in pairs on the two lower supports  06  of the main press frame. A first hook  83 , which is formed with a ramp-shaped upper side, is pivotable around a shaft  84  which is situated adjacent an edge  09  of the lateral frame plate  02  and which first hook  83  has a notch  86  on its upper side. This notch  86 , in the locked state of the first hook  83 , receives a locking protrusion  87  carried on the lateral frame plate  03 . The structure of the locking protrusion  87  is the same as that of the locking protrusion  71  discussed above. An actuating member  88 , such as, for example, a pneumatic cylinder  88 , which is mounted, substantially horizontally oriented, on the lower support  06  of the main press frame, is used for locking and unlocking the hook  83 . The piston rod of the pneumatic cylinder  88  is hinged to a first rod  89 , which acts on the hook  83 , and to a second rod  91 , whose second end is, in turn, hinged to the support  06  and which second rod  91  forms an angle with the first rod  89 . When the piston rod is retracted from the extended position represented in  FIG. 12 , the angle between the first and second rods  89 ,  91  is reduced. The result is that the point of engagement of the rod  89  at the hook  83  is lowered, and the locking protrusion  87  is released. The movable frame member  15  can now be shifted. 
   In a manner which is the same as discussed in connection with the pneumatic cylinder  88 , a second actuating member  92 , such as, for example, a pneumatic cylinder  92 , is substantially horizontally oriented on the support  06 . Pneumatic cylinder  92  has a piston rod which acts via two rods  93 ,  94 , which are angled in relation to each other in a manner similarly to the rods  89 ,  91 , on the support  06  and on a second hook  96 . Like the first pivotable hook  66 , this second pivotable hook  96  has an interior flank  97  which flank  97 , in the course of extending the second hook  96 , slides along a locking protrusion  98  of the lateral frame plate  03  and, in the process, exerts a tractive force on the locking protrusion  98 , which tractive force is directed downward and in the direction toward the lateral frame plate  02 . This tractive force becomes larger the closer the hook  96  is to its contact position represented in  FIG. 12 . The hook  96  thus exerts a double locking function. For one, it keeps the lateral frame plate  03  pressed against the lateral frame plate  02 . It also maintains the frame plate  03  fixed on the support  06 . 
   The three pivotable hooks  66 ,  83 ,  96  can each be actuated by the use of a toggle lever, for example. 
   In another preferred embodiment of the present invention, as seen in  FIG. 13  and in  FIG. 14 , the printing unit has three frame elements  104 ,  106 ,  107 , wherein forme cylinders and transfer cylinders are arranged in the center frame element  106 . Inking systems, which are assigned to the forme cylinders, are arranged in the two outer frame elements  104  and  107 . 
   As represented in  FIG. 13 , the two outer frame elements  104  and  107  can be moved into a maintenance or set-up position, so that an accessible space between them and the fixed, center frame element  106  is provided. 
   The combined, closed, operating state of these three frame elements  104 ,  106 ,  107  as represented in  FIG. 14  is the production position, i.e. the position in which the printing unit prints. In the course of coming into this production position, the three frame elements  104 ,  106 ,  107  are connected with each other by the use of a locking device  108 . Six such locking devices  108  are represented in  FIG. 14 . 
   In the depicted preferred embodiment, the center frame element  106  has at least two pairs of cylinders arranged as a bridge printing group, but preferably has four bridge printing groups which are arranged to work together vertically. 
   The forme cylinders of the several disclosed preferred embodiments preferably have at least two printing plates in the axial direction, and preferably have four printing plates. 
   While preferred embodiments of movable frame parts in a printing press, in accordance with the present invention, have been fully and completely described hereinabove, it will be apparent to one of skill in the art that various changes in, for example, the drive motors for the various cylinders and rollers, the type of material web being printed, and the like could be made without departing from the true spirit and scope of the subject invention which is to be limited only by the appended claims.