Abstract:
A device for conveying and depositing paper on at least one stack, with a device ( 27 ) for moving conveyor rollers ( 1 ) laterally in the conveying direction of the sheets and a device ( 28 ) for transmitting rotations to conveyor rollers ( 1 ), in particular to operate within a depositing device of a sheet-processing machine. In order to ensure a quicker lateral movement of conveyor rollers ( 1 ) and to protect the devices ( 27 ) and ( 28 ) from soiling and mechanical effects, members of the same are located within a rod ( 2 ), on which conveyor rollers ( 1 ) are located. Furthermore, there are possibilities to calibrate the device with respect to the position of conveyor rollers ( 1 ) and to adjust height differences within a stack with tensionless equalization.

Description:
FIELD OF THE INVENTION  
         [0001]    The invention relates to a device for conveying and depositing sheets on at least one stack, with a device for moving the conveyor roller laterally in the conveying direction of the sheets and equipment for the transfer of rotation to the conveyor roller, in particular for operating within a depositing device of a machine for processing sheets, in particular a digital multicolor printing press.  
         BACKGROUND OF THE INVENTION  
         [0002]    In paper processing machines, in particular in multicolored printing presses, subassemblies are used at the end of the paper path as an extension arm that controls the depositing paper sheets on an already existing stack or which can build a new stack. To this end, there are systems, for example, that work with negative pressure and overpressure, or which operate, in a purely mechanical way, e.g., by tappets and holding down systems with rollers located above. Such mechanical systems, as describe in the publication of disclosure of patent DE 199 57 574 A1, make it possible to deposit sheets with a very high degree of precision. Fewer material-intensive members are used than with customary extension arms, whereby sufficient space is available in the area around the stack to remove the stack, to inspect it or to further process the sheets.  
           [0003]    In the extension arm described in the patent DE 199 57 574 A1, a last pair of rollers in the paper path in particular is used as a conveyor roller pair, which is attached above a pair of tappets and a hold down device. The function of this conveyor roller pair is used in conjunction with the pair of tappets and the holding down device to deposit sheets conveyed in the area of the extension arm that fit perfectly on a paper stack or to build a new stack.  
           [0004]    The transport roller pair can be moved by rotation and can be laterally moved in the conveying direction of the sheet. The surface of the conveyor roller has a very high friction value, while the tappets located directly below the conveyor rollers on their side facing the rollers have a very low friction value. The lateral mobility of the conveyor rollers makes it possible to correct any misalignment of a sheet, at least in its position transverse to the conveying direction. Furthermore, the lateral position of sheets on a stack can be controlled, so that, for example, offsets for differentiating between the various printing jobs within the stack can be produced.  
           [0005]    The sheets are quickly conveyed to the stack by rotating rollers. The transfer of the rotation to the conveying rollers takes place by a drive shaft. The rollers are attached to an aluminum pipe that is connected to the drive shaft. The drive shaft can then be driven by a toothed belt.  
           [0006]    For the lateral movement of the conveyor roller in DE 199 57 574 A1, an actuator is provided above the conveyor rollers, which drives a spindle. In order to prevent twisting, a swivel head is fastened to a spindle, which drives a rod. The rod is screwed into a non-rotating adjusting ring on the aluminum pipe of the conveyor rollers. The adjusting ring is transversely coupled to the conveyor rollers, which makes it possible to move the conveyor rollers laterally.  
           [0007]    The rod drives the swivel head on the spindle by an opening. When a new piece of paper is to be deposited on the stack, it is necessary that the conveyor rollers be removed from the surface of the stack, for which lever arms are provided on the drive shaft.  
           [0008]    The speed with which the conveyor rollers can be laterally moved is limited here. It can be increased, for example, via a spindle that has a larger spindle stroke. However, such an extension of the system would entail substantial cost increases.  
           [0009]    The spindle, which effects the lateral movement of the conveyor rollers, is shown here open and unprotected. As a result, it is easily soiled, and it is also susceptible to mechanical effects. Consequently, it may be damaged or at least its function may be impaired.  
           [0010]    The drive shaft for transferring the rotation to the conveyor rollers may be driven by means of a toothed belt. Since there may be a difference in height between the sides of the sheet stack, a tilt of the drive shaft may also be required via the conveyor rollers. This tilt may amount to 4°. Since the wheels of the tooth belt are rigidly connected with the drive shaft, this tilt is also transmitted to the flanged rim pulleys of the toothed belt wheels. As a result, the toothed belts are pushed to the edge of the flanged rim pulleys and are constantly rubbed by the tilting position. Due to the wear and tear of the toothed belt, they have to be changed often.  
         SUMMARY OF THE INVENTION  
         [0011]    The basic task of the invention is to cost effectively raise the speed with which the conveyor rollers are laterally moved in the conveying direction of the sheets. In addition, a protection of the spindle against soiling and external, undesired mechanical effects and/or damages is also achieved. Furthermore, the intervals in which the toothed belt wheels have to be changed due to wear and tear is extended.  
           [0012]    The task is solved according to the invention, whereby members of the device for the lateral movement of the conveyor rollers and members of the device for the transfer of rotation are located in a pipe to which the conveyor rollers are attached.  
           [0013]    The conveyor rollers are securely attached to a rod, according to the invention. This rod is connected with two lever arms in such a way that the rod can rotate freely and can be moved laterally. The rod with the conveyor rollers can be vertically lifted by the lever arms, which is necessary when adding new sheets to the stack. The advantage of this arrangement is that the rod within the holder can rotate, since the latter is not hindered by the lever arms. As a result, lateral movements of the rod and thus of the conveyor rollers are possible that are not impaired by the holder. Since the conveyor rollers in this embodiment of the invention are directly connected with the rod, they can also be lifted vertically, without another member having to be connected between them.  
           [0014]    According to the invention, the device is such that members for the transfer of the rotation to the conveyor rollers are located within the rod. They contain a drive shaft, which is arranged on the side of the rod and which is form-fitted with the rod. The drive shaft can be driven with the coupled rod and it can be moved rotationally, so that, in addition, a torque can be transmitted to the conveyor rollers. In this manner, the driving mechanism of the conveyor rollers is located compactly within the rod. In addition, it is not necessary for the drive shaft to have the entire width of the extension arm. The production of the extension arm thus requires less material. Furthermore, the other end of the rod remains free, so that members for other devices can be fitted here. It is also possible that each conveyor roller be individually driven by separate drive shafts. As a result, it can be guaranteed that the conveyor rollers can rotate at different speeds. Different rotational speeds of the rollers can be used advantageously to correct the position of the sheets. If the drive shaft does not pass through between the two conveyor rollers, the rotating axes of the rollers can also adopt different angles to each other, but they must not run parallel to each other. Other correcting possibilities for the sheet position are thus provided. The sheets can also be accessed more easily from the top, since a limiting member is omitted. Furthermore, sources of error are omitted, since fewer wear and tear parts are involved in the transmission of rotation. Since the drive shaft now lies completely within the rod, it is no longer exposed to soiling and potential sources of malfunction.  
           [0015]    Advantageously, it is further provided according to the invention, that the drive shaft not be directly connected with the rod. A carrier is provided for this purpose, whose connection is perfectly fitted with the drive shaft and the rod. The carrier can be freely moved on the drive shaft and/or the inside of the rod. For this purpose, both the drive shaft as well as the inside of the rod have a suitably adjusted shape.  
           [0016]    The carrier can be adjusted or press-fitted into the rod or into the drive in such a way that, with regard to an interconnecting point between the drive shaft and rod, it can no longer be moved horizontally; as a result, friction points can advantageously be avoided and the stability of the system consisting of a drive shaft, carrier and rod, increases. First, the horizontally freedom of movement of the carrier on at least one of the surfaces, inside the rod or the top surface of the drive shaft, is guaranteed, so that the rod can be laterally moved. Only in this fashion can the rollers also be laterally adjusted for positioning of the sheets. The drive shaft transmits the rotation to the conveyor rollers via the carrier; the most favorable condition for this is when one side of the carrier is anchored. According to the invention, it is thus envisaged to anchor the carrier to the inside of the rod. The carrier is connected with the drive shaft for rotation and disconnected for later movements.  
           [0017]    In accordance with the device, the task of the invention is further solved in such a way that the members of the device for lateral movement of the conveyor rollers are located inside the rod. It is thus provided that in the other end of the rod opposite the device for the transmission of rotation, there is a spindle with a ball screw nut attached to it. The ball screw nut is connected with the rod in such a way that it is completely disconnected for rotation. To this end, in accordance with the device, a connection between the ball screw nut and rod in the form of bearings is provided. Furthermore, the ball screw nut is coupled to the rod for lateral movements. According to the invention, these couplings can take place via the bearings, which provide a rotational disconnection of the ball screw nut from the rod. It is provided that the ball screw nut can be connected perfectly form-fitted with the bearings, so that lateral movements of the ball screw nut can be directly transmitted to the bearings and thus to the rod as well. In this manner, a considerably precise control of the conveyor rollers can thus take place, since with the perfectly fitted attachment of the ball screw nut provided here, it can thus be attached between two bearings, so that practically no more play exists. In this embodiment of the invention, the spindle lies inside the rod and it is thus protected from soiling and mechanical loads. As a result, fewer damages and malfunctions of the spindle occur. Since the spindle here effects the lateral movement of the rod, a higher speed of the lateral movement can easily be reached via an increased r.p.m. Here, no additional members are involved in the transmission of movement, which would malfunction under an increased speed, and even the drive itself is not a limiting member here.  
           [0018]    Advantageously, it is provided in the invention that the lever arms are connected with the rod via swivel heads. Preferably, the swivel heads should be located in the area around the end of the rod. In this way, it is possible to disconnect the lever arms by tipping the rod. Tipping thus always occurs when the stack has a difference in height between various points of its surface. The conveyor rollers lie temporarily on the stack during the sheet depositing process. In this way, its tilting is directly transmitted to the rod. Since the lever arms are disconnected via the swivel heads from the rod during the tilting, favorably fewer shear forces are exerted on the lever arms.  
           [0019]    According to the invention, it is provided that both the drive shaft, as well as the spindle, are connected with drive members via cardan joints. These cardan joints should advantageously be concentric to the swivel heads on the axis of the rod. In this way, it is ensured that the tilting of the conveyor rollers is not transmitted to the lever arms or to the drive members, the drive shaft and the spindle. The drive members should be connected with the lever arms via bearings; there should be no direct connection with the rod. The drive members should be either rotational via the drive shafts and bearings, or disconnected from the rod for lateral movements. According to the invention, toothed belts can be provided, which transmit the force to the drive members in the form of toothed belt wheels. The tooth belt wheels are provided with flanged rim pulleys, which the toothed belts surround laterally. By tipping the toothed belt wheels relative to the toothed belts, the toothed belts run down the flanged rim pulleys and are thus worn out.  
           [0020]    This tipping can thus be avoided by the cardan joints and, as a result, the service life of the toothed belts can be extended. The same also applies for other driving systems, such as geared wheels.  
           [0021]    In a further expansion of the invented device, at least one position-locating unit, to identify the position of the rod, in particular the position of the conveyor rollers, at least one side of the rod is provided. It can be provided in the area surrounding a swivel head, preferably on a lever arm. The position-locating unit can preferably include a fork light barrier on the lever arm and a disk, which is located on the rod. This position-locating unit can fulfill two functions. It can prevent the rod from being moved so far that a swivel head, a drive member or other members of the device within the toothed belt wheel are damaged or destroyed. The disk is anchored in a fixed position on the rod. This position is chosen so that the disk then immediately releases the fork light barrier if the lateral movement of the rod exceeds a maximum. In accordance with the device, two position-locating units are provided at each end of the rod.  
           [0022]    In a second embodiment, the position-locating unit can be used to calibrate the position of the conveyor rollers. In this case, only a position-locating unit is required. Since the distance of the disk to the rod of the conveyor rollers is constant and known, by detecting the position of the disk, the position of the conveyor rollers can be directly concluded. This is advantageous in order to ensure the highest depositing of the sheets on the stack. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0023]    Embodiments, which are able to provide further characteristics of the invention, but to which the invention is not limited in scope, are illustrated in the drawings in which:  
         [0024]    [0024]FIG. 1 is a device, according to the invention, for conveying and depositing sheets on a stack;  
         [0025]    [0025]FIG. 2 shows the construction of a device according to FIG. 1 for conveying and depositing of sheets on a stack;  
         [0026]    [0026]FIG. 3 is a device for the lateral movement of conveyor rollers;  
         [0027]    [0027]FIG. 4 is a device for the transmission of rotation to conveyor rollers;  
         [0028]    [0028]FIG. 5 shows a connection between a driving member with members of the device for the lateral movement of conveyor rollers according to FIG. 3; and  
         [0029]    [0029]FIG. 6 is a position-locating unit. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0030]    [0030]FIG. 1 shows a top view of a device for the conveying and depositing of sheets on a stack. Conveyor rollers  1  are securely anchored to a rod  2 . This rod is supported by two swivel heads  3  on lever arms  4 . Lever arms  4  are connected rotationally with a partially illustrated housing via pivot points  5 . Toothed wheels  6  and  7  are located on the ends of rod  2 . A position-locating unit is illustrated, which consists of a fork light barrier  19  surrounding lever arms  4  and two disks  20  at the end of rod  2 .  
         [0031]    [0031]FIG. 2 shows a longitudinal section through the device illustrated in FIG. 1 for conveying and depositing sheets on a stack. The conveyor rollers  1  are located on rod  2  in such a way that they form a right angle. The ends of rod  2  hold a device  27  for lateral movement and a device  28  for transmitting a rotation to the conveyor rollers  1 .  
         [0032]    [0032]FIG. 3 illustrates an enlargement of Area A in FIG. 2, in which a device  27  for the lateral movement of conveyor rollers  1  is illustrated. Rod  2  is supported by a swivel head  3  on lever arm  4 . Lever arm  4  is connected by means of a ball bearing  9  with toothed belt wheel  6  via a sleeve  10 . The toothed belt wheel  6  has flanged rim pulleys  8  (not shown) for guiding toothed belts provided for driving. Via the toothed belt wheel  6 , a rotation can be transmitted to a drive shaft  11 , which is connected with a spindle  13  by a cardan joint  12 . The center point of the cardan joint coincides with the center point of the swivel head  3 . On spindle  13 , a ball screw nut  14  is positioned, which is disconnected by a ball bearing  15  of rod  2  during rotations. The ball screw nut  14  is connected to a sleeve  16 , which encloses spindle  13 , cardan joint  12  and drive shaft  11 . This sleeve  16  is supported inside rod  2  on a sleeve bearing  17  that has been press-fitted into rod  2  and is thus disconnected from rod  2  rotationally. Rod  2  terminates with the sliding bearing and does not surround the entire sleeve  16 . At the end of sleeve  16 , there is a clamping block  18 , which has a wrench opening across flats and which, in addition, is secured to sleeve  10  so that it cannot twist. Free spaces  29  and  30  for the clamping block and sleeve  16  are recessed within sleeve  10 . Furthermore, positioned on lever arm  4  is a fork light barrier  19 , which can be released by the disk  20  on rod  2 .  
         [0033]    [0033]FIG. 4 shows an enlargement of Area B in FIG. 2. Members of the device  28  for the transmission of rotation to conveyor rollers  1  are illustrated therein. The toothed belt wheel  7  is also supported herein by a ball bearing  21  on a sleeve  22 . This sleeve  22  is connected with lever arm  4 . Flanged rim pulleys  8  are also located on this toothed belt wheel  7  for guiding toothed belts that are not shown. Via the toothed belt wheel  7 , a drive shaft  23  is driven, which is connected via a cardan joint  24  with a drive shaft  25 . The center of the flanged rim pulley coincides with the center point of swivel head  3 , which is connected with lever arm  4 . The drive shaft is connected with the lever arm via a carrier  26 . Rod  2  has a corresponding fit, so that the carrier  26  is connected with rod  2  so that it cannot twist. The carrier  26  is thus connected with rod  2  via a wrench opening across flats. Free spaces  31  and  32  for rod  2  are recessed within sleeve  22 . On lever arm  4 , a fork light barrier  19  is positioned, which, with a disk  20 , which is attached to rod  2 , can verify the position of rod  2 .  
         [0034]    [0034]FIG. 5 shows a cross-section of the toothed belt wheel  6 , in which the members of the device  27  for lateral movement of conveyor rollers  1  can be seen. Clamping block  18  is attached to the sleeve  16 , through whose axis drive shaft  11  is located. The clamping block  18  is configured as a dihedron, and sleeve  10  has a corresponding shape, so that a movement of the clamping block  18  is only possible in the direction of the free space  30 . It is not possible to turn clamping block  18 . As a result, the spindle connected with clamping block  18  via ball screw nut  15  and sleeve  16  is secured against twisting or rotating.  
         [0035]    [0035]FIG. 6 illustrates a top view of the tilted top at the end of rod  2 , so that a position-locating unit can be seen. The fork light barrier  19  is securely mounted on lever arm  4 . The shape of the disk, which is located on rod  2 , is configured in such a way that from a certain position of rod  2 , an outer rim of disk  20  is inserted into the opening  33  of fork light barrier  19 .  
         [0036]    With the configuration, as shown in FIG. 1, sheets can be deposited on a stack. Conveyor rollers  1  turn together with rod  2  around a common axis. The sheets can be conveyed in this manner, since the surfaces of conveyor rollers  1  have a high friction value. The transmission of the rotation to rod  2  takes place via the toothed belt wheel  7 . In order to convey a sheet in the conveying direction, the sheet lies on the surface of the stack, whereby tappets (not shown) are located between sheets and stack. Conveyor rollers  1  lie thereby on the sheet. For the tappets to be removed, conveyor rollers  1  must be lifted. To this end, rod  2  is lifted by lever arms  4 . The lever arms  4  are therefore connected with pivot points  5  with a housing (not shown) and can thus be vertically lifted. In this position, the sheet, supported by a holding down system (also not shown) is anchored to the stack. In order to convey a new sheet to the stack, conveyor rollers  1  are lowered on the new sheet in such a way that the sheet is set between conveyor rollers  1  and the stack. If the lateral position of the sheet is not that desired, which may also be the case, for example, if distance is created within the stack, there is thus the possibility that conveyor rollers  1  can laterally move the sheet, so that the desired position is taken. For this purpose, it is possible, according to the configuration of the invention shown, to move rod  2  laterally between the two lever arms  4 . The device  27 , configured for laterally moving rod  2 , is driven by the toothed belt wheel  6 .  
         [0037]    In order to ensure an exact lateral movement of a sheet and to pile up a stack in a desired position perpendicular to the sheet conveying device, the absolute position of conveyor rollers  1  must be determined. To this end, a position-locating unit, consisting of a fork light barrier  19  and a disk  20 , which is anchored to rod  2 , is located at the end of rod  2 . Before the sheet can be conveyed, the absolute position of the conveyor rollers is determined via this position-locating unit and device  27  for lateral movements of the conveyor rollers  1  is calibrated with this unit. For this purpose, rod  2  is laterally moved so far, that the outer rim of disk  20  is driven through the fork light barrier  19 . As a result, a signal is given, so that the position of disk  20  is now known. Since the distance between conveyor rollers  1  and disk  20  cannot be changed, the result is that now the position of conveyor rollers  1  can be precisely determined. This knowledge can be used by control electronics, which is not shown here, to deposit the sheet as targeted and precisely lateral to its conveying direction.  
         [0038]    A second position-locating unit, consisting of a fork light barrier  19  and a disk  2 , is also located on rod  2 . This unit, in cooperation with the first position-locating unit, is used to prevent rod  2  from being moved too far, which would lead to a destruction of members within a toothed belt wheel  6  or  7  or which would lead to the lateral movement of conveyor rollers  1  or to the transmission of rotation to the conveyor rollers  1  by members of one of the devices  27  or  28 . Since rod  2  is inserted up to the toothed belt wheels  6  and  7 , a lateral movement of rod  2  beyond a maximum must be avoided. Disks  20  are thus located in positions in rod  2  that are measured in such a way that the respective outer rims of the disks release the fork light barrier  19 , if the lateral movement of rod  2  just reaches this maximum.  
         [0039]    The lateral movement and the transmission of rotation can be ensured with the members of the device shown in FIG. 2. Both device  27  for lateral movement of conveyor rollers  1  as well as device  28  for the transmission of rotation lie within rod  2 . The conveyor rollers  1  are thereby located in rod  2 , which is moved by devices  27  and  28 . As a result, the members of devices  27  and  28  that are located within rod  2  are protected from soiling and external effects. The lever arms  4  are connected with rod via swivel heads  3 . As a result, rod  2  can freely rotate and it is laterally moved, as explained above, without being impaired by the position.  
         [0040]    The members of the device  27  for lateral movement of the conveyor rollers  1  shown in FIG. 3 ensure that conveyor rollers  1  can be positioned in such a way that the paper conveyed can be deposited on a stack as desired. The conveyor rollers  1  lie on rod  2 . The lateral movement is transmitted to rod  2  by a ball screw nut  14 . To this end, the ball screw nut  14  is connected with rod  2  via the bearings  15  and  17 , whereby the connection with bearing  17  takes place via a sleeve  16  that is attached to the ball screw nut  14 . The system composed of ball screw nut  14  and sleeve  16  is so firmly fitted in the space between bearings  17  and  16 , that lateral movements of the ball screw nut  14  are directly transmitted to rod  2 . Bearing  15  hereby takes the form of a ball bearing and bearing  17  takes the form of a sliding bearing. As result, rod  2  can rotate, without entraining ball screw nut  14 . The sleeve  16  is screwed onto ball screw nut  14  in this configuration and is used for the axial anchoring of ball screw nut  14  inside rod  2 . On the other hand, it is also possible via both bearings  15  and  17  to better transmit the lateral movement in both directions via both bearings  15  and  17 , since one bearing  15  lies at the beginning of ball screw nut  14  and the other bearing  17  is attached to the end of sleeve  16 . Sleeve  16  is thus adjusted at this end to the shape of bearing  17 . Bearing  17  is firmly inserted in rod  2 .  
         [0041]    The lateral movement of ball screw nut  14  takes place herein via spindle  13 . Spindle  13  is rotated via cardan joint  12  and drive shaft  11 . The transmission of the rotation takes place externally by the toothed belt wheel  6 , which is driven by a toothed belt (not shown in greater detail), which should lie between the flanged rim pulleys. In this manner, a lateral movement of rod  2  can be achieved by an external actuation via a toothed belt.  
         [0042]    For further anchoring of ball screw nut  14  and sleeve  16 , a clamping block  18  is attached to the end of sleeve  16 . This clamping block  18  has a wrench opening across flats, as illustrated in FIG. 5. It is more precisely configured as a dihedron. This clamping block  18  is fitted into sleeve  10 , so that no lateral movement of sleeve  16  is possible. Sleeve  10  is used herein to connect the toothed belt wheel  6  to lever arm  4  via a ball bearing  9 . In order that rod  2  can be moved laterally at least up to a maximum, an empty space  29  inside the toothed belt wheel  6  is provided. In order that rod  2  can also be vertically tipped, without this tipping being transmitted to the toothed belt wheel  6 , rod  2  is connected with lever arm  4  with a swivel head  3 . There is no direct connection between clamping block  18  and the toothed belt wheel  6 . In order to prevent movements between clamping block  18  and sleeve  10 , when rod  2  is vertically tipped, a space  30  is envisaged above sleeve  16  and clamping block  18 . This makes it possible for rod  2  to be tipped up to a maximum angle provided by an empty space  30 , without clamping block  18  or sleeve  16  inside sleeve  10  being aware of it.  
         [0043]    It can be seen that the functionality of device  28  for the transmission of rotation to conveyor rollers  1  in FIG. 4 is analogous to FIG. 3. The device is driven by a toothed belt, which runs on the toothed belt wheel  7 . The toothed belt is located herein between the flanged rim pulleys  8 . The toothed belt wheel  7  lies above the ball bearing  21  on a sleeve  22 , which makes the connection with the lever arm  4 . The torque is transmitted by the toothed belt wheel  7  to a drive shaft  23 . The transmission to the drive shaft  25  then takes place further via a cardan joint  24 . The entire drive shaft, including drive shaft  23  to  26 , is surrounded by rod  2 . The connection of rod  2  with lever arm  4  takes place on this side of rod  2  via a swivel head  3 . The cardan joint is located thereby concentrically within swivel head  3 . Rod  2  may be tipped by the difference in height of the stack as a result of conveyor rollers  1 , which causes a change in the angle of rod  2  with respect to lever arm  4 . Since rod  2  is not directly connected to the toothed belt wheel  7 , the slanting is not transmitted to the toothed belt wheel  7 . The toothed belt wheel  7  is thus always parallel to lever arm  4  and thus aligned with the running direction of the toothed belt. As a result, increased wear and tear of the toothed belt does not occur, since the latter does not run on the flanged rim pulleys  8 , which would otherwise be the case.  
         [0044]    Drive shaft  25  has a wrench opening across flats, which is synchronized on a carrier  26 . This carrier  26  thus can not be twisted with regard to drive shaft  25 , but it can be freely moved laterally on drive shaft  25 . On the other hand, the carrier  26  is also connected with rod  2 , which has a corresponding fit, in such a way that it cannot be twisted. The carrier  26  cannot be freely moved with regard to rod  2 , and thus transfers a rotating movement of drive shaft  25  directly to rod  2 . On the other hand rod  2  can also be moved freely laterally, without this movement being transferred to drive shaft  25 , since carrier  26  can slide freely in this direction on drive shaft  25 . Also, in order to prevent the lateral movement of rod  2  from damaging any members inside the toothed belt wheel  7 , an empty space  31  in the longitudinal direction within sleeve  22  is provided. Another empty space  32  is located above rod  2  within toothed belt wheel  7  between rod  2  and sleeve  22 , so that rod  2  can also tip without doing any damage. In this way, conveyor rollers  1  can be laterally moved and adjusted to the difference in height of the stack, without damaging toothed belt wheel  7  and without heavy wear and tear on the toothed belt.  
         [0045]    Another protection from the lateral movement of rod  2  and for calibration of the lateral movement of conveyor rollers  1  is provided by the position-locating unit, including fork light barrier  19  and disk  20 . The exact functionality has already been explained with regard to FIG. 1.  
         [0046]    [0046]FIG. 5 shows how the members of device  27  for lateral movement of conveyor rollers  1  are fitted inside sleeve  10 , so that they cannot twist. Drive shaft  11  is located inside sleeve  16 . There is an empty space  30  between sleeve  16  and drive shaft  11  that is sufficient, that sleeve  16  in relation to drive shaft  11  with respect to a slanting of rod  2  can be sufficiently tipped. Sleeve  16  is directly connected with ball screw nut  14  and is stabilized via clamping block  18  within sleeve  10  and thus is stabilized in toothed belt wheel  6 . Clamping block  18  is thus configured as a dihedron, whereby sleeve  10  surrounding it also has a corresponding shape. Furthermore, an empty space  30  between clamping block  18  and sleeve  10  is available so that clamping block  18  within sleeve  10  can tip in correlation to the position of conveyor rollers  1 . The empty space  30  is configured in such a way that rod  2 , which has already been connected with clamping block  18  via sleeve  16 , can only be tipped at one level.  
         [0047]    It can be seen more precisely in FIG. 6 how the position-locating unit functions. Disk  20  is directly connected with rod  2 . A lateral movement of rod  2  thus has a direct effect on disk  2 , whose rim is inserted with a certain movement in the opening  33  of fork light barrier  19 . The position of disk  20  can thus be detected. Since the distance between disk  20  and conveyor rollers  1  is determined, in exactly the same way, the position of the ends (not shown) of rod  2  within the toothed belt wheels  6  and  7  can be determined. This information can thus be further used to calibrate the position of the conveyor rollers  1 , or another lateral movement of conveyor rollers  1  can be prevented from exceeding a maximum, which would cause damage within toothed belt wheels  6  and  7  by rod  2 .  
         [0048]    The invention has been described in detail with particular reference to certain preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.