EP0004264B1 - Sheet delivery device in printing machines - Google Patents

Description

The invention relates to a sheet delivery device on printing presses with pneumatic braking devices on the chain delivery, which are arranged as rotating brake rollers acted upon by suction air on a carrier shaft running below the chain conveyor transversely to the sheet conveying direction in front of the delivery stack for braking and tightening the incoming sheets.

In sheet delivery devices with braking devices of this type, the braking effect on the end of the outgoing and to be deposited sheet is achieved by a lower peripheral speed of the suction brake rollers compared to the higher rotating speed of the chain grippers, which corresponds to the sheet speed. The difference in speed between the suction brake rollers and the bow also tightens them. As soon as the front edge of the sheet is released by the chain grippers, the suction brake rollers exert a braking effect on the rear end of the sheet and slow it down until it leaves the rear edge of the suction brake roller in such a way that the tightened sheet is placed on the delivery stack at approximately the circumferential speed of the suction brake rollers.

Particularly in the case of perfecting and reverse printing work, the freshly printed underside of the sheet can be smeared on the suction brake rollers by a correspondingly high differential speed between the suction brake rollers and the sheet, which is why there is a need to employ the same only in pressure-free sheet areas.

Braking devices are now known which take into account the circumstances described above to the extent that their suction brake rollers are laterally adjustable on pressure-free arc points. In practice, however, there is the difficulty that, particularly in the case of perfecting and reverse printing work, there are often only extremely narrow, pressure-free areas within the printed image, so that wide suction rolls, i.e. those with a wide sheet support surface can no longer be used.

DE-OS 26 27 812 shows such a braking device in which the suction brake rollers can be laterally adjusted to pressure-free arc points. However, since the sheet contact surfaces of the suction brake rollers are relatively wide, there is a danger if the distance between two correspondingly wide, pressure-free areas within the printed image is very large, that the sheets tend to sag, particularly with lighter paper qualities. In order to prevent this shortcoming, spur wheels have been provided between the suction wheels on support disks, which additionally support the bow.

This device has the disadvantage that under certain circumstances a uniform deceleration of the sheet over its entire width is not guaranteed. Furthermore, this device does not take into account the possibility that only narrow, pressure-free areas are present within the printed image. In such cases, it is also unsuitable and cannot be used.

Another possibility to remedy the situation mentioned at the outset is to equip the braking devices with suction brake rollers, which have a narrow sheet support surface with a width of, for example, 2 to 3 mm, and with which the problems mentioned above can be remedied. Such suction brake rollers with a narrow sheet support surface are now again limited in terms of their suction or braking force, which can only be overcome with a disproportionate amount of effort, since their suction effect on heavy papers, for example over 130 g / m ² , and not at maximum speed sufficient to delay the bends sufficiently to the desired extent.

So there is the possibility, when assembling the machine, either to arrange suction brake rollers with a wide suction or sheet support surface in the braking devices and thus achieve a good braking effect, or to provide those with a narrow suction or sheet support surface and thereby when processing thicker papers or Carton forced to accept an insufficient braking effect. An increase in the braking force due to an increase in the vacuum is only possible to a limited extent for manufacturing reasons and in terms of expenditure, both in terms of means and costs.

Based on this prior art, the invention has for its object to provide a sheet delivery device with pneumatic braking devices that allows an adaptation of their braking force to the type of paper to be processed to achieve an optimal braking effect on the sheets to be deposited in a short time and with simple means.

This object is achieved according to the invention with a sheet delivery device of the type mentioned in the introduction in that the braking devices are interchangeable with those with a differently shaped sheet supporting surface. With this arrangement, a change in the pressure-free zones in the printed image and the choice of a different paper type can be taken into account immediately, by the possibility of an extremely rapid change of the braking devices with little effort.

In an advantageous embodiment of the invention, the carrier shaft is formed in one piece, on which the braking devices are arranged so as to be removable and attachable. This problem-free design ensures easy handling of the braking devices, since only a few simple steps are required to replace them.

A further development of the concept of the invention, which is particularly suitable for the use of almost all customary and known suction rolls, is extremely inexpensive to manufacture due to the low outlay in terms of the design means and also guarantees the shortest replacement times, the carrier shaft is designed in several parts and can be separated, on which the braking devices can be removed are.

To further simplify and save time when replacing the brake rollers, the brake devices are designed in one piece as brake rollers with built-in suction chambers and integrated suction air supply, the brake rollers being driven by separate drive wheels.

Further advantageous refinements of the inventive concept are contained in the following description and in subclaims 4 to 7 and 10 to 15.

The invention is explained in more detail below in the form of a basic embodiment and four exemplary embodiments with reference to the drawings.

• Fig. 1 eine schematische teilgeschnittene Draufsicht einer Grundausführung einteiliger Bremsvorrichtungen mit einteiliger Trägerwelle und separatem Antrieb,
• Fig. 2 eine Seitenansicht der einteiligen Bremsvorrichtungen mit separatem Antrieb,
• Fig. 3 eine teilgeschnittene Draufsicht von Figur 2,
• Fig. 4 eine teilgeschnittene schematische Draufsicht einer ersten Ausführungsform der zweiteiligen Bremsvorrichtungen mit mehrteiliger, bedienungsseitig trennbarer Trägerwelle und Bremswalzer) mit schmaler Bogentragfläche,
• Fig. 5 eine teilgeschnittene Seitenansicht der zweiteiligen Bremsvorrichtungen mit separater Traverse,
• Fig. 6 eine teilgeschnittene schematische Vorderansicht einer zweiten Ausführungsform der zweiteiligen Bremsvorrichtungen mit mehrteiliger, antriebsseitig auskuppelbarer Trägerwelle mit Bremswalzen mit schmaler Bogentragfläche,
• Fig. 7 eine teilgeschnittene schematische Draufsicht einer dritten Ausführungsform der zweiteiligen Bremsvorrichtungen mit mehrteiliger, beidseitig auskuppelbarer Trägerwelle und Bremswalzen mit breiter Bogentragfläche und
• Fig. 8 eine schematische teilgeschnittene Vorderansicht einer vierten Ausführungsform der zweiteiligen Bremsvorrichtungen mit mehrteiliger, antriebsseitig ausgekuppelter und bedienungsseitig abgeschwenkter Trägerwelle mit Bremswalzen mit breiter Bogentragfläche.

It shows:

• 1 is a schematic partially sectioned top view of a basic design of one-piece braking devices with one-piece carrier shaft and separate drive,
• 2 is a side view of the one-piece braking devices with a separate drive,
• 3 is a partially sectioned top view of FIG. 2,
• 4 shows a partially sectioned schematic top view of a first embodiment of the two-part braking devices with a multi-part carrier shaft that can be separated on the operator side and a brake roller) with a narrow curved support surface,
• 5 is a partially sectioned side view of the two-part braking devices with a separate traverse,
• 6 is a partially sectioned schematic front view of a second embodiment of the two-part braking devices with a multi-part carrier shaft that can be disengaged on the drive side with brake rollers with a narrow curved support surface,
• Fig. 7 is a partially sectioned schematic plan view of a third embodiment of the two-part brake devices with multi-part, on both sides disengageable carrier shaft and brake rollers with a wide sheet bearing surface and
• Fig. 8 is a schematic partially sectioned front view of a fourth embodiment of the two-part braking devices with multi-part, disengaged on the drive side and swung down on the operator side carrier shaft with brake rollers with a wide sheet bearing surface.

As shown in FIG. 1, in a basic embodiment of the invention, a one-piece carrier shaft 4 is fastened in front of the delivery stack 1 of a sheet boom in the side walls 2 and 3 of a suction roller carriage. On the one-piece carrier shaft 4, individual removable and attachable one-piece braking devices 5 are slidably arranged at arbitrary intervals, which can be locked by means of clamping screws 6.

Offset to the one-piece carrier shaft 4, below and seen in the sheet running direction in front of the same, a drive shaft 7 is mounted in the side walls 2 and 3, which is driven by a motor 8 flange-mounted on the outside of the side wall 3. On the drive shaft 7, in the spaces between the one-piece braking devices 5 corresponding distances, these opposing drive wheels 9 are arranged. The drive wheels 9 are fixed only in the circumferential direction and are guided in the axial direction by the one-piece braking devices 5.

According to FIGS. 2 and 3, a one-piece braking device 5 consists of a holder 12, the rear end of which is formed approximately as a semicircular bearing shell 13, which can be plugged onto the one-piece carrier shaft 4. The previously mentioned clamping screw 6, which is inserted at the end into the bearing shell 13, is used to lock the holder 12. At the front end of the holder 12, a suction air chamber sleeve 14 is fastened, on which a brake roller 16 is mounted by means of ball bearings 15. Continuous suction chambers 17 are incorporated into the brake roller 16 except for the outer surface of the suction air chamber sleeve 14, so that the brake roller 16 has the shape of a step. In addition, the brake roller 16 is provided on both sides with two drive grooves 18.

On the circumferential part of the suction air chamber sleeve 14 facing the upper side of the holder 12 and thus the sheet 10 to be braked, an inner air intake opening 19 is congruent with the brake roller 16 mounted on it. Likewise, the free end of the suction air chamber sleeve 14 is provided on the circumference with an outer air inlet opening 20 which coincides with the suction air duct of a suction air supply 21, which is attached to an air inlet sleeve 22. The air inlet sleeve 22 is plugged onto the free end of the suction air chamber sleeve 14 and can be fixed by means of a threaded pin 23.

On the drive shaft 7, the drive wheels 9, in a number corresponding to the holders 12, are arranged displaceably in a longitudinal groove 24 and fixed in the circumferential direction by means of driving screws 25.

The drive wheels 9 are provided on both sides with drive grooves 26 that drive grooves 18 of the brake rollers 16 face flush. Drive belts 27 circulate in the drive grooves 26 and span the brake rollers 16 in the drive grooves 18. As drive belts 27 preferably those with a circular cross section are used. However, it is within the scope of the invention to use other types of belts, for example with flat or trapezoidal profiles. Of course, the brake rollers 16 can also be driven via toothed belts and toothed belt pulleys.

As shown in Figures 2 and 3, the drive wheels 9 are equipped on one side with a guide groove 28 which is delimited by a lateral support collar 29. The clamped on the one-piece carrier shaft 4 holder 12 lie with a semi-circular support shoulder 30 incorporated into it in the guide groove 28 and thereby secure the drive wheels 9 against unwanted axial displacement.

Instead of using drive belts 27, the drive wheels 9 can be provided with teeth, the circumferential teeth of which engage in the suction chambers 17 of the brake rollers 16 and thereby drive the same.

• Die Antriebsräder 9 der vom Motor 8 angetriebenen Antriebswelle 7 übertragen ihre Rotationsbewegung entweder mittels der Antriebsriemen 27 oder der Verzahnung auf die Bremswalzen 16. Dabei wird die Saugluft des nicht dargestellten Vakuumerzeugers über den Saugluftkanal der Saugluftzuführungen 21 durch die äußere Lufteinlaßöffnung 20 in die Saugluftkammerhülse 14 eingeleitet und gelangt von dort über die innere Lufteinlaßöffnung 19 immer nur in die vertikal zuoberst liegenden Saugkammern 17 der Bremswalzen 16, auf denen der Bogen 10 aufliegt, so daß keine falsche Luft angesaugt werden kann (Fig. 2).

The mode of operation and the handling for replacing the one-piece braking devices with those with a differently shaped arch supporting surface proceed as follows:

• The drive wheels 9 of the drive shaft 7 driven by the motor 8 transmit their rotational movement either by means of the drive belts 27 or the toothing to the brake rollers 16 and passes from there via the inner air inlet opening 19 only into the vertically uppermost suction chambers 17 of the brake rollers 16, on which the sheet 10 rests, so that no incorrect air can be drawn in (FIG. 2).

To replace the one-piece braking devices 5, the drive belts 27 are now lifted and stripped by hand from the drive grooves 18 and 26 of the drive wheels 9 and the brake rollers 16. Then the clamping screws 6 of the holder 12 are loosened, so that they are removed upwards from the one-piece carrier shaft 4 and counter. one-piece brake devices 5 can be replaced with brake rollers 16 narrower or wider design. These are then simply pushed back onto the one-piece carrier shaft 4 from above, for which purpose the guide groove 28 serves as a guide and support for the holder 12. As a result, the drive wheels 9 automatically face the brake rollers 16 in an alignment line. The newly installed brake devices 5 are determined by means of the clamping screws 6. Finally, the drive belts 27 are reinserted in the drive grooves 18 and 26 so that they span the drive wheels 9 and the brake rollers 16.

To move the one-piece braking devices 5 laterally onto pressure-free strips of the printed image, only the clamping screws 6 of the holders 12 have to be loosened and after their lateral positioning together with the drive wheels 9 which are only fixed in the circumferential direction, they have to be tightened again.

In a first embodiment of the invention according to FIG. 4, the carrier shaft 31 is formed in two parts and at the same time functions as a drive shaft. It is subdivided into a long carrier shaft part 32 and a short carrier shaft part 33, the drive being effected via the motor 8 flanged onto the side wall 2 onto the long carrier shaft part 32 mounted therein. The long support shaft part 32 must be shorter at its end facing the side wall 2 of the drive side of the machine by at least the width of a brake roller 34 on the two-part support shaft 31 of selectively spaced two-part brake devices 35 than the clear width between the two side walls 2 and 3 short carrier shaft part 33 for bridging from the long carrier shaft part 32 to the side wall 3 is designed as a stub shaft which can be pulled out of the side wall 3 by means of a handle 36. The short carrier shaft part 33 has at its end a shaft journal 37 which can be inserted into a bore 38 inserted into the end of the long carrier shaft part 32. The two carrier shaft parts 32 and 33 can thereby by means of a locking screw 39 or instead by means of other known locking elements, such as e.g. a ball catch, can be locked together.

According to FIGS. 5 to 8, a two-part brake device 35 each consists of one of the brake rollers 34 already mentioned above and a separate suction body 41 which can be plugged onto the brake roller 34 and which - depending on the width of the desired sheet support surface - is equipped with one or more suction chambers 42, which are connected via a suction air supply 43 to the vacuum generator, not shown and described in more detail. The absorbent body 41 is fixed to a bearing clamp 44, which is attached from above to a crossbar 45 fastened in parallel and horizontally in one plane to the two-part carrier shaft 31, but seen in the running direction of the sheet 10, in front of the same in the side walls 2 and 3. The bearing clamp 44 is fixed on the crossmember 45 by means of a tab 46 inserted below the bearing clamp 44, which is provided in the center with a locking screw 47.

The in a longitudinal groove 48 of the two-part Carrier shaft 31 slidably arranged brake rollers 34 are locked in the circumferential direction by means of driving screws 49. At the front end of the suction body 41 attached to the brake rollers 34, a rotatable deflection roller 51 is inserted in a bearing-shaped recess 50. The brake rollers 34 and the deflection rollers 51 are each spanned by at least one brake band 52, which is guided in grooves 53 embedded in the side of the brake rollers 34 (FIG. 5).

Depending on whether the brake rollers 34 of the two-part brake devices 35 are equipped with a narrow or wide sheet support surface, their structure differs. The brake rollers 34 with a narrow curved support surface 54 in FIGS. 4 to 6 have a continuous central web 55 and hub extensions 56 on both sides. The central web 55 of the brake rollers 34 with a narrow sheet support surface 54 is provided with a semicircular groove 53 in which the brake band 52 is embedded, by means of which the sheet 10 to be transported is braked. According to FIG. 4, a suction body 41 is used in this narrow design of the brake rollers 34, which is divided into two separate suction chambers 42 by a central recess and is plugged onto the central web 55 of the brake rollers 34, so that the two suction chambers 42 on both sides of the central web 55 come to rest on the hub lugs 56 of the brake rollers 34.

In the brake rollers 34 shown in FIGS. 7 and 8 with a wide arch support surface 58, a wide recess 59 is provided in the center, which is delimited by the two side walls 60, on each of which a brake band 52 rotates in grooves 53. In each case a suction body 41 with a single suction chamber 42 is inserted into the wide cutout 59 of the brake rollers 34 with a wide arc bearing surface 58.

• Zum Auswechseln der Bremswalzen 34 mit schmaler Bogentragfläche 54 gegen solche mit breiter Bogentragfläche 58 muß zuerst das einen jeden Mittelsteg und die Umlenkrolle 51 umspannende Bremsband 52 von Hand von der Umlenkrolle 51 abgehoben werden. Danach wird mittels der Feststellschrauben 47 die Arretierung der Saugkörper 41 mit ihrer Saugluftzuführung 43 soweit aufgehoben, daß die Laschen 46 den Lagerschellen 44 entnommen werden können. Die Saugkörper 41 können nun von oben von der Traverse 45 abgenommen werden.

The replacement of the previously described first embodiment of the two-part brake devices 35 proceeds as follows:

• To replace the brake rollers 34 with a narrow arch support surface 54 for those with a wide arch support surface 58, the brake band 52 spanning each central web and the deflection roller 51 must first be lifted from the deflection roller 51 by hand. Then the locking of the suction body 41 with its suction air supply 43 is released by the locking screws 47 to such an extent that the tabs 46 can be removed from the bearing clamps 44. The suction bodies 41 can now be removed from the cross member 45 from above.

Thereafter, the two-part carrier shaft 31 is separated by releasing the locking of the two carrier shaft parts 32 and 33 by the locking screw 39 and the stub shaft 33 can be pulled out of the remaining long carrier shaft part 32 and from the side wall 3 by means of the handle 36.

The brake rollers 34, which are secured only in the circumferential direction in the longitudinal groove 48, can then be pulled off from the long support shaft part 32 together with their brake bands 52 through the free-standing opening to the side wall 3, and instead brake rollers 34 with a wide arc bearing surface 58 can be pulled up. The newly used brake rollers 34 are now shifted laterally onto pressure-free areas of the printed image and are fixed by means of the locking screws 47. Then the plug-in width 33 is pushed back into the side wall 3, so that the shaft journal 37 comes to rest in the bore 38 of the long support shaft part 32. After the stub shaft 33 is locked again on the long carrier shaft part 32, the individual suction bodies 41 with their respective suction air supply 43 are plugged onto the cross member 45 from above and inserted into the wide recesses 59 of the brake rollers 34. The two brake bands 52 of the brake rollers 34 with a wide curved bearing surface 58 are now placed on the deflection rollers 51 again by hand. The two-part brake devices 35 assembled in this way are now ready for use.

It goes without saying that the flowchart of the sequence of the individual operations for exchanging the two-part brake devices 35 can be changed as desired, i.e. that e.g. first the suction body 41 with its suction air supply 4 and only then the brake rollers 34 can be exchanged or that this process can also take place in the reverse order.

In a second exemplary embodiment of the two-part brake devices 35 with a separable carrier shaft 31 shown in FIG. 6, the outgoing sheet 10 is decelerated by brake rollers 34 with a narrow sheet support surface 54. The carrier shaft 31 is designed in two parts, a clutch 66 being engaged between a drive pin 64 mounted in the side wall 2 and a long carrier shaft part 65 mounted in the side wall 3. To replace the two-part brake devices 35, the long carrier shaft part 65 must be uncoupled from the drive pin 64 and then pulled out of the side wall 3 by means of the handle 36 at least by the width of a brake roller 34. The two-part brake devices 35 themselves are exchanged as previously described.

According to FIG. 7, the carrier shaft 63 is constructed in three parts in a third exemplary embodiment of the two-part braking devices. It has a medium-long carrier shaft part 67, which is connected by means of two couplings 66 to the short drive journal 64 mounted in the side wall 2 and to a short bearing journal 68 arranged in the side wall 3. To the end Exchange of the two-part brake devices 35, the suction body 41 must first be separated from the brake rollers 34. This is done by lifting the brake bands' 52 out of the deflection rollers 51 of the suction bodies 41. Now the medium long carrier shaft 67 can be disengaged from the two clutches 66 and removed as a whole unit together with the brake rollers 34 from the machine, so that the actual replacement of the brake rollers 34 can be done outside the machine. The exchange of the suction body 41 on the cross member 45 is carried out separately, as already described above.

As shown in FIG. 8, in a fourth exemplary embodiment of the two-part braking devices 35, the carrier shaft 63 is likewise made in three parts. At the free end of the drive pin 64 mounted in the side wall 2, a joint 69 is fastened, to which the middle long support shaft part 70 is articulated. A short coupling pin 71 is mounted in the opposite side wall 3 and is connected to the other end of the central carrier shaft part 70 by the coupling 66. The short coupling pin 71 can be rotated or pulled out by means of the handle 36.

To replace the two-part brake devices 35, the suction bodies 41 are separated from the brake rollers 34 exactly as in the third exemplary embodiment. The middle long support shaft part 70 is then uncoupled by rotating or pulling out the short coupling pin 71 on the side wall 3 and can then be pivoted into any positions to replace the brake rollers 34, depending on the joint 69 used.

The invention is of course in no way limited to the embodiments shown in FIGS. 1 to 8 and laid down in the description, but can experience a wide variety of changes with regard to its structural details within its scope. Thus, it is entirely within the scope of the invention to make the carrier shaft 31, 63 separable or disengageable in the center or at any other location, or to arrange other suction brake rollers of the known type on the same.

Parts list

• 1 delivery pile
• 2 side wall
• 3 side wall
• 4 support shaft in two parts
• 5 one-piece braking device
• 6 clamping screw
• 7 drive shaft
• 8 engine
• 9 drive wheel
• 10 sheets
• 11
• 12 holders
• 13 bearing shell
• 14 suction air chamber sleeve
• 15 ball bearings
• 16 brake roller
• 17 suction chamber
• 18 drive groove
• 19 inner air inlet opening
• 20 outer air inlet opening
• 21 suction air supply
• 22 air inlet sleeve
• 23 grub screw
• 24 longitudinal groove
• 25 driving screw
• 26 drive groove
• 27 drive belts
• 28 guide groove
• 29 support collar
• 30 support shoulder
• 31 carrier frames in two parts
• 32 long carrier shaft part
• 33 short carrier shaft part
• 34 brake roller
• 35 two-part braking device
• 36 handle
• 37 shaft journals
• 38 hole
• 39 locking screw
• 40
• 41 absorbent body
• 42 suction chamber
• 43 Suction air supply
• 44 clamp
• 45 traverse
• 46 tab
• 47 locking screw
• 48 longitudinal groove
• 49 drive screw
• 50 deepening
• 51 pulley
• 52 brake band
• 53 groove
• 54 narrow arch wing
• 55 central bridge
• 56 hub attachment
• 57
• 58 wide arch wing
• 59 recess
• 60 side wall of the brake roller
• 61
• 62
• 63 carrier shaft, three parts
• 64 drive pins
• 65 long carrier shaft part
• 66 clutch
• 67 middle carrier shaft part
• 68 journals
• 69 joint
• 70 middle carrier shaft part
• 71 coupling pin

Claims (15)

1. A sheet delivery unit on printing machines with pneumatic braking means on the chain delivery system, the braking means being de- . signed as turning braking rollers, acted upon by suction, on a support shaft running under the chain conveyor cross-wise with respect to the sheet conveyer unit and short of the delivered stack, for braking and pulling tight the sheets as . they are delivered, characterised in that the braking means (5, 35) are designed to be exchanged against means with a differently formed sheet supporting surface.

2. A sheet delivery unit as claimed in claim 1, characterised in that the support shaft (4) is made in one piece and on it the braking means (5) are placed so that they may be taken off it and slipped onto it.

3. A sheet delivery unit as claimed in claim 1, characterised in that the support shaft (31, 63) is made up of a number of parts, able to be separated, on which the braking means (35) are placed so that they are able to be pulled off.

4. A sheet delivery unit as claimed in claims 1 and 3, characterised in that the support shaft (31, 63) is able to be separated into its parts and at least one shaft part (32 or 65 or 67 or 70) of the same may be unjoined.

5. A sheet delivery unit as claimed in claims 1, 3 and 4, characterised in that one support shaft part (32) at one of the two side walls (2 or 3) is shorter, to an amount at least equal to the breadth of the braking rollers (34), than the clearance breadth between the side walls (2 and 3) and in that as a bridging over element with respect to the side wall (3) a support part (33) is used, which is able to be pulled out.

6. A sheet delivery unit as claimed in claims 1, 3 and 4, characterised in that one support shaft part (65) may be unjoined from a clutch (66), placed at the side wall (2), and is so placed that it may be pulled out of the opposite side wall (3).

7. A sheet delivery unit as claimed in claims 1, 3 and 4, characterised in that a middle support shaft part (67) is placed so that it may be pulled out of clutches (66) at its two ends.

8. A sheet delivery unit as claimed in claims 1, 3 and 4, characterised in that one end of a middle support shaft part (70) is bearinged in a joint (69) and the other end may be unjoined from a clutch (66) and may be turned down about the joint (69).

9. A sheet delivery unit as claimed in claim 1 and claim 2, characterised in that the braking means (5) are of single-piece design, taking the form of braking rollers (16) with machined-out suction spaces (17) and an integral suction air inlet (21), driving of the braking rollers (15) taking place by way of separate driving wheels (9).

10. A sheet delivery unit as claimed in claim 9, characterised in that the braking rollers (16) are placed turningly, and the suction inlets (21) are placed unmovingly, at the ends of supporters (12) able to be slipped on to the support shaft (4).

11. A sheet delivery unit as claimed in claims 9 and 10, characterised in that driving of the brake rollers (16) takes place, in each case, by way of at least one turning driving belt (27) of the driving wheels.

12. A sheet delivery unit as claimed in claims 1, and 3 to 8, characterised in that the braking means (35) are two-parts in design, taking the form of braking rollers (34) with, in each case, a separate suction body (41), able to be slipped onto the rollers (34), having a suction inlet (43), which is placed, in a way able to be locked and taken off, on a separate cross-piece (45) running parallel to the support shaft (31).

13. A sheet delivery unit as claimed in claim 12, characterised in that as a braking element of the braking rollers (34) at least one thin brake band (52) is used, placed round the brake, rollers (34) at their suction bodies (41), the brake belt (42) braking the printed material which is to be slowed down.

14. A sheet delivery unit as claimed in claims 12 and 13, characterised in that in the case of braking rollers (34) with a narrow sheet support surface (54) the suction body (41) has two suction spaces (42) placed on the two sides of one single brake band (52) stretching round the braking rollers (34).

15. A sheet delivery unit as claimed in claims 12 to 14, characterised in that in the case of braking rollers (34) with a broad sheet support surface (58) the suction body (41) has a single suction space (42) placed between two braking bands (52) placed round the braking rollers (34).

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