DEVICE AND METHOD FOR STORING A PRESSURE CYLINDER

Description

[0001] The invention relates to a printing unit comprising a plurality of printing cylinders, wherein at least one printing cylinder is rotatably mounted in a bearing position on a first side by means of a first bearing unit and on a second side by means of a second bearing unit in an operating state, wherein the first bearing unit can be disengaged and, by means of an adjusting device connected to the first bearing unit, can be set off for setup purposes and can be brought back into the bearing position and engaged to restore the operating state.

[0002] Furthermore, the invention relates to a method for receiving a first bearing journal of a pressure cylinder by a first bearing unit, wherein the first bearing unit, which is movable by means of an adjusting device connected to the bearing unit, is brought into a bearing position in which the first bearing unit can be slid onto the first bearing journal of the pressure cylinder.

[0003] Printing devices are known from the prior art in which a change of the functional surface and / or the circumference of at least one printing cylinder is possible, for example by means of printing form sleeves, sleeves for changing the transfer cylinder or sleeves of different thicknesses to change the cylinder circumference and thus the printing length.

[0004] In this context, the term "printing cylinder" refers to all cylinders used in printing processes known from the prior art. A printing cylinder can therefore be, for example, a printing form cylinder (also called a plate cylinder in offset printing), a transfer cylinder (also called a rubber cylinder in offset printing because of its covering with a printing blanket called a rubber blanket), or an impression cylinder.

[0005] If such sleeve-shaped sleeves need to be replaced, this is only possible by sliding the sleeve laterally onto the corresponding printing cylinder, due to the sleeve being closed in the circumferential direction.

[0006] For example, EP 2 388 141 A2 discloses a format-variable printing unit in which a plurality of printing cylinders are arranged in a spatially variable manner in order to be able to exchange or change the corresponding printing cylinders.

[0007] DE 199 37 796 A1 discloses a printing unit concept in which the printing cylinders are mounted in linear guides so that they can be adjusted relative to each other, so that the distance between the cylinders can be adjusted when the cylinder diameter is changed.

[0008] EP 0 656 259 B1 discloses a printing unit with a plurality of printing cylinders, wherein a printing cylinder comprises a rigid mandrel and a sleeve rotatably mounted thereon by means of two bearings, and wherein, for the purpose of replacing the sleeve, it is pulled away from the mandrel which is mounted on one side together with the two bearings.

[0009] US Patent 5,601,021 A discloses a printing unit with a plurality of printing cylinders, wherein in an operating state a printing cylinder is supported on both sides in side walls and includes an interchangeable sleeve on its outer surface, wherein to replace the sleeve the side wall in the area of ​​the first bearing is opened so that the sleeve can be changed over the first bearing while the cylinder is supported in a second bearing, and wherein to ensure a constant position of the printing cylinder when the first side wall is open the cylinder is additionally supported in the area of ​​the second bearing.

[0010] JP H10-305558 A discloses a printing unit with at least one printing cylinder, wherein in an operating state a printing cylinder is mounted on both sides in side walls and includes an interchangeable sleeve on its outer surface, wherein, to replace the sleeve, the entire cylinder is first raised on both sides, i.e., on a first side and on a second side, wherein, to replace the sleeve, the lifting device on the first side is removed from the cylinder so that the sleeve can be changed in the direction of the first side while the cylinder continues to be raised on the second side, and wherein, to ensure a horizontal position of the printing cylinder, it is additionally supported from above in the area of ​​the second side.

[0011] In printing presses known from the prior art, a printing cylinder is supported on both sides, that is, on both sides of the functional surface. With such double-sided support, which is particularly necessary for medium and large web widths to achieve print quality, a printing cylinder includes a second bearing journal on its other side, on which a second bearing, usually a roller bearing, is arranged. This second bearing is located within a second bearing unit. The second bearing unit can, for example, be the side wall or be arranged in the side wall, provided that the printing cylinder's spatial position is not to be changed or is to be changed only slightly. In contrast, with spatially adjustable printing cylinders, the second bearing unit is arranged to be spatially adjustable relative to the side wall.Such a pressure cylinder further comprises on its first side a first bearing journal, which is supported in a first bearing unit, which is usually also designed as a rolling bearing. The first bearing unit includes both the corresponding rolling bearing and a receptacle for this bearing.

[0012] To replace the elevator or a closed sleeve on the printing cylinder, the first bearing unit, viewed along the cylinder's longitudinal axis, must be removed from the cylinder. This is also known as disengaging the first bearing unit. For example, the first bearing unit is pulled lengthwise from the first bearing journal of the printing cylinder. Then, using an adjustment mechanism, the first bearing unit is moved in a plane perpendicular to the cylinder's longitudinal axis, allowing access to the cylinder along its longitudinal axis and enabling its reconfiguration. While the first bearing unit is disengaged from the printing cylinder, the cylinder is typically held solely by the second bearing unit. It is also possible that the printing cylinder is additionally supported by the second bearing unit.

[0013] After the conversion process, such as changing a sleeve located on the printing cylinder, the printing cylinder must be stored again in the first bearing unit, whereby the first bearing unit, if necessary with the first bearing installed in it, is moved into the original position, so that the first bearing unit is then pushed onto the first bearing of the printing cylinder in the direction of the longitudinal axis of the printing cylinder.

[0014] However, particularly with very long and / or very slim printing cylinders, the problem arises that, due to the unavoidable bending of the printing cylinder and / or the bearing clearance required for function and service life in the second bearing unit, the position of the first bearing journal deviates slightly from its original position after removal of the first bearing unit when supported on both sides. This can lead to problems when sliding the first bearing unit onto the first bearing journal, such as tilting or the risk of damage to the running surfaces of the first bearing.

[0015] The object of the present invention is therefore to find a solution for gently sliding the first bearing unit onto the first bearing journal and to avoid tilting and damage to the first bearing or the bearing seats and running surfaces of the first bearing journal.

[0016] The present problem is solved by a device according to claim 1 and by a method according to claim 11.

[0017] The problem is solved by a device in which the first bearing unit and / or the adjusting device connected to the first bearing unit comprises at least one driver, wherein the at least one driver can be brought into contact with the associated pressure cylinder at least temporarily when the first bearing unit is moved into the bearing position in order to lift the pressure cylinder.

[0018] The problem is solved by a method in which, when the first bearing unit is moved into the bearing position, the pressure cylinders are supported at least temporarily by at least one driver attached to the adjusting device connected to the first bearing unit and / or to the first bearing unit.

[0019] These solutions have the advantage that, with very little technical effort, without additional control engineering effort and regardless of the extent of the displacement of the first bearing journal of the printing cylinder, the printing cylinder can be brought into a position in which the first bearing unit can be pushed onto the first bearing journal of the printing cylinder without the risk of tilting and without the risk of damage.

[0020] According to one embodiment of the invention, the at least one driver is arranged without contact with the printing cylinder in the operating state, meaning that the driver is not in contact with the printing cylinder during operation. This embodiment has the advantage that no wear can occur on the printing cylinder or on the at least one driver, and that no disruptive factors can occur during printing.

[0021] According to a further embodiment of the invention, the adjustment device performs a linear movement or a pivoting movement. The solution according to the invention is therefore applicable to all known variable-format printing units, regardless of the positioning movement of the first bearing unit and / or the corresponding printing cylinder.

[0022] According to a further embodiment of the invention, the at least one driver is designed to be immovable. This embodiment, in which the at least one driver is immovably and thus statically attached to the first bearing unit or to the adjusting device, offers the advantage of a technically simple, maintenance-free and consequently also very cost-effective solution.

[0023] According to a further embodiment of the invention, the at least one driver is movably designed. Although this embodiment requires a somewhat more complex technical solution, it allows the driver to be positioned in such a way that the first bearing journal of the pressure cylinder is very precisely aligned with the first bearing unit, and that after the first bearing unit has been slid onto the first bearing journal, the at least one driver can be disengaged from the pressure cylinder, so that there is no longer any contact between the at least one driver and the pressure cylinder.

[0024] According to a further embodiment of the invention, the at least one driver is designed as a stud bolt and / or has the structure of a ring segment. This embodiment offers the advantage of a very cost-effective and technically simple retrofit solution.

[0025] According to a further embodiment of the invention, the at least one driver comprises a rotatable element, such as a rotatably mounted sleeve or a rolling bearing, which is at least temporarily in contact with the pressure cylinder. Such an embodiment has the advantage that, when the at least one driver is in contact with the pressure cylinder, a rotary movement of the pressure cylinder is possible without impairments such as friction or wear.

[0026] Preferred embodiments of the invention are described in the dependent claims and the following description. Various exemplary embodiments of the invention are explained in more detail with reference to the drawings, without being limited thereto. These show: Fig. 1 A basic structure of an exemplary printing unit. Fig. 2 A basic structure of a printing cylinder including bearings on both sides. Fig. 3 A printing cylinder with a first bearing unit in place. Fig. 4 A printing cylinder mounted in the second bearing unit with corresponding bearing clearance. Fig. 5 A printing cylinder with the driver in contact. Fig. 6 A printing cylinder immediately before the first bearing unit is slid onto it. Fig. 7 A printing cylinder after the first bearing unit has been slid onto the first bearing journal. Fig. 8 An exemplary embodiment of the driver. Fig. 9 Another exemplary embodiment of the driver.

[0027] Fig. 1Figure 1 shows the basic structure of an exemplary printing unit 1. This unit comprises a plurality of printing cylinders 2 arranged essentially one above the other, with the substrate web 12 running between two printing cylinders 2. In the case of the configuration of the printing unit 1 as an offset printing unit for single-sided printing of the substrate web 12, the upper printing cylinder 2, which is in contact with the inking rollers arranged above it, is designed as a plate cylinder or form cylinder, whereas the middle printing cylinder 2 is designed as a transfer cylinder, which is also referred to as a rubber cylinder. The lowest printing cylinder 2 shown is designed as an impression cylinder in an offset printing unit.However, since the present invention is applicable to all corresponding printing cylinders 2 regardless of the design of the printing cylinders 2, the term printing cylinder 2 will be used exclusively below for all such printing cylinders 2, which are also used in modified form in printing units 1 for other printing processes.

[0028] If the section length of so-called variable-format printing units 1 needs to be changed, the diameters and thus the circumferences of the corresponding printing cylinders 2 are exchanged. Referring to the in Fig. 1In the example shown, the diameters of the upper and middle printing cylinders 2 would be changed by exchanging the sleeves 10 attached to the respective printing cylinders 2. Due to the closed surface of such sleeves 10, these sleeves 10 can only be removed from the end face of a corresponding printing cylinder 2. Because of the variable diameters of such printing cylinders 2, either these printing cylinders 2 with variable diameters and / or the adjacent printing cylinders 2 are mounted in a correspondingly adjustable manner. This can be achieved, for example, by mounting the relevant printing cylinder(s) 2 in or on levers so that they are adjustable.

[0029] At the in Fig. 1In the example shown, the middle pressure cylinder 2 is mounted on the upper pivotally mounted lever, which serves as an adjusting device 8, and is adjusted along with the pivoting movement of the adjusting device 8, symbolized by a curved arrow. In the example shown... Fig. 1 In the illustrated example, the lower pressure cylinder 2 is mounted in the lower adjustment device 8 so that it can be moved linearly and thus its position can be changed. The adjustment device 8 can, however, be designed in any way, namely as a pivoting lever, as two levers pivoting relative to each other, and / or as an adjustment device 8 mounted in a linear guide.

[0030] The upper printing cylinder 2, designed as a form cylinder, can, for example, be in the in at least one side Fig. 1 The cylinder may be mounted on the side wall not shown in the drawing, provided that this pressure cylinder 2 does not need to be changed spatially or only slightly in its position.

[0031] Fig. 2Figure 1 shows a top view of an exemplary bearing arrangement for an arbitrary pressure cylinder 2 on which a sleeve 10 is mounted. The cylinder 2 is rotatably mounted about its longitudinal axis 13. For this purpose, the pressure cylinder 2 includes a first bearing journal 4, the first bearing journal 4 being mounted in a first bearing unit 6. The first bearing unit 6 comprises both the bearing, which is usually designed as a rolling bearing, and the associated housing in which the bearing is held. Since it is completely irrelevant for the present invention whether and how the bearing is arranged in the bearing housing, the term "first bearing unit 6" is used exclusively below, encompassing both the bearing and the housing in which the bearing is arranged. It is also possible for the bearing to be split, so that the inner ring of the bearing is mounted on the first bearing journal 4, while the rolling elements and the outer ring remain in the housing.Even in such a case, due to their lack of relevance to the present invention, only the terms first bearing journal 4 and first bearing unit 6 are used.

[0032] The first bearing unit 6 is connected to an adjustment device 8, which can be designed, for example, as a pivoting lever or as a linearly movable element. The adjustment device 8 serves to change the position of the first bearing unit 6 in a substantially stationary pressure cylinder 2, in order to enable the sleeve 10 to be changed.

[0033] In the case of a variably mounted printing cylinder 2, the adjustment device 8 serves both to stop the first bearing unit 6, for example to change the sleeve 10, and to change the spatial position of the printing cylinder 2 with the first bearing unit 6 mounted on the printing cylinder 2, in order to be able to change the position of the printing cylinder 2 required for printing in the case of sleeves 10 of different thicknesses.

[0034] At the in Fig. 2 The exemplary pressure cylinder 2 includes, on the side facing away from the first bearing journal 4, a second bearing journal 5 on which the pressure cylinder 2 is rotatably mounted in a second bearing unit 7. In the case of the Fig. 2 as well as in the Figures 3 to 7In the exemplary illustration of the printing cylinder 2, the second bearing unit 7 is fixedly installed in the side wall 11, although it should be noted that the second bearing unit 7 can also be designed to be movable, for example if the printing cylinder 2 needs to be changed in its spatial position relative to the other printing cylinders 2 in order to adapt to sleeves 10 of different thicknesses for printing.

[0035] The in Fig. 2 The position of the first bearing unit 6 shown is referred to as the bearing position, since the pressure cylinder 2 is stably mounted here and the first bearing unit 6 is aligned with the second bearing unit 7.

[0036] Fig. 3 shows a state of pressure cylinder 2. Fig. 2, in which the first bearing unit 6 is detached from the end face of the bearing. For this purpose, the first bearing unit 6 is first pulled away from the first bearing seat by a length a in the axial direction, i.e., in the direction of the longitudinal axis 13 of the printing cylinder 2, so that the first bearing is no longer seated on the first bearing journal 4. This process is also referred to as disengaging the first bearing unit 6. After the first bearing unit 6 has been pulled away from the first bearing journal 4 in the axial direction, it is moved by a distance y in a direction perpendicular to the longitudinal axis 13 of the printing cylinder 2, so that the end face of the printing cylinder 2 is no longer covered by the first bearing unit 6. In this state, the first bearing unit 6 is in a sleeve-change position, since in this sleeve-change position the sleeve 10 can be pulled off or pushed onto the printing cylinder 2.

[0037] Fig. 4Figure 1 shows the state of the printing cylinder 2 after the first bearing unit 6 is pivoted and / or after a sleeve 10 is replaced. Due to the bearing clearance required for operation in the second bearing unit 7, in which the printing cylinder 2 is thus exclusively held, and / or due to possible deflection, especially in the case of very long and very slender printing cylinders 2, the first bearing journal 4 sags downwards by the amount Δy relative to the bearing position when the first bearing unit 6 is in the off position, which is shown in Fig. 4This is illustrated by the fact that the longitudinal axis 13 of the pressure cylinder 2, in the area of ​​the first bearing journal 4, is no longer located at the bearing position marked by dimension y, but is offset downwards by dimension Δy. Such positional deviations of the first bearing journal 4 from its bearing position, caused by the bearing clearance of the second bearing unit 7 and / or by the deflection of the pressure cylinder 2, are unproblematic with appropriate bearing design, but can lead to problems when sliding the first bearing unit 6 back into position.

[0038] Fig. 5 shows the pressure cylinder 2 with the first bearing unit 6 switched off, wherein the first bearing unit 6 is opposite the one in Fig. 3 and Fig. 4 The position shown has been adjusted essentially by the amount y-Δy in the direction perpendicular to the longitudinal axis 13 of the pressure cylinder 2, and thus has not yet reached the height of the bearing position.

[0039] As from Fig. 5 evidently, includes in the Fig. 5 In the example shown, the adjusting device 8 has a driver 9, which is designed such that this driver 9 can be brought into contact with the corresponding associated pressure cylinder 2 at least temporarily when the first bearing unit 6 is moved into the bearing position, i.e. when the first bearing unit 6 reaches a position shortly before the height of the bearing position, in order to be able to raise it essentially by the amount Δy.

[0040] Although in Fig. 5 If an embodiment is shown in which the driver 9 is attached to the adjusting device 8, such as a swivel arm or a linear guide, it is also possible to attach the driver 9 to the first bearing unit 6.

[0041] Fig. 5Figure 1 shows an embodiment in which only one driver 9 is arranged on the adjusting device 8. However, it is also possible to attach a plurality of drivers 9, such as a plurality of studs or elements attached to studs, to the adjusting device 8 and / or to the first bearing unit 6.

[0042] Fig. 6 shows the printing cylinder 2 from Fig. 5 , where the first storage unit 6 is opposite Fig. 5 The pressure cylinder 2 was raised by the amount Δy perpendicular to the longitudinal axis 13, so that the pressure cylinder 2 is essentially in its bearing position, since the pressure cylinder 2 was also raised by the amount Δy by the driver 9, as the pressure cylinder 2 is supported on the driver 9, at least during this period and thus temporarily. In the case of the Figures 4 to 7In the example shown, the pressure cylinder 2 is in contact with the driver 9 in the area of ​​its pin 3, however, it is arbitrary where the pressure cylinder 2 rests on the driver 9.

[0043] As from Fig. 6 As can be seen, by supporting the pressure cylinder 2 on the driver 9, the longitudinal axis 13 of the pressure cylinder 2 and the first bearing unit 6 are again in an alignment which is sufficient to allow the first bearing unit 6 to be pushed onto the first bearing journal 4 without tilting and without damage to the bearing of the first bearing unit 6 or the first bearing journal 4.

[0044] Fig. 7 shows the printing cylinder 2 from Fig. 6 , whereby in Fig. 7In the depicted state, the first bearing unit 6 is fully pushed onto the first bearing journal 4 and thus fully engaged again, so that the driver 9 is also moved on the journal 3 towards the second bearing journal 5, since the driver 9 engages the pressure cylinder 2 on the journal 3 and supports it there. The pressure cylinder 2 is thus fully supported again by the first bearing unit 6 and the second bearing unit 7 and is therefore ready for operation.

[0045] In the Fig. 7In the depicted state, the pressure cylinder 2 is in an operating state, as it is in its storage position, fully supported, and thus basically ready for operation. In this state, the driver 9 can either still be in contact with the pressure cylinder 2, preferably with a pin 3 of the driver 9. However, it is advantageous if, in this operating state, the driver 9 is arranged without contact with the pressure cylinder 2 or the pin 3 of the pressure cylinder 2. This can be achieved, for example, by having a small gap of, say, a few tenths of a millimeter between the driver 9 and the pressure cylinder 2.Such a gap means that the pressure cylinder 2 is not positioned exactly in its bearing position before the second bearing unit 7 engages the first bearing journal 4. However, such minor deviations do not cause any problems or damage when sliding the first bearing unit 6 onto the first bearing journal 4, especially if the first bearing journal 4 has a chamfer or bevel. Rather, such a non-contact arrangement of the driver 9 to the pressure cylinder 2 offers the advantage of no wear and avoidance of other potential problems such as oscillations or vibrations.

[0046] The driver 9 can be designed to be either movable or fixed. A fixed design has the advantage of being simple and cost-effective; however, if the driver 9 is arranged without contact with the pressure cylinder 2 in the operating state, the pressure cylinder 2 is not positioned exactly in its bearing position before the first bearing unit 6 is slid onto the first bearing journal 4.

[0047] However, if the required tolerances of the first bearing necessitate precise alignment of the longitudinal axis 13 of the pressure cylinder 2 with the first bearing unit 6, it is also possible to design the driver 9 to be movable. For example, the driver 9 can be adjusted or pivoted towards the pressure cylinder 2 to temporarily lift it when the first bearing unit 6 is moved into the engagement position, so that after the second bearing unit 7 is slid into place, at least one driver 9 is again moved away from the pressure cylinder 2 or pivoted away to be positioned without contact with the pressure cylinder 2 in the operating state.

[0048] Although not in the Figures 4 to 7As shown, it is also possible to additionally or alternatively adjust the driver 9 in the extension of the longitudinal axis 13 of the pressure cylinder 2, so that the required area for at least temporarily supporting the driver 9 on the pressure cylinder 2 is reduced, so that it is less in the extension of the longitudinal axis 13 than the adjustment movement of the first bearing unit 6 in the extension of the longitudinal axis 13.

[0049] Fig. 8Figure 1 shows an exemplary embodiment of a driver 9, in which the driver 9 has the contour of a ring segment, so that the pressure cylinder 2 or a pin 3 of the pressure cylinder 2 can be securely supported on the driver 9. The ring-segment-shaped driver 9 can, for example, be attached to the adjusting device 8 and / or to the first bearing device 6 by means of studs. However, it is also possible to design the driver 9 as at least one stud, which supports the pressure cylinder 2 when it is moved into the bearing position.

[0050] Fig. 9 Figure 1 shows an exemplary embodiment in which the driver 9 is designed in two parts and has a substantially V-shaped contour, so that the pressure cylinder 2 or a pin 3 of the pressure cylinder 2, which can be a form cylinder or a transmission cylinder, can assume a stable position in it when supported.

[0051] The contour of the at least one driver 9 can in principle be chosen arbitrarily, provided that it enables secure support of the pressure cylinder 2, which depends in particular on whether the adjusting device 8 and thus also the first bearing unit 6 attached to it performs a linear or arc-shaped movement.

[0052] The driver 9 can in principle be made of any dimensionally stable material; preferably the driver 9 is made of metal, plastic or a composite material.

[0053] Although not in the Figures 8 and 9As shown, it is also possible that the driver 9 comprises at least one rotatable element, such as a rotatably mounted disc, a rotatably mounted ring, or a rolling bearing, wherein the rotatable element is brought into operative connection with the pressure cylinder 2. Thus, it is possible that during the sliding of the first bearing unit 6 onto the first bearing journal 4, the pressure cylinder 2 is set into rotational motion to facilitate easier engagement of the first bearing unit 6.

Claims

1. Printing unit (1) comprising a plurality of printing cylinders (2), wherein at least one printing cylinder (2) is mounted in an operating state in a bearing position on a first side by means of a first bearing unit (6) and on a second side by means of a second bearing unit (7) on a second side, wherein the first bearing unit (6) can be disengaged and, for set-up purposes, can be moved out of position by means of an adjustment device (8) connected to the first bearing unit (6) and can be moved back into the bearing position and engaged again to establish the operating state, characterised in that the first bearing unit (6) and / or the adjustment device (8) connected to the first bearing unit (6) comprises at least one driver (9), wherein the at least one driver (9) can be brought into contact, at least temporarily, with the associated printing cylinder (2) for lifting the printing cylinder (2) when the first bearing unit (6) is moved into the bearing position.

2. Printing unit (1) according to claim 1, characterised in that the at least one driver (9) is arranged in a non-contact manner with respect to the printing cylinder (2) in the operating state.

3. Printing unit (1) according to one of claims 1 or 2, characterised in that the adjustment device (8) performs a linear movement or a swivelling movement.

4. Printing unit (1) according to one of claims 1 to 3, characterised in that the at least one driver (9) is designed to be immovable.

5. Printing unit (1) according to one of claims 1 to 3, characterised in that the at least one driver (9) is designed to be movable.

6. Printing unit (1) according to one of claims 1 to 5, characterised in that the at least one driver (9) is designed as at least one stud bolt and / or has the contour of a ring segment.

7. Printing unit (1) according to one of claims 1 to 5, characterised in that the at least one driver (9) comprises at least one rotatable element.

8. Printing unit (1) according to one of claims 1 to 7, characterised in that the at least one driver (9) engages with a pin (3) of the printing cylinder (2).

9. Printing unit (1) according to one of claims 1 to 8, characterised in that the driver (9) is made of metal, plastic or a composite material.

10. Printing unit (1) according to any one of claims 1 to 9, characterised in that the printing cylinder (2) is a forming cylinder or a transfer cylinder.

11. Method for accommodating a first bearing pin (4) of a printing cylinder (2) by means of a first bearing unit (6), wherein the first bearing unit (6), which can be moved by means of an adjustment device (8) connected to the first bearing unit (6), is brought into a bearing position in which the first bearing unit (6) can be pushed onto the first bearing pin (4) of the printing cylinder (2), characterised in that, when the first bearing unit (6) is moved into the bearing position, the printing cylinder (2) is supported, at least temporarily, by at least one driver (9) attached to the adjustment device (8) connected to the first bearing unit (6) and / or to the first bearing unit (6).