Abstract:
The invention relates to an assembled undular brake disc having a hub on which two friction rings which are produced from a steel material are arranged parallel to and spaced apart from one another. The assembled undular brake disc can withstand high mechanical loads and permits good internal ventilation. Supporting bolts for absorbing an axially acting pad contact pressure force are arranged between the friction rings.

Description:
FIELD OF INVENTION 
     The present invention relates to a built shaft brake disc having a hub, on which two friction rings are arranged parallel to and spaced from one another. 
     BACKGROUND OF THE INVENTION 
     Built shaft brake discs are employed in particular for rail vehicles, and through the built shape of the shaft brake discs these can be assembled from multiple individual components. 
     A built shaft brake disc is to mean a shaft brake disc which is put together of at least two components. Here, a built shaft brake disc is to describe in particular a brake disc that has two friction rings which are not formed in one piece and structure-uniformly with one another, for example as is known in a casting method, but which are individually provided and preferably assembled into a friction ring pair by further elements. As a further individual part, the hub in this case can be joined to the friction ring pair in the assembly. 
     Known are for example shaft brake discs having a hub, on which two friction rings are attached parallel to and spaced from one another. Between the friction rings, supporting pins or bolts can extend which are embodied to absorb axially acting pad contact pressure forces. In particular in the case of heavy rail vehicles, the pad contact pressure forces which are applied onto the friction ring pair by the brake linkage via the brake pads can reach very high values. From this results the requirement of embodying shaft brake discs with supporting pins or bolts arranged between the friction rings in a suitably stiff and mechanically highly loadable manner. 
     In addition to this, good heat removal is required and it is frequently provided that an airflow is generated which axially flows onto the shaft brake disc for example on the hub side and flows out radially on the outside. By way of this air throughput the brake disc can be cooled through heat convection and the airflow is generated through the rotation of the shaft brake disc about its axis of rotation. In particular in the case of cast shaft brake discs, casting geometries between the friction rings are known, which simulate the geometry of a radial fan, so that the corresponding air throughput by way of the shaft brake disc is obtained. 
     Substantially two types of ventilation are distinguished, the described radial ventilation type and a tangential ventilation type. If a shaft brake disc has supporting pins or bolts between the friction rings, these bring about a rather tangential ventilation. Through the rotation of the shaft brake disc the surface of the supporting pins or bolts is subjected to a tangential incident flow, as a result of which heat is discharged through convection. Here, the effect can be observed that the flow medium likewise slightly flows from the inner diameter to the outer diameter, as is also the case with the radial fan. However, this effect plays only a subordinate role so that substantially an axial airflow is obtained. Important here is an optimal arrangement and dimensioning of the supporting pins or bolts so that major heat dissipation is achieved. 
     In particular, built shaft brake discs are known as ceramic brake discs which comprises friction rings of a ceramic material, generally however of a material from the group of carbons. Frequently the hub of such non-metallic brake discs is produced from a steel material, and elaborate connecting geometries are required in order to avoid heat-induced distortions between the ceramic or carbon material and the metallic hub for receiving the friction rings. 
     PRIOR ART 
     From DE 195 07 922 C2 a built shaft brake disc is known, which comprises two friction rings which are arranged parallel to and spaced from one another on a hub, which friction rings can be flame-cut out of a plate in a simple manner. Between the friction rings is located a fan insert, which serves for improving the cooling on the inside of the friction rings. In order to receive axially acting pad contact pressure forces for the braking operation, the shown fan insert however is unsuitable and axial forces which are generated through the brake caliper via the brake pads onto the friction rings have to be absorbed via the connection of the friction rings to the hub. For this reason, a design of a shaft brake disc which has a rather lower mechanical load capacity is obtained. 
     From DE 195 43 799 A1 a further built shaft brake disc is known, and between friction rings produced from a material from the group of carbons supporting pins or bolts extend in order to absorb the high axially acting pad contact pressure forces. Here, the bolts are embodied with a collar, as a result of which pad contact pressure forces can be positively transmitted. Such a construction is known for built shaft brake discs with friction rings, which are produced of ceramics or a material from the group of the carbons. The built form of the shaft brake disc is used in particular because positively joined connections between the friction rings of a material from the group of carbons to a hub, which is produced from a steel material as a rule, cannot be used in a simple manner. Consequently, screw connections or other non-positively joined or positively joined connecting techniques are employed, wherein in the assembly joint between the friction rings and the hub frequently elements are additionally arranged which offset the different thermal expansion between the hub of a steel material and the friction rings of ceramics or a material from the group of the carbons, for example formed by slot nuts. 
     SUMMARY OF THE INVENTION 
     It is therefore the object of the present invention to provide a built shaft brake disc with friction rings of a steel material, which can withstand high mechanical loads and makes possible good internal ventilation. This object is solved with a built shaft brake disc, comprising a hub, on which two friction rings produced from steel material are arranged parallel to and spaced from one another, and supporting pins or bolts arranged between the friction rings for absorbing an axially acting pad contact pressure force. 
     The invention includes the technical teaching that the built shaft brake disc is constructed with a hub and two friction rings produced from a steel material, which are arranged parallel to and spaced from one another on the hub, wherein between the friction rings supporting pins or bolts for absorbing an axially acting pad contact pressure force are arranged. 
     Here, the friction rings can constitute a separate assembly that can be assembled independently of the hub and form a friction ring pair jointly with the supporting pins (or bolts). This assembly can then be connected to the hub by way of known methods, which hub in turn constitutes an independent component. Accordingly, friction ring and hub can be produced and provided independently of one another. This offers an advantage above all during the replacement of friction ring pairs on a hub. 
     The built shaft brake disc thus comprises multiple individual parts, which are formed at least by one hub, two friction rings produced from a steel material and a number of supporting pins. Similar to the construction of a ceramic or carbon brake disc, also known under the term carbon brakes, a shaft brake disc according to the invention can also be provided as a built brake disc, with which all functionally essential components consist of a steel material. In particular the friction rings can advantageously be cut out of a steel plate, for example by means of laser beam cutting, by means of water jet cutting or another thermal or abrasive cutting method, but the friction rings can also be mechanically cut out of a steel plate. The bolts can be produced from any materials, however preferentially also from steel. The hub in particular can be produced from steel in order to avoid heat expansion-induced distortions with a shaft, on which the shaft brake disc is mounted. 
     As a result, a built shaft brake disc is provided according to the invention which can be assembled from various materials in the manner of a modular system. In addition to the free material selection it is advantageous in addition that the geometry of the friction ring pair and/or the hub can be changed as desired. Because of this, the friction ring pair can be very rapidly adapted to changed peripheral conditions and differently embodied friction ring pairs can be mounted and demounted from a single hub through quick replacement. 
     However, the friction rings are formed in particular from a steel material, wherein at least in the case of the supporting pins a free material selection is made possible in order to optimise the individual components of the shaft brake disc with respect to their mechanical and thermal loads. Finally, the weight of the shaft brake disc can be further optimised since geometries can be employed which from a casting point of view cannot be produced strictly speaking. 
     Advantageously, the friction rings can comprise poles into which the supporting pins are inserted at the end side. The supporting pins can be designed rotation-symmetrically and have a middle portion and pins on the end side. During the assembly of the shaft brake disc, the pins of the supporting pins on the end side can be inserted into the holes in the friction rings. The length of the pins in this case determines the thickness of the shaft brake disc, which can for example be 80 mm. 
     The middle portion of the supporting pins can be larger than the diameter of the pins on the end side or the middle portion of the supporting pins is designed smaller than the diameter of the pins on the end side. In particular, it can be advantageous to provide supporting pins having a middle portion with a smaller diameter. This serves to accommodate the tolerance of the plates. In addition, inspection of the weld seam is possible. In addition, the thickness of the friction rings can be offset without additional mechanical machining being required. 
     The connection between the support bolts and the friction rings, in particular between the pins on the end side, which are inserted into the holes of the friction rings, can be produced through a press-fit connection, through a soldered connection, through a welded connection or through a riveted connection. Finally, a screw connection can also be advantageously produced using connecting screws. If the connection between the supporting pins and the friction rings consists of a soldered connection, this can be produced for example through high-temperature soldering or brazing. Here, soldering temperatures can be employed which do not occur during the normal operation of the brake disc. 
     If the connection between the supporting pins and the friction rings is produced through a welded connection, laser beam welding, electron beam welding or further possible welding methods can be employed here for example. Especially with the electron beam welding, the thermal input in the components to be joined is minimal, so that only a minimal thermal distortion through the welding method can develop in particular in the friction rings and which is why this method is to be advantageously employed. Through the materially joined connection it is advantageously achieved that the heat which develops in the friction rings through the operation of the shaft brake disc can be directed into the supporting pins so that the heat can be particularly effectively discharged through the internal ventilation. 
     With particular advantage, the soldered connection can be produced in a suitable oven, wherein at the same time the high-temperature soldering can be accompanied by a heat treatment for example of the friction rings. Through this connecting technology the advantage is obtained that with the connecting process, namely the high-temperature soldering, a hardening process of the further components, in particular of the friction rings, can also be created. Because of this, multiple advantages are achieved since an optimal material is created which is no longer changed in its material properties through subsequent machining or connecting operations and it can be achieved that by creating the connection in addition to the hardening in one operation a production advantage also in terms of cost is achieved. 
     It is also advantageous to arrange cooling elements between the friction rings, which are in particular welded or soldered onto the inside of the friction rings. Furthermore, the cooling elements can be screwed to the inside of the friction rings or soldered onto the end side. 
     The cooling elements increase the energy storing capacity of the brake disc. In the process, heat is directed from the friction ring into the cooling elements where it is discharged through convection. Thus, the convection surface is enlarged through the cooling elements, as a result of which more energy can be output to the flow medium. 
     In addition, the cooling elements can be configured so that these favour the cooling airflow through the shaft brake disc in that the cooling elements have for example a turbine blade-like shape. The cooling elements can be plate elements or alternatively or additionally a number of supporting pins can be arranged in addition to the cooling elements on the insides of the friction rings, but which have a length that is shorter than the supporting pins which extend between the two friction rings and connect these to one another. With the arrangement of the shortened supporting pins yet a further advantage is obtained to the effect that the arrangement of such shortened supporting pins can be effected for forming an optimal relationship of cooling capacity and dissipation and the geometry of the individual support pins can be selected with great freedom of design. 
     With additional advantage, the material of the cooling elements can be selected independently. Possible are steel and casting materials. In addition, however, non-ferrous metals such as aluminium or copper, or their alloys, can also be employed. The surface condition of the outer surface subjected to the incident flow can also be optimised with respect to thermal and flow-mechanical properties. 
     An inner row of supporting pins can be provided, which have axial passages, through which the connecting screws can extend. The connecting screws can for example be screwed into an internal thread, which is introduced into one of the friction rings, or screw nuts are provided, into which the connecting screws are screwed. In the case that the temperature loading is very high, the nut mounted onto the connecting screw on the end side can be formed as a sleeve and the thread decoupled from the temperature effect in this way. In addition, when using two sleeves installation space can be saved. Thus, the fastening ring, the friction rings and in particular the support bolts with the passages can be screwed together with full contact, as a result of which a particularly rigid connection between the friction rings and the hub is achieved. In this version, slot nuts are additionally employed. 
     On the hub, cams can be moulded on which, directed radially to the outside, extend between the friction rings and through which connecting screws are passed. Via the cams, the braking moment can thus be transmitted from the friction rings to the hub, wherein the cams can comprise recesses into which in turn slot nuts can be inserted, which can usually consist of hardened and tempered steel or cast iron. In particular, the slot nuts can have a minor radial mobility in the recesses of the cams in order to offset differences in the radial thermal expansion between the hub and the friction rings. 
     Furthermore, the friction rings can comprise protrusions facing radially to the inside, which can engage into recesses which are introduced in the hub. Thus a positive joint is achieved, in particular for transmitting the braking moments, which act from the friction rings on the hub. 
     Fastening rings can be provided, which on the outside contact the friction rings in the radial inner region. Here, connecting screws can extend through the fastening rings and at least through one part or a moulding of the hub, wherein in particular ceramic washers can be provided, which are arranged between the screw head of the connecting screws or between screw nuts on the connecting screws and the friction rings. Thus, a heat barrier is created, so that higher temperatures which can develop in the friction rings are not directly transmitted to the hub. The fastening rings additionally serve the purpose that the connecting screws cannot be subjected to bending distortion, wherein the fastening ring can be formed of a material which is characterized by a low expansion coefficient. Even by means of this a heat transfer from the friction rings to the hub can be minimised. 
     The positively-joined connection of friction rings and hub is suitable furthermore for a split version of the friction ring pair. To this end, the partition plane of the friction ring pair could be placed in the middle in the protrusions radially facing to the inside. Accordingly, a defined component of the centrifugal forces which act on the split friction ring pair could be transmitted to the hub via the cams. Accordingly, a possible partition screw connection of the two friction ring halves could be dimensioned smaller. 
     Finally, the use of a positively-joined connection makes possible the use of hub diameters which are larger compared with current connections. Since in this case the braking moment is transmitted via the positive joint of friction rings and hub, connecting elements, which in other embodiments transmit the braking moment, are omitted. Because of this, installation space can be saved which accordingly can be used for enlarging the hub diameter. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further measures improving the invention are shown in more detail in the following jointly with the description of preferred exemplary embodiments of the invention by means of the accompanying drawings, wherein: 
         FIG. 1  a perspectively shown detail of a shaft brake disc according to a first exemplary embodiment in a partly-mounted state, 
         FIG. 2  the exemplary embodiment of the shaft brake disc according to  FIG. 1  in a mounted state, 
         FIG. 3  the exemplary embodiment of the shaft brake disc according to  FIGS. 1 and 2  with a friction ring pair mounted to a hub in a transversely sectioned view, 
         FIG. 4  a perspective view of a friction ring of the exemplary embodiment of the shaft brake disc according to  FIGS. 1 to 3  for forming a friction ring pair, 
         FIG. 5  a perspective view of the hub of the exemplary embodiment of the shaft brake disc according to  FIGS. 1 to 4 , 
         FIG. 6  a perspectively shown detail of a shaft brake disc according to a second exemplary embodiment, 
         FIG. 7  the exemplary embodiment of the shaft brake disc according to  FIG. 6  with a friction ring pair mounted to a hub in a cross-sectioned view, 
         FIG. 8  a perspective view of a friction ring of the exemplary embodiment of the shaft brake disc according to  FIGS. 6 and 7  for forming a friction ring pair, 
         FIG. 9  a perspective view of the hub of the exemplary embodiment of the shaft brake disc according to  FIGS. 6 to 8 , 
         FIG. 10  a perspectively shown detail of a shaft brake disc according to a third exemplary embodiment, 
         FIG. 11  the exemplary embodiment of the shaft brake disc according to  FIG. 10  with a friction ring pair mounted on a hub in a cross-sectioned view, 
         FIG. 12  a perspective view of a friction ring pair of two friction rings of the exemplary embodiment of the shaft brake disc according to  FIGS. 10 and 11 , 
         FIG. 13  a perspective view of the hub of the exemplary embodiment of the shaft brake disc according to  FIGS. 10 to 12 , and 
         FIG. 14  a perspective view of a fastening ring with bolts arranged on the latter. 
     
    
    
     Same reference characters of different exemplary embodiments mark same functioned components with slightly different features. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  shows a detail of an exemplary embodiment of a shaft brake disc  1  according to the invention with a hub  10 , on which a first friction ring  11  and a second friction ring  12  arranged spaced from and parallel to the first friction ring  11  is arranged and which jointly form a friction ring pair. The shaft brake disc  1  can be employed in a brake system of a rail vehicle, and the friction rings  11  and  12  serve as friction partners for brake pads, which on the outside can be pressed onto the friction rings  11  and  12  with a brake caliper. Between the friction rings  11  and  12  multiple supporting pins (or bolts or dowels)  13  are arranged, which serve for absorbing the axially acting pad contact pressure forces  14  and prevent the deformation of the friction surfaces through static and dynamic screening. The friction rings  11  and  12  are produced from steel material and are cut out of a plate material through laser beam cutting or through water jet cutting. 
     The supporting pins  13  have a middle portion  13   a  and end-side pins  13   b  following the middle portion  13   a  on the end side. The end-side pins  13   b  can extend into the holes  15  in the friction rings  11  and  12  and for connection between the supporting pins  13  and the friction rings  11  and  12 , the end-side pins  13   b  can be soldered, welded, glued or pressed into the holes  15 . 
     The shown exemplary embodiment comprises supporting pins  13  with a middle portion  13   a , which has a smaller diameter than the end-side pins  13   b . The diameter jump allows a visual inspection of the same after application of a material joining method of the end-side pins  13   b  in the holes  15 . Furthermore, the pins  13   b  are longer than the thickness of the plates used in order to absorb tolerances of these plates. 
     Furthermore, a further row of supporting pins  13 ′ is shown, through which the connecting screws  17  are passed, and onto which end-side screw nuts  23  are screwed (detailed description see  FIG. 3 ). Additionally screwed with the connecting screws  17  and the screw nuts  23  is a fastening ring  21 , as a result of which the connecting screws  17  are not subjected to bending stress. 
     In the screw combination of the connecting screws  17 , sliding blocks  18  are additionally provided which are inserted into slots  31  and the slots  31  are located in protrusions  25 , which are moulded onto the hub  10 . The sliding block  18  is produced from hardened and tempered steel and only has a negligible influence on the heat conductance between the friction rings  11 ,  12  and the hub  10 . 
     In order to reduce a heat transfer between friction ring  11  and fastening ring  21 , ceramic washers  22  of ceramic or fibre-reinforced ceramic materials are located between friction ring  11  and fastening ring  21 . Alternatively, the fastening ring can be produced from steel which has a low heat expansion coefficient. 
       FIG. 2  shows a further perspective view of the shaft brake disc  1  with the hub  10  according to  FIG. 1 , wherein the inner row of supporting pins  13 ′ is shown, which are formed with axial passages  24 , through which the connecting screws  17  shown in  FIG. 1  can be passed. Here it is shown that the friction ring  11  comprises protrusions  19  facing radially to the inside, into which the supporting pins  13 ′ with the passages  24  project, so that a fixed connection between the supporting pins  13 ′ and the friction ring  11  can be created when the connecting screws  17  are passed through the axial passages  24 . A further row of supporting pins  13  shows an embodiment of the supporting pins  13  with a middle portion  13   a , which has a smaller diameter than the end-side pins  13   b  of the supporting pins  13 , which are connected to the friction rings  11  and  12 , wherein the friction ring  12  can have protrusions  19  in the same manner as the friction ring  11 , and the supporting pins  13 ′ extend with their opposite end into the protrusions  19  of the friction ring  19  which is not shown in more detail. 
       FIG. 3  shows the exemplary embodiment of the shaft brake disc  1  according to the  FIGS. 1 and 2  in a cross-sectioned view. The cross section shows the hub  10  with protrusions  25  radially directed to the outside, of which in the cross-sectional view a protrusion  25  is visible. On the protrusions  25 , the friction ring pair of the friction rings  11  and  12  is connected to the hub  10  in a torque-transmitting manner. For connecting the friction rings  11  and  12 , connecting screws  17  are provided, which extend through holes in the protrusions  25 . Furthermore, the connecting screws  17  extend through supporting pins  13 ′ with respective passages, and on the side located opposite the screw head of the connecting screw  17  screw nuts  23  are screwed onto the connecting screws  17 . Consequently, the protrusion  25 , the friction rings  11  and  12  as well as the supporting pins  13 ′ are screwed together “with full contact” by way of the connecting screws  17 . Below the screw nuts  23  is located a fastening ring  21 , wherein between the fastening ring  21  and the screw nuts  23  ceramic washers  22  are shown. Furthermore, supporting pins  13  are shown which extend between the friction rings  11  and  12 , and which are embodied solid without through-bore and extend with their end-side pin  13   b  into the holes  15  in the friction rings  11  and  12 . The shown arrangement advantageously makes possible a removal of the friction ring pair of the friction rings  11  and  12  with the supporting pins  13  from the hub  10  by simply loosening the connecting screws  17 . For example, an exchange of a warm friction ring pair can thus be performed in a simple manner and dependent on the installation situation of the shaft brake disc  1 , the hub  10  need not be removed from a shaft in order to replace the friction ring pair with the friction rings  11  and  12 . 
       FIG. 4  shows a friction ring  11  and  12  respectively in a perspective view. The friction ring  11  and  12  respectively can be cut out of a plate material of suitable thickness through a thermal cutting method, for example through laser beam cutting. With laser beam cutting, oxygen is suitable in particular as cutting gas. Likewise, an abrasive cutting method can be employed, for example water jet cutting. On the flat friction surface of the friction ring  11  and  12  respectively, holes  15  are shown into which the supporting pins  13  with their end-side pins  13   b  can be inserted. On the inside, the friction ring  11  and  12  respectively comprises protrusions  19  which radially face to the inside, in which through-bores  26  are introduced and through which the connecting screws  17  can be passed. The friction ring  11  and  12  respectively is placed on the hub  10  with a radial orientation, in which orientation the protrusions  19  of the friction rings  11 ,  12  are in alignment with the cams  25  of the hub  10 . 
       FIG. 5  finally shows a hub  10  in a perspective view, which comprises multiple protrusions  25  on its outer circumference. In the protrusions  25 , through-bores  27  are introduced through which the connecting screws  17  can extend and which are in alignment with the through-bores  26  in the friction rings  11  and  12  and with the axial passages  24  in the supporting bores  13 ′. In some of the protrusions  25 , slots  31  are introduced into which the sliding blocks  18  shown in  FIG. 1  can be inserted. 
       FIG. 6  shows a further exemplary embodiment of a shaft brake disc  1  with a hub  10 , which comprises cams  25  which are formed radially to the outside. The cams  25  comprise passages through which the connecting screws  17  are guided so that a connection with the friction ring  11  is created, through which the connecting screws  17  likewise extend. Below the heads of the connecting screws  17  in turn ceramic washers  22  are arranged, and in the cams  25  of the hub  10  milled slots  31  are introduced, into which the sliding blocks  18  are inserted. The slots  31  can also be milled into the friction surfaces. If the slots  31  are milled into the cams  25  of the hub  10  a tool is required which corresponds at least to half the height of the hub. In this exemplary embodiment, too, supporting bores  13  are shown which have a middle portion  13   a  with a smaller diameter and end-side pins  13   b  with a larger diameter, and the supporting pins  13  are connected to the friction rings  11  and  12  with the end-side pins  13   b.    
       FIG. 7  shows a cross-sectioned view through the shaft brake disc  1  according to the exemplary embodiment from  FIG. 6 . The shaft brake disc  1  comprises a friction ring pair of the friction rings  11  and  12 , which have supporting pins  13 , which extend between the friction rings  11  and  12 . In order to fasten the friction ring pair of the friction rings  11  and  12  to the hub  10 , the hub  10  comprises cams  25  which extend radially to the outside. Through the cams  25 , connecting screws  17  can be passed which extend equally through bores  36  in the friction rings  11  and  12 . When the screw nut  23  is screwed onto the free end of the connecting screw  17 , the friction rings  11  and  12  can be screwed to the cams  25  of the hub  10  “with full contact”, wherein the cams  25  are located between the friction rings  11  and  12 . In this exemplary embodiment, too, a ceramic washer  22  under the screw nut  23  is shown. If the friction ring pair of the friction rings  11  and  12  is to be removed from the hub  10 , the connecting screws  17  can be removed in order to subsequently easily turn the hub  10  relative to the friction ring pair. Thus, the cams  25  can be axially passed through the recesses  28  in order to remove the friction ring pair from the hub  10  without having to remove the two friction rings  11  and  12  from one another. 
       FIG. 8  represents a perspective view of the friction rings  11  and  12  respectively, in which a multitude of holes  15  for receiving the supporting pins  13  is introduced. The bores  36  in the friction rings  11  and  12  for passing through the connecting screws  17  are introduced in protrusions  19  radially facing to the inside, between which the recesses  28  extend. In some of the protrusions  19 , slots  31  for receiving sliding blocks  18  are milled, as already shown in  FIG. 6  in the assembled state. 
     Finally,  FIG. 9  shows a perspective view of the hub  10  according to the exemplary embodiment from  FIG. 6  with cams  25  projecting radially to the outside, into which through-bores  27  are introduced, through which the connecting screws  17  can be passed (see  FIG. 7 ). The through-bores  27  can be provided as through-bore for passing through simple connecting screws  17  with a threaded shank, and through the through-bores  30 , which correspond to the slots  31  introduced into the friction rings  11  and  12  for receiving the sliding blocks  18 , cylinder pins can be passed in order to create a corresponding tolerance dimension between the hub  10  and the friction ring pair and to transfer the fit to the friction ring pair via the sliding blocks  18 . The through-bores  30  for passing through the cylinder pins can for example have a larger diameter than the through-bores  27  for passing through simple connecting screws  17 . 
       FIG. 10  shows the hub  10  in a further embodiment of the shaft brake disc  1  with recesses  20 , into which the protrusions  19  of the friction rings  11  and  12  are inserted. The protrusions  19  face radially to the inside and the pocket-like recesses  20  enclose the protrusions  19  of the friction rings  11  and  12  (friction ring  12  is not shown in the perspective). Furthermore, supporting a pins  13  are shown which extend between the friction rings  11  and  12 . 
     A row of the pocket-like recesses  20  is closed in axial direction. Because of this, a degree of freedom of movement of the friction ring pair  11 ,  12  in an axial direction is blocked. For the complete axial fixing, a fastening ring  34 , see  FIG. 14 , with welded-on or soldered-on threaded pins  35 , which are passed through bores  36  in the protrusions  19  of the friction rings  11 ,  12  and the closed part of the hub  10 , is screwed against the back of the pocket-like recesses  20 . This ensures at the same time that upon breaking-out of a part of the friction ring  11 ,  12  the latter is locked through the threaded pin. 
     Alternatively, a flat fastening ring  21  can be directly screwed to the cams  25  of the hub  10 . As a thread safeguard, a self-locking thread or so-called screw lock threaded inserts can be used. 
     To axially secure the friction rings  11  and  12 , fastening rings  21  are shown, which are exemplarily embodied with axial protrusions  32 , and through holes  33  in the fastening rings  21  screw elements can be passed in order to screw the fastening rings  21  to one another. Here, the axial protrusions  32  of the fastening rings  21  can be axially pressed onto one another or by screwing the fastening rings  21  together the latter can be at least axially clamped to one another. Thus, the friction rings  11  and  12  are axially locked and the torque of the friction rings  11  and  12  can be transmitted to the hub  10  via the protrusions  19  in the recesses  20 . 
       FIG. 11  shows the exemplary embodiment of the shaft brake disc  1  according to  FIG. 10  in a cross-sectioned view. Shown is the connection between the hub  10  and the friction ring pair of the friction ring  11  and  12 , between which the supporting pins  13  extend. The hub  10  comprises cams  25 , into which holes  33  are introduced. Through holes  33  in one of the friction rings  12  and through the holes  33  in the cams  25  on the hub  10 , threaded pins  35  can be passed which are located on a fastening ring  34 . At the end side on the threaded bolts  35 , screw nuts  23  are screwed on in order to connect the friction ring pair to the hub  10  via one of the friction rings  12 . 
       FIG. 12  shows the friction ring pair of the friction rings  11  and  12 , wherein in the lower friction ring  12  bores  29  are introduced through which the threaded pins  35  of the fastening ring  34  can be passed. The bores  29  are introduced into protrusions  19  in the friction ring  12  which radially extend to the inside. The protrusions  19  of the friction ring  11  are offset with respect to the protrusions  19  of the friction ring  12  by an angle of for example 30°, so that accessibility of the screw nut  23  is ensured, see  FIG. 11  in this respect. 
       FIG. 13  perspectively constitutes a hub  10  according to the exemplary embodiment from  FIG. 10 . On the hub  10 , multiple cams  25  radially extend to the outside, which partly have axial protrusions  32 , between which intermediate spaces are formed, into which the protrusions  19  of the friction rings  11  and  12  can engage. Thus, the braking moment can be transmitted between the cams  25  and the protrusions  19  via the positively joined connection and the screw connection of the friction ring  12  to the hub  10  via the threaded pins  35  of the fastening ring  34  merely serves to axially secure the friction ring pair on the hub  10 . Additionally shown are holes  33  in the cams  25 , through which the threaded pins  35  of the fastening ring  34  can be passed. 
       FIG. 14  finally shows a perspective view of the fastening ring  34  with multiple threaded pins  35  axially located on said fastening ring  34 . Thus, the use of the fastening ring  34  with respect to the fastening ring  21  in  FIG. 10  constitutes a further alternative for connecting the friction ring pair to the hub  10 . 
     In its embodiment, the invention is not restricted to the preferred exemplary embodiment stated above. A number of variants is rather conceivable which makes use of the shown solution even with fundamentally different types of embodiments. All features and/or advantages arising from the claims, the description or the drawings including design details or spatial arrangements can be substantial to the invention both by themselves as well as in a wide range of combinations.