Abstract:
The present invention relates to a multi-disc clutch for the transfer of torque between a first clutch part and a second clutch part, having at least one first and at least one second disc that engage on another and that are movable parallel to a rotational axis of the multi-disc clutch, and having a reset device for the receiprocal ventilation of adjacent discs. The first clutch part is connected in a rotationally secure fashion to the first disc and the second clutch part is connected in a rotationally secure fashion to the second disc. The reset device has at least two reset elements that are disposed eccentrically relative to the rotational axis and distributed in the circumferential direction.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. application Ser. No. 12/786,567 filed May 25, 2010 which claims priority to German Application No. 10 2009 022 668.0 filed May 26, 2009. The entire disclosure of each of the above-noted applications is incorporated herein by reference. 
     
    
     FIELD 
       [0002]    The present invention relates to a multi-disc clutch for the transfer of torque between a first clutch part and a second clutch part. 
       BACKGROUND 
       [0003]    Multi-disc clutches of this type see widespread use, especially in motor vehicles. For example, multi-disc clutches are used in transfer cases, which are used in all-wheel drive vehicles for distributing torque onto the individual vehicle axles. As a rule, multi-disc clutches have inner and outer discs engaging with one another that are connected to an inner part of the clutch (e.g., the input shaft) or an outer part (e.g., the clutch cage). In order to be able to connect the shaft and the clutch cage in a driven manner, the discs are placed in a frictional engagement with one another. Such a multi-disc clutch is disclosed in DE 10 2006 034, 153 A1. It includes a clutch hub that produces a rotationally secure connection between the inner discs of the clutch and the input shaft. A return device for the clutch is also disposed in the hub in order to be able to reliably separate the inner and outer discs from one another (“ventilation”) and reduce drag torque when separating the clutch. Multi-disc clutches of this kind are generally wet running, i.e., the discs are lubricated and cooled using oil. 
         [0004]    Although multi-disc clutches of this type are very reliable, clutches are needed that are more cost effective and that are not inferior in any way to the known clutches, in particular with regard to their dynamics and ability to transfer torque. 
       SUMMARY OF THE INVENTION 
       [0005]    The object of the present invention is therefore to create a multi-disc clutch that is cost-effective to produce and that allows the transfer of high torques while at the same time having a high degree of dynamics. 
         [0006]    The multi-disc clutch according to the invention for the transfer of torque between a first clutch part and a second clutch part, for example, a shaft and a clutch cage, has at least one first disc and at least one second disc, which engage in one another and are movable parallel to a rotational axis of the multi-disc clutch. Moreover, a reset device is provided for the reciprocal release of neighboring discs. The first clutch part is connected to the first disc (for example, an inner disc) in a rotationally secure fashion, and the second clutch part is connected to the second disc (for example, an outer disc) in a rotationally secure fashion. Any desired number of discs may be provided. 
         [0007]    The multi-disc clutch is characterized in that the reset device has at least two reset elements that are eccentrically disposed relative to the rotational axis and distributed in the circumferential direction. In particular, the reset elements are evenly distributed in the circumferential direction. In certain applications, an uneven distribution of the reset elements—not only in the circumferential direction, but also in the radial direction—may also be advantageous. 
         [0008]    Known multi-disc clutches have at least one reset device that is disposed coaxially to a shaft, i.e., surrounds the shaft in the circumferential direction. Such a reset device is, for example, a compression spring that coaxially surrounds the shaft. As already mentioned above in conjunction with the known multi-disc clutches, a clutch hub accommodates the reset device in such cases. This structural principle is not used according to the invention; rather, the reset device has a plurality of reset elements that are offset radially outward, i.e., are not disposed coaxially to the rotational axis. The reset elements are distributed in the circumferential direction in order to generate a reset force at various points, which allows a reliable ventilation of the discs. In particular, the reset elements lie on a common circle whose center point coincides with the rotational axis of the multi-disc clutch. 
         [0009]    The spatial orientation of the reset elements in their eccentric position relative to the shaft—i.e., for example, whether they are disposed with their longitudinal extension parallel or slightly oblique to the shaft—may be adapted to the particular requirements in each case. 
         [0010]    The construction according to the invention allows the hub, which has been used up to now, to be omitted or at least to have a substantially simpler structure. This reduces the production costs and allows for a more compact configuration. 
         [0011]    The first disc preferably has at least one respective recess through which at least one of the reset elements extends in the axial direction. The reset elements thus extend partially through the stack of discs formed by the at least one first disc and at least one second disc. 
         [0012]    The reset elements may be disposed radially inside the second disc relative to the rotational axis. In other words, the reset elements are disposed inside the inner diameter of the second disc in the radial direction. For example, a plurality of first and second discs are provided, with the first discs being inner discs and the second discs being outer discs. In this case, the inner circumference of the outer discs is disposed farther outward radially than the reset elements. In this arrangement, when the multi-disc clutch is activated, the connection between the first and the second discs is created radially outside of the reset elements in order to allow for the transfer of the greatest possible amount of torque. 
         [0013]    The first clutch part may be a shaft or a coupling sleeve connected to a shaft in a rotationally secure manner, with the first disc/s extending in the radial direction essentially to the shaft. In other words, a coupling sleeve is to be understood as a simple component that particularly serves to simplify installation, but does not have any substantial radial extension in its own right. The first disc/s should therefore be connected in a rotationally secure fashion to the shaft, either directly or indirectly, via the sleeve mentioned above. In the case of an indirect connection, it is preferable for the inner circumference of the disc to essentially correspond to the outer circumference of the shaft, i.e., for the sleeve to be relatively thin and, in particular, not to house any additional structural or functional components. The rotationally secure connection may be formed using a spline, for example. 
         [0014]    It is preferable for the shaft to be a through drive of a transfer case, with the shaft simultaneously forming an input shaft and a first output shaft, and with the transfer case having a second output shaft, as is described in DE 10 2006 034, 153 A1, which was mentioned at the outset. However, the transfer case may also be embodied as an interaxle differential transmission. In such a case, the shaft is not a through drive, but rather, for example, a driven shaft of the transfer case, and the multi-disc clutch serves as a locking clutch in this case. 
         [0015]    According to one embodiment of the multi-disc clutch, a retaining device is provided for securing the reset elements in the radial direction of the multi-disc clutch. The retaining device thus counteracts the centrifugal forces that occur during operation of the clutch and secures the position of the reset elements in order to allow a reliable ventilation of the clutch in all operating states. 
         [0016]    An advantageous development of the retaining device includes a pin extending in the axial direction for each reset element that carries the respective reset element. In particular, the pin is supported in the axial direction on a first component of the clutch and is disposed in an axially movable fashion relative to a second component of the clutch. The components mentioned above are disposed in a rotationally secure fashion relative to one another on sides of the disc stack that are axially opposite one another. The second component may be, for example, an axially movable pressure disc (pressure piston) for activating the clutch. The first component may be, for example, an axially fixed counterpressure disc against which the stack of discs is pressed when the clutch is activated. With regard to the axial support of the pin, it should be mentioned that the support may be direct or indirect, with an indirect support being understood as an interposition of one or more components. 
         [0017]    According to an additional embodiment, a distributor insert having at least one conduit-like extension extending in the axial direction of the multi-disc clutch is provided in the radial inner chamber of the multi-disc clutch for distributing lubricant. In particular, an extension is assigned to at least one of the reset elements, with the extension at least partially surrounding the reset element in the circumferential direction. It is also possible for such an extension to be assigned to each of the reset elements. The extension may have at least one opening on its circumferential surface through which the lubricant is able to escape in the radial direction. In other words, the lubrication of the multi-disc clutch is ensured in a simple fashion by the distributor insert. The conduit-like extensions—regardless of their cross section—are provided for this purpose. Lubricant may be supplied and distributed through these extensions in the axial direction. 
         [0018]    It has been proven advantageous for the distributor insert to form a lubricant chamber that is connected to the at least one extension and is disposed at an offset in the axial direction relative to the discs. In this embodiment, the lubricant chamber is disposed on one of the two sides of the disc stack, i.e., it is not disposed in the radial direction between an input shaft and the disc stack of the clutch, for example. The lubricant chamber particularly serves as an intermediate reservoir that is supplied with lubricant from outside the clutch and that “relays” the lubricant to the at least one extension. The lubricant chamber may be formed completely or partially by the distributor insert. “Partially” means that the distributor insert is combined with one or more other components of the multi-disc clutch to form the lubricant chamber. 
         [0019]    The distributor insert may include an annular plate that extends essentially in a plane that is perpendicular to the rotational axis and that is connected to the extension, in particular, that is designed as one piece with the extension. The annular plate may have an edge section extending in the axial direction on its outer circumference in order to form a lubricant chamber with a component of the multi-disc clutch. For example, one component of the clutch forms one or more side walls of the lubricant chamber. The other side walls are then formed by the annular plate and the edge section. 
         [0020]    The lubricant chamber is preferably connected to a lubricant conduit through which lubricant may be supplied to the lubricant chamber, with the lubricant conduit having an oil supply device. In particular, the oil supply device is an annular element that is rotationally mounted and conically formed in the axial direction, for example, a frustoconical ring (truncated cone) that forms a centrifugal disc. “Supply” is also to be understood as supporting the distribution of lubricant. 
         [0021]    According to another embodiment of the multi-disc clutch, a retaining device is provided for the purpose of securing the reset elements in the radial direction of the multi-disc clutch, with the retaining device having two fastening devices for each reset element that are formed on different components of the clutch that are disposed in a rotationally secure fashion relative to one another (for example, on a pressure plate and a counterpressure plate), with the components being disposed on axially opposite ends of the disc stack formed by the first and second discs. This embodiment of the retaining device may be realized in a particularly simple fashion and nevertheless allows a reliable fastening of the reset elements. 
         [0022]    Recesses or pins may be considered as suitable fastening devices. These fastening devices may also be used in any desired combination in order to create a reliable retaining device. 
         [0023]    For reasons of simplified installation, it is advantageous for the distributor insert and the retaining device to form one structural unit, which is designed in particular as one piece. The distributor insert and/or the retaining device may be essentially made of plastic, whereby the production costs for the multi-disc clutch are reduced. 
         [0024]    An additional simplification of the embodiments of the multi-disc clutch according to the invention having a distributor insert and/or a retaining device is achieved if the distribution insert and/or the retaining device are attached in a rotationally secure fashion to a component that is movable in the axial direction for the purpose of activating the clutch. Such a component that is movable in the axial direction is, for example, the pressure plate, which has been discussed multiple times. This fastening may occur by snapping into place, for example. 
         [0025]    Advantageous reset elements have elastic properties. Coil springs, in particular embodied as compression springs, are suitable for this purpose. 
         [0026]    The invention further relates to a transfer case having a multi-disc clutch according to one of the embodiments described above. As has already been discussed above, a transfer case should particularly be understood to mean a transmission having one input shaft and two output shafts (with a through drive or a differential). 
         [0027]    Additional embodiments of the invention are provided in the description, the drawings, and the claims. 
     
    
     
       DRAWINGS 
         [0028]    The present invention will be described below purely by way of example with reference to advantageous embodiments. Shown are: 
           [0029]      FIG. 1  is a schematic cross section of an embodiment of the multi-disc clutch according to the invention; 
           [0030]      FIG. 2  is a cross section of an additional embodiment of the multi-disc clutch according to the invention; 
           [0031]      FIG. 3  is a perspective view of the embodiment according to  FIG. 2 ; 
           [0032]      FIG. 4  the view according to  FIG. 3  with an inner disc; 
           [0033]      FIG. 5A  is a schematic cross section of another embodiment of the multi-disc clutch according to the invention; 
           [0034]      FIG. 5B  is an enlarged section of  FIG. 5A ; 
           [0035]      FIGS. 6A and 6B  are various embodiments of a retaining device; and 
           [0036]      FIGS. 7A and 7B  are exploded views of another embodiment of a multi-disc clutch according to the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0037]      FIG. 1  schematically shows a cross section of a multi-disc clutch  10 . The multi-disc clutch  10  is used to transfer torque between a shaft  12  that is driven to a rotational motion around a rotational axis R and a clutch cage  14  that is rotationally mounted relative to the shaft  12  and that is connected in a driven fashion to additional elements of a transfer case (not shown). The multi-disc clutch  10  has inner discs  16  that are connected in a rotationally secure fashion to the shaft  12  by a gearing. The inner discs  16  are displaceable in the axial direction, i.e., parallel to the rotational axis R. Analogously, the outer discs  18  are associated with the clutch cage  14 . 
         [0038]    In order to transfer torque from the shaft  12  to the clutch cage  14 —in certain applications, the transfer of torque may occur in the reverse direction as well—a partial or complete connection must be produced between the inner discs  16  and the outer discs  18 . This occurs by an axial displacement of the discs  16 ,  18  in order to bring them into frictional engagement with one another. The strength of this connection depends on the axial force exerted for the axial displacement. The discs  16 ,  18  may be provided with friction elements in order to improve the frictional engagement. 
         [0039]    The axial force described above for activating the clutch is provided by a pressure piston  20 . The pressure piston  20  may be displaced in the axial direction. A displacement of the pressure piston  20  is achieved using a ball ramp unit  22  that is connected to the pressure piston  20  via an axial bearing  24 . If the ramp rings  22   a ,  22   b  of the ball ramp unit  22  are twisted opposite one another, then they move apart due to the inclined ramps formed in said ramp rings in conjunction with the balls  22   c  disposed between the ramp rings  22   a ,  22   b . Because the ramp ring  22   a  is supported in the axial direction on an axial bearing  24 ′, this results in a movement of the ramp ring  22   b  to the left, whereby the pressure piston  20  compresses the disc stack formed by the inner discs  16  and the outer discs  18 . The disc stack is supported in the axial direction on a counterpressure plate  26 , which is connected to the shaft  12  in a rotationally and axially fixed fashion. 
         [0040]    When the activation of the clutch is removed, i.e., the clutch is released, the pressure piston  20  may be moved to the right again. However, this occurs only if a corresponding reset force is provided. This reset force causes the clutch to open, i.e., the discs  16 ,  18  are able to separate again, whereby the frictional engagement is removed (“ventilation of the clutch”). 
         [0041]    The reset force is provided by a reset device.  FIG. 1  shows a spring  28  that, as a reset element, is a part of the reset device. The spring  28  acts between the pressure piston  20  and the counterpressure plate  26 . Upon activation of the clutch  10 , the spring  28  is compressed. The force thus applied is converted back into a movement of the pressure piston  20  to the right upon the activation of the clutch being terminated. In contrast to the known reset device concepts, the spring  28  is disposed in an eccentric fashion, i.e., is not coaxial to the shaft  12 . Therefore, it does not act on the pressure plate  20  in a region in the vicinity of the shaft; rather, it acts in a central area—viewed in the radial direction—which has an advantageous effect on the reset or ventilation process. 
         [0042]    In order to secure the spring  28  in its position, a pin  30  is provided that extends through the spring  28 . Thus, the spring  28  may be radially supported on the pin  30  if centrifugal forces are acting on the spring  28  during operation of the clutch  10 . The pin  30  is formed on a distributor insert  32  that simultaneously ensures the supply of lubricant oil to the multi-disc clutch  10  and the distribution of lubricant in its interior. A conduit  34  located radially to the outside is associated with the pin  30  and the spring  28 , through which the lubricant may be supplied in the axial direction through the disc stack. The interior of the conduit  34  is connected to a lubricant chamber  36  located radially to the inside that is supplied with lubricant via a lubricant conduit  38 . The lubricant conduit  38  has a lubricant conduit section  381  that is disposed in a rotationally secure fashion relative to a multi-disc clutch housing (not shown). The lubricant escaping from the conduit section  38 ′ is transferred to a lubricant conduit section  38 ″ that is in contact with the rotating elements of the multi-disc clutch  10 . In the embodiment shown in  FIG. 1 , these rotating components are the shaft  12  on one side and a centrifugal disc  40  on the other side, which is a conically shaped ring or conically shaped pipe section that opens in the direction of the disc stack. 
         [0043]    The lubricant is carried along by the rotation of the shaft  12  and the centrifugal disc  40  and conveyed to the lubricant chamber  36 . The centrifugal force caused by the rotation pushes the lubricant radially outwards, and therefore also into the conduit  34 , where it is further conveyed in the axial direction. The lubricant is distributed between the discs  16 , 18  through openings (not shown) in the radially outer wall of the axial conduit  34 . In principle, corresponding openings may also be provided on the radially inner wall of the conduit  34 . 
         [0044]      FIG. 1  shows that the conduit  34  does not extend completely through the disc stack in the region of the counterpressure plate  26 . The gap between the conduit  34  and the counterpressure plate  26  is closed; however, when the pressure piston  20  also presses the distributor insert  32  to the left upon activation of the clutch  10 . In order to allow an axial motion of the distributor insert  32  relative to the counterpressure plate  26 , the pin  30  is also mounted on the counterpressure plate  26  in an axially movable fashion. For this purpose, a bore  42  is provided in the counterpressure plate  26 . On the side of the pressure piston, the spring  28  is supported on the pressure piston  20  in an axially secure fashion via a base section  44  of the distributor insert  32 . 
         [0045]    In order to divide the lubricant chamber  36  from the disc stack in a region near the shaft, the distributor insert  32  has an annular plate  46 . 
         [0046]      FIG. 1  shows only a single spring  28  with a conduit  34  surrounding it. In practice, however, the multi-disc clutch  10  has two or more resetting springs  28  and conduits  34 , which are evenly distributed in the circumferential direction. Here, provision may be made for a conduit  34  to be allocated to each spring  28 . In certain applications, however, it is advantageous for not every spring  28  to have a conduit  34  allocated to it, but rather, for example, only every other spring. Conversely, it is also conceivable for more conduits  34  to be provided than springs  28 . 
         [0047]    The distributor insert  32  may be produced in a cost-effective manner as a one-piece component made of plastic that ensures a distribution of lubricant in the interior of the clutch  10  as well as carrying the components of the reset device in the form of the springs  28 . In order to simplify installation, the distributor insert may be fastened to the pressure plate  20  with the aid of locking levers  48 . 
         [0048]      FIG. 2  shows another embodiment of the multi-disc clutch  10 ; for the sake of clarity, the shaft  12 , the disc stack, and the clutch cage  14  are not shown here. Components with the same function as in the embodiment described above are designated with the same reference characters. 
         [0049]    Among other things, the figure shows the lubricant conduit section  38 ′, which is fixed to the housing, having a connector piece  38   a  for connection to a lubricant supply and the centrifugal disc  40 , which form the lubricant conduit  38  along with the shaft  12 , which is not shown. Components of the ball ramp unit  22 , which is responsible for an axial movement of the pressure piston  20 , may also be seen. The ramp ring  22   b  has a gear wheel  50 . Using the gear wheel  50 , the ramp ring  22   b  may be twisted relative to the ramp ring  22   a , thus activating the clutch  10 . 
         [0050]    In addition, the structure of the distributor insert  32 , which is locked onto the pressure piston  20 , may be seen. The embodiment shown has six conduits  34 , which are evenly distributed in the circumferential direction and of which only three may be seen in the view shown in a sectional plane along the rotational axis R of the multi-disc clutch  10 . The conduits  34  surround the springs  28  allocated to them, which are disposed on pins  30 . The distributor insert  32  is connected in a rotationally secure manner to the pressure piston  20 , which in turn is connected in a rotationally secure manner to the shaft  12  (not shown) via a gearing  52 . 
         [0051]      FIG. 2  also clarifies the structure of the lubricant chamber  36 , which is connected to each of the conduits  34  and is limited in the axial direction by the annular plate  46 . The axially opposite wall of the lubricant chamber  36  is formed by the pressure piston  20 . The lubricant is prevented from escaping from the lubricant chamber  36  in the radial direction by a side wall section  54  formed on the distributor insert  32 . 
         [0052]      FIG. 3  shows a perspective view of the embodiment according to  FIG. 2  for the purpose of clarifying the spatial arrangement of the components described here. 
         [0053]      FIG. 4  is based on the view of  FIG. 3 , however, an inner disc  16  has been added in order to describe the structure and functionality of the inner disc  16 . The inner disc  16  is connected in a rotationally secure manner to the shaft  12 , which is not shown, by a gearing  52 ′. In contrast, an axial displacement of the inner disc  16  is possible, as was already described at the outset. The inner disc  16  has recesses  55  that are circumferentially closed and through which the conduits  34  of the distributor insert  32  extend. The springs  28  thus penetrate the inner disc  16  (and the other inner discs, which are not shown here). Moreover, the inner disc  16  is provided in a radially outer region with frictional coverings  56  that cooperate with the corresponding frictional coverings of an adjacent outer disc  18 , which is not shown, upon activation of the multi-disc clutch  10 . The region provided with the frictional coverings  56  approximately corresponds to the region that is subjected to an axial force upon activation of the multi-disc clutch  10  by the pressure piston  20 . The outer discs  18  do not extend substantially farther inward in the radial direction than the region of the inner discs  16  defined by the frictional coatings  56 . On the one hand, a connection of the discs  16 , 18  is desired that is located as far to the outside as possible in order to be able to transfer large amounts of torque and, on the other hand, the outer discs  18  cannot extend substantially farther inward because otherwise the conduits  34  would block a rotation between the discs  16 , 18 . 
         [0054]    In the embodiment shown, the conduits  34  do not have any openings on their outsides. However, such openings may be provided in order to provide the clutch  10  with lubricant in various axial sections of the disc stack. 
         [0055]    Another embodiment of the multi-disc clutch  10  is shown in  FIG. 5A . Components with a corresponding function to those in the embodiment described above have been designated with the same reference characters. 
         [0056]    The essential difference between the two embodiments lies in the fact that the springs  28  of the embodiment according to  FIG. 5A  are not mounted on an axial pin  30 . In order to secure the springs  28 , recesses  58  and  58 ′ are provided on the counter-pressure plate  26  and the pressure piston  20 , into which the respective ends of the springs  28  are inserted. With its simple construction, this embodiment does not require any additional structural components to take into account the relative axial motion of the counterpressure plate  26  and the pressure piston  20 . 
         [0057]      FIG. 5B  shows an enlarged section of  FIG. 5A  in order to clarify the structure of the recesses  58 ,  58 ′ and the spring  28  disposed therein. Moreover, the dashed arrows show the course of a lubricant SF through the distributor insert  32  into the disc stack. The conduit  34  shown in  FIG. 5B  has radial openings  60  for the purpose of distributing the lubricant to different axial regions of the disc stack. The lubricant flow SF through the lubricant conduit  38  into the lubricant chamber  36  is shown in  FIG. 5A . 
         [0058]      FIG. 6A  clarifies again schematically how the recesses  58 ,  58 ′ are disposed for securing the spring  28 .  FIG. 6B  shows an alternative embodiment in which, instead of the recesses  58 ,  58 ′, pins  58   a ,  58   a * are provided for the purpose of holding the spring  28  in its position. It is to be understood that combinations of the two variants shown are also possible. In one combination, for example, the spring  28  may be disposed on one side in the recess  58  or  58 ′ while the spring is secured on the other side by the pin  58   a  or  58   a ′. The spring is secured in a particularly reliable fashion if recesses  58 ,  58 ′ as well as pins  58   a ,  58   a ′ are provided, i.e., if the pin  58   a  or  58   a ′ is additionally provided in the central region of the recess  58  or  58 ′, in order to secure the spring  28  from “inside” and from “outside” against changes in position. 
         [0059]      FIGS. 7A and 7B  show an exploded view of an embodiment that, like the embodiment according to  FIGS. 5A and 5B , does not have any axial pins  30  for securing the springs  28 . The one-piece construction of the distributor insert  32  as well as the recesses  58 ,  58 ′ on the counterpressure plate  26  and the pressure piston  20  may be clearly seen. Moreover, locking levers  48 ′ are shown on the centrifugal disc  40 , which contribute to a rotationally secure attachment of the centrifugal disc  40  to the pressure plate  20 . A relative twisting of the centrifugal disc  40  and the pressure plate  20  is also prevented by recesses  62  on the centrifugal disc  40  that cooperate with gear segments  52  on the pressure plate  20 . 
       LIST OF REFERENCE NUMBERS 
       [0000]    
       
         
           
               10  Multi-disc clutch 
               12  Shaft 
               14  Clutch cage 
               16  Inner disc 
               18  Outer disc 
               20  Pressure piston 
               22  Ball ramp unit 
               22   a ,  22   b  Ramp ring 
               22   c  Ball 
               24 ,  24 ′ Axial bearing 
               26  Counterpressure plate 
               28  Spring 
               30  Pin 
               32  Distributor insert 
               34  Conduit 
               36  Lubricant chamber 
               38  Lubricant conduit 
               38 ′ Lubricant conduit section, fixed 
               38 ″ Lubricant conduit section, rotating 
               38   a  Connector piece 
               40  Centrifugal disc 
               42  Bore 
               44  Base section 
               46  Annular plate 
               48 ,  48 ′ Locking lever 
               50  Gear wheel 
               52 ,  52 ′ Gearing 
               54  Side wall section 
               55  Recess 
               56  Fictional covering 
               58 ,  58 ′,  58   a ,  58   a ′ Recess 
               60  Opening 
               62  Centrifugal plate recess 
             R Rotational axis 
             SF Lubricant flow