Abstract:
A coupling assembly which has an adjusting device. In order to prevent uncontrolled adjusting of the adjusting device during transport until installation, a transport lock is provided. In order to be able to further propose an installation space-neutral solution, which, in particular, has no negative impact on the actuating system, grabber arms are disposed for lever elements of the coupling assembly axially in the direction of the counterpressure plate.

Description:
This application is a continuation of PCT/DE2009/001431 filed Oct. 12, 2009, which in turn claims the priority of DE 10 2008 054 326.8 filed Nov. 3, 2008 and DE 10 2008 059 304.4 filed Nov. 27, 2008, the priority of these applications is hereby claimed and these applications are incorporated by reference herein. 
    
    
     FIELD OF THE INVENTION 
     The invention relates to a clutch unit having a transport lock which acts in the non-installed state. 
     BACKGROUND OF THE INVENTION 
     Clutch units are used in particular in drivetrains of motor vehicles between an internal combustion engine and a transmission. Depending on the design of the transmission, a provision may be made for a single friction clutch to couple the crankshaft to a transmission input shaft, or a multiple clutch, such as a double clutch with two friction clutches, to distribute torque to two transmission input shafts or to a transmission input shaft and an auxiliary drive output in the clutch unit. Here, at least one friction clutch has an adjusting device which in particular compensates for the wear of the friction linings of the clutch disk connected to the associated transmission input shaft for conjoint rotation therewith, this being achieved by virtue of a ramp device being provided between the pressure plate and lever elements which apply load to the latter, which ramp device compensates for the incorrect spacing resulting from wear. Here, the initiation of an adjusting process by rotating the ramp device is determined by sensor devices which measure a travel or an actuating force of the lever elements. Such adjusting devices are known from documents DE 42 39 291 A1, DE 42 39 289 A1, DE 43 22 677 A1 and DE 44 31 641 A1. 
     To prevent an uncontrolled adjustment of such adjusting devices in particular of so-called pushed-closed friction clutches, which are open when not subjected to load by the actuating system and are closed by the application of load to the lever tips of the lever elements, it is possible to use transport locks which fix the lever elements axially in a position which prevents a complete relaxation of the lever elements. Such transport locks may for example be formed from components such as rings which are fixedly connected to the housing of the clutch unit and which prevent the lever tips from pivoting out axially. As a result of the necessary arrangement of said components, the installation space available for the actuating system which engages in said region is limited. Simpler designs provide separable or spring-loaded transport locks which act only once and are no longer available after being dismounted. 
     SUMMARY OF THE INVENTION 
     It is therefore the object to propose a clutch unit with an adjusting device in which the adjusting device is protected against an uncontrolled adjustment by means of a transport lock which can be provided without taking up any further installation space in relation to the actuating system. Furthermore, a transport lock of said type should remain effective over multiple installation and removal processes of the clutch unit. 
     The object is achieved by means of a clutch unit having at least one friction clutch, comprising at least one pressure plate which is connected to a housing for conjoint rotation therewith but so as to be axially movable to a limited extent, it being possible for the housing to be connected to a counterpressure plate, and with lever elements provided in an annular arrangement being arranged between the housing and pressure plate, which lever elements are pivotably supported on a rolling support which is borne by the housing and which can be adjusted axially by an adjusting device for the compensation of wear, and which lever elements can be subjected to load at their radially inner lever tips in order to close the friction clutch, wherein the lever tips are secured axially, in a non-installed state, by a transport lock, and the lever tips are secured axially by means of catch arms which are aligned axially in the direction of the counterpressure plate and which engage axially behind and are supported on the rear side of the housing. 
     The lever elements, which are arranged outside the housing, are clamped in a predefined position in relation to the housing arranged axially within by means of the transport lock, which position prevents a complete relaxation of the lever elements and therefore an uncontrolled adjustment of the friction clutch comprising the lever elements, but is more relaxed than an end position of the lever tips of the lever elements permitted by the actuating system. In this way, in the normal operating state of the friction clutch, the lever tips do not reach the stop state at which the lever tips are delimited axially by the transport lock. 
     If the clutch unit is dismounted again, the action of the transport lock takes effect again and, in this state, too, prevents an uncontrolled adjustment, such that the clutch unit can for example be assessed in the state which it was in before being dismounted, and can be used again effectively after an exchange of the clutch disk with possibly worn friction linings. 
     As a result of the arrangement of the transport lock with components which extend only within the installation space of the clutch unit even during operation in the installed state, the installation space outside the installation space of the clutch unit can be provided entirely for the actuating system. This is particularly advantageous if a plurality of, for example more than two, friction clutches are arranged in the clutch unit, the lever elements of which are subjected to load by two mutually separately operating actuating systems. 
     In an advantageous exemplary embodiment, the catch arms may be held at one end on the lever tips and supported at a free end on the rear side of the housing by means of a catch hook. To be able to leave the inner circumference of the housing free in an undisrupted manner even under restricted installation space conditions, the catch arms for forming the axial stop by means of the catch hook which engages behind the housing are preferably guided in openings which are radially spaced apart from the inner circumference. Here, a profile of the openings is designed such that the catch hooks form an axial stop on the openings, that is to say cannot pass through the openings. 
     To insert the catch arms with catch hooks which extend beyond the openings and which engage behind the housing, slots which form a widening in the radial direction on the inner circumference of the housing and which connect the inner circumference and the respective opening may be provided, via which slots the catch arms are inserted into the openings. For this purpose, an advantageous assembly method makes provision for the catch arms, in order to form the catch hooks, to be provided at their free end with a larger area in the circumferential direction than the openings. Thereafter, during an axial movement of the lever elements for the positioning thereof on the housing, the catch arms attached to the lever elements bear under radial preload against the inner circumference. As a result of the axial movement of the lever elements, firstly the catch hooks slide past the slots until the catch arms, as a result of the smaller dimension of the catch arms, snap into the slots and subsequently into the openings. 
     Here, it has proven to be advantageous for the catch arms to be attached at a radial distance from a contact surface of the actuating bearing, wherein during the insertion of the catch arms during the mounting for example of a lever spring with the lever elements, the catch arms are at least partially plastically deformed on the inner circumference of the housing and thereby calibrated, such that they spring elastically into the openings to a predefined extent. 
     In a further exemplary embodiment, the catch arms may be formed with the same profile throughout, for example from sheet metal with a rectangular profile, wherein the openings are matched in a complementary manner to said profile and, after the catch arms are passed through the openings, the free end of the longitudinal axis of the catch arms is twisted, such that the catch hooks thereby formed form an undercut in relation to the openings. 
     To form the transport lock, a plurality of catch arms distributed over the circumference may be held, for example riveted to, individual lever elements. Here, lever elements adjacent to one another may have a corresponding spacing to one another or may be cut out in such a way that the respective catch arm can be guided therebetween in an axially undisrupted manner to the opening. 
     The catch arms have, at their ends situated opposite the catch hooks, a head part by means of which the catch arms are connected, for example riveted, to the corresponding lever element. Here, the head parts may be arranged on both sides of the lever elements. It has proven to be particularly advantageous for the head parts to be attached to that side of the lever elements which faces away from the housing on which the catch hooks are supported, such that the entire surface of the head part can be supported on the lever element and therefore the diameter of the rivet head, which serves as a support surface of the respective catch arm during the housing-facing fastening of the head part, of riveted catch arms is insignificant. In this way, the catch arms can, for the same material loading of the lever element by the opening for riveting, be arranged radially further inward. 
     According to the concept of the invention, provision is made for a reliable deflection of the catch arms into the openings provided for this purpose in the housing to be ensured even when the centering of the lever springs on the housing exhausts the predefined tolerance range. For this purpose, the catch arms are positioned on the lever elements. Here, the radial spacing of the catch arms to the lever elements and in particular the twisting of the catch arm relative to the lever element can be set. Here, in one advantageous exemplary embodiment, in each case one positioning surface may be provided on the lever elements in the region of the head part, a positioning surface of the head part being brought into alignment with said positioning surface. It is for example possible for a centering tool to be inserted in each case between two lever elements, which centering tool serves, for both positioning surfaces, as a common stop during the riveting of the catch arms to the lever elements. It is self-evident that the necessary tolerance play is provided for this purpose between the corresponding rivet openings in the lever elements and the rivets. 
     As an alternative to this, the head part of the catch arms may have an axially folded-over projection which bears against the positioning surface of the lever element during the riveting. To attain positioning independently of the radial tolerance of the lever elements, one or more centering windows may be provided in the lever spring, with respect to which centering windows the individual catch arms are positioned by virtue for example of the position thereof in relation to the one or more centering windows being defined during the riveting by means of a centering tool, for example a jig. 
     Alternatively, the catch arms may be held on an annular part which is supported axially on that side of the lever elements which faces away from the housing. The annular part and catch arms may particularly advantageously be formed in one piece, it being possible for this purpose for said annular part and catch arms to be punched from sheet metal and realized by means of deformation processes. Furthermore, a component of said type may be produced from plastic, for example by means of an injection molding process. 
     In one advantageous embodiment, the transport device is moved with the lever tongues during an actuation of the friction clutch. For this purpose, as mentioned above, the catch arms are held individually on lever elements, or the complete annular part is moved with the catch arms. Here, the annular part is supported axially on an actuating bearing of the actuating system, or the annular part is held axially between the actuating bearing and the lever tips. 
     Here, in the first embodiment, the annular part may be arranged radially outside the actuating bearing and have a plurality of circumferentially distributed, radially inwardly aligned tongues which are driven by the actuating bearing. Said tongues may be arranged—as viewed circumferentially—in intermediate spaces left free between the lever tips. Here, the catch arms may be arranged on the inner circumference of the annular part and, in the intermediate spaces between the lever elements, inserted axially into the openings of the housing. 
     In the second embodiment, the annular part may be arranged at a diameter of the actuating bearing and may be subjected to load axially by the latter, wherein the annular part is in abutting contact with the lever tips and applies load to these when subjected to load by the actuating bearing. So as not to restrict the free inner diameter of the lever tips, of the annular part matched thereto and of the housing, the catch arms may be arranged on the outer circumference of the annular part and, as mentioned above, extend axially and an intermediate space of the lever elements. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be explained in more detail on the basis of the exemplary embodiments shown in  FIGS. 1 to 16 , in which: 
         FIG. 1  shows a clutch unit having transport locks in a perspective illustration, 
         FIG. 2  shows a detail of a clutch unit having a transport lock according to the invention, 
         FIGS. 3 to 6  show a schematic illustration of the mode of operation of the transport lock of the clutch unit of  FIG. 2  in different operating states, 
         FIG. 7  shows an alternative exemplary embodiment of a clutch unit to the clutch unit shown in  FIGS. 2 to 6 , 
         FIG. 8  shows an annular part of the transport lock of  FIG. 7 , 
         FIGS. 9 to 11  show a schematic illustration of the mode of operation of the transport lock of the clutch unit of  FIG. 7  in different operating states, 
         FIG. 12  shows an alternative exemplary embodiment of a clutch unit to the clutch units shown in  FIGS. 2 to 11 , 
         FIG. 13  shows an annular part of the transport lock of  FIG. 12 , 
         FIGS. 14 to 16  show a schematic illustration of the mode of operation of the transport lock of the clutch unit of  FIG. 12  in different operating states, 
         FIGS. 17 to 19  show detail illustrations of clutch units with catch arms positioned with respect to the lever elements, 
         FIG. 20  shows a detail of a clutch unit having a lever arm fastened to a side, which is situated opposite the housing, of a lever element, and 
         FIGS. 21 and 22  show a comparison, in section, of catch arms arranged on the lever elements at different sides. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  shows a perspective illustration of a clutch unit  101  in the form of a double clutch having the friction clutches  102 ,  103 , the clutch disks  104 ,  105 , the counterpressure disk  108  arranged between the pressure plates  109 ,  110 , the housing-like or cover-like drive plate  111 , the housing  112  which is axially fixedly connected to the counterpressure plate  108 , the cage-like or housing-like traction means  117  which is fixedly connected to the pressure plate  110 , the plate-spring-like lever elements  115 ,  116 , the adjusting device with the adjusting rings  120 ,  128 , the sensor rings  124 ,  131 , the sensor element  132  which serves as a clamping spring for the sensor ring  131 , the sensor element  125  which serves as a clamping spring for the sensor ring  124 , and the bearing  108   a . Also shown is a tangentially arranged leaf spring pack  150  which is fixedly connected with one circumferential end to the pressure plate  109  and with the other circumferential end to the housing  112 . The leaf spring pack  150  is axially preloaded in such a way that, as already mentioned, the pressure plate  109  is loaded against the lever element  115 , in such a way that the adjusting ring  128  is clamped between the lever elements  115  and the housing  112 . It is preferable for three such leaf spring packs  150  to be provided distributed uniformly over the circumference. 
       FIG. 1  also shows a connecting point  151  in the region of which the drive plate  111 , the counterpressure plate  108  and the housing  112  are fixedly connected to one another. A positioning pin  152  is shown in the region of the connecting point  151 . It can also be seen from  FIG. 1  that the housing-like traction means  117  has axial feet or lugs  117   a  by means of which it is fixedly connected to the pressure plate  110 . It can also be seen from  FIG. 1  that at least the pressure plates  109 ,  110  and the counterpressure disk  108  have, on their circumference, radial projections which are offset circumferentially with respect to one another and serve for producing the required axial connections to the associated components. 
     To ensure that no unintended adjustment at least within the adjusting devices assigned to the two friction clutches  102 ,  103  occurs during the transportation of the clutch unit  101  from the manufacturer to the mounting process on the engine at the automobile manufacturer, transport locks  153 ,  154  are provided which are illustrated in an unlocked position in  FIG. 1 . The unlocked position is to be understood to mean the position assumed by the transport locks  153 ,  154  after the clutch unit  101  has been mounted on the drive output shaft of an internal combustion engine or engine and a first actuation has taken place, preferably after at least the engine and transmission have been connected. Even though it may be expedient for such transport locks to also be unlocked by manual means, it is particularly advantageous for said transport locks to automatically ensure the unlocking action. This may take place for example on account of inherent elasticities. The transport locking means  153 ,  154  are thus mounted, during the mounting of the clutch unit  101 , in a braced position such that the transport locking means  153 ,  154  can be relieved of load by means of actuation of the corresponding friction clutch. The transport locking means may then elastically relax, and thereby release the initially blocked adjusting devices. 
     It can be seen from  FIG. 1  that for example the transport locking means  153  for the friction clutch  103  are formed by spring hoops which are supported by the housing-like component  112  and which have a frame-like region  155 . Said frame-like region  155  can be pivoted radially inward, specifically over the supports  156  provided on the levers of the lever springs  116 . In this way, the supports  156  can be supported axially with preload against the transport locking means  153 , as a result of which, for transportation, the lever springs  116  can be held in a defined axially braced state which ensures that in particular the different rings of the adjusting device remain axially braced and therefore cannot cause any undesired adjustment. 
     During the first actuation of the friction clutch  103 , the lever spring  116  is pivoted such that the tongues  156  relieve the frame-like region  155  of load, as a result of which said frame-like region  155  can spring back radially outward and assume the state illustrated in  FIG. 1 . The transport locks  154  for the friction clutch  102  or the adjusting device assigned thereto operate according to an identical or similar principle. 
       FIG. 2  shows a detail of a clutch unit  1  which is similar to the clutch unit  101  of  FIG. 1  and which has the transport lock  2  according to the invention. To form the transport lock  2 , a plurality of circumferentially distributed catch arms  4  are held on, for example riveted by means of the rivets  5  to, the lever tips  3  of the lever elements  15 . The catch arms  4  extend through the housing  6 , which is similar to the housing  112  of  FIG. 1 , through the openings  7  which are provided radially spaced apart from the inner circumference  8  of the housing  6 . The openings  7  are open to the inner circumference  8  by means of radially extending slots  9 , such that the catch arms  4  can be inserted into the openings  7  proceeding from the inner circumference  8 . For this purpose, the catch arms  4  may be of elastic design and preloaded radially against the inner circumference  8  during mounting. 
     On the free end  10 , which is situated opposite the end facing toward the lever tips  3 , of the catch arms  4  is provided a catch hook  11  which is widened as viewed in the circumferential direction and which forms an axial stop  12  on the opening  7 . The catch arms  4  may be punched from sheet metal and pressed into their final shape. 
       FIGS. 3 to 6  show the clutch unit  1  and the function of the transport lock  2  of  FIG. 2 , in each case on the basis of a schematic half-section, in different states of mounting and during operation.  FIG. 3  shows the clutch unit  1  during the mounting of the lever elements  15 , which are joined together to form a lever spring  13 , onto the housing  6 . During the centering of the lever spring  13  on the housing  6 , the catch arms  4  are radially preloaded with respect to the inner circumference. During the axial movement of the lever spring  13  with respect to the housing  6 , the catch hook  11 , as a result of its extended profile, prevents a snapping-in into the opening  7 . When the catch hook  11 —as shown in FIG.  4 —has passed the slot  9  shown in  FIG. 2 , the catch arms  4  snap into the openings  7  with a release of the preload, as a result of which the catch hooks  11  form an undercut and therefore an axial stop on the rear side of the housing  6 , such that the lever elements  15  are held in a slightly preloaded position and therefore prevent an uncontrolled adjustment of the adjusting device assigned thereto. 
       FIG. 5  shows the clutch unit  1  in the installed position when the friction clutch is disengaged. The lever elements  15  are loaded at least slightly in the actuating direction, such that the catch lugs  11  are lifted from the housing  6 , by the actuating system which loads the actuating bearing  14  which axially moves the lever tips  3 .  FIG. 6  shows the engaged state of the friction clutch of the clutch unit  1  with the lever tips  3  under maximum loading. During the further course of clutch operation, the lever tips  15  are moved between the positions shown in  FIGS. 5 and 6  by the actuating system by means of the actuating bearing  14 . In the event of a dismounting of the clutch unit  1 , the catch hooks  11  return to the axial stop on the housing  6  and prevent a complete relaxation of the lever elements  15 , such that the clutch unit  1  and therefore the friction clutch assigned to the lever elements  15  are dismounted and assessed in their present operating state. Furthermore, the transport lock  2  is available again in the event of a reinstallation of the clutch unit. 
     The transport lock  2  has no parts which project into the installation space of the actuating system, and therefore takes up no additional installation space in relation to the actuating system. Sufficient space is available for the catch arms in the installation space axially in the direction, in which the catch arms  4  extend during an actuation, of the counterpressure plate  108  ( FIG. 1 ). 
       FIG. 7  shows a detail of a clutch unit la slightly modified in relation to the clutch unit  1  shown in  FIGS. 2 to 6 , having a transport lock  2   a  comprising an annular part  16  on which, in the exemplary embodiment shown, the catch arms  4   a  are integrally arranged in a circumferentially distributed manner. The annular part  16  is designed in terms of its diameter such that it comes to bear against the lever tips  3  of the lever elements  15  which are joined together to form a lever spring  13 . The catch arms  4   a , at the outer circumference of the annular part  16 , are guided through intermediate spaces  17  of the lever elements  15  and axially through openings  7   a  of the housing  6 . 
     The formation of the leadthrough of the catch arms  4   a  and the formation of the undercut of the catch arms  4   a  in relation to the housing  6  takes place independently of the use of an annular part  16  in an alternative way to that in  FIGS. 2 to 6 , by virtue of the profile  18  of the catch aims  4   a  being adapted to the cross section of the openings  7   a , which are closed in the direction of the inner circumference  8  of the housing  6 , in such a way that, after a twisting of the free end  10   a  of the catch arms  4   a  about their longitudinal axis, a catch hook  11   a  is formed which can no longer pass the opening  7   a  and therefore an axial stop  12  is formed by the housing  6 , and secondly, the catch hook  11   a  forms an undercut with respect to the housing, which undercut is supported axially on that side of the housing  6  which faces away from the lever spring  13 , and which undercut holds the lever spring  13  or the lever elements  15  under a slight preload, and thereby prevents an uncontrolled adjustment of the adjusting device, in the non-installed state of the clutch unit  1   a.    
       FIG. 8  shows the annular part  16  of  FIG. 7  in detail. The catch arms  4   a  of the annular part are angled and have a rectangular profile  18  which, in the region of the free end  10   a , has a constriction  19 , such that twisting of the catch hook  11   a  is simplified and can take place at a defined position. 
       FIGS. 9 to 11  show the clutch unit  1   a  and the function of the transport lock  2   a  of  FIG. 7  in each case on the basis of a schematic half-section in different states before final assembly in the drivetrain and during operation.  FIG. 9  shows the clutch unit in the finished, not yet installed state. The already twisted catch hooks  4   a  form an undercut on the axial stop  12  of the housing  6 , as a result of which the catch arms  4   a  arranged on the annular part  16  and guided through the intermediate spaces  17  between the lever elements  15  hold the lever elements  15  axially under preload by virtue of the annular part  16  being supported on the lever tips  3 .  FIGS. 10 and 11  show the clutch unit la in the installed state when the clutch is open, that is to say in the disengaged position ( FIG. 10 ) and when the clutch is closed, that is to say in the engaged position ( FIG. 11 ). Here, corresponding to the illustration of  FIGS. 5 and 6 , the lever elements  15  are loaded by the actuating bearing  14 . In contrast to said Figures, the catch arms  4   a  need not be fastened to the lever elements  15 , since the annular part  16 , in the installed state of the clutch unit  1   a , is braced between the actuating bearing  14  and the lever tips  3 . 
       FIG. 12  shows a variant of the clutch unit  1   a  shown in  FIGS. 7 to 11  in the form of the clutch unit  1   b , in which a modified annular part  16   a  is used to form the transport lock  2   b . The annular part  16   a  is designed in terms of its diameter so as to be arranged radially outside the lever tips  3 . As a result, the catch aims  4   a  are provided on the inner circumference of the annular part  16   a . The design of the catch arms  4   b  and the leadthrough through the openings  7   a  of the housing  6  otherwise correspond to the clutch unit  1   a  of  FIGS. 7 to 11 . In contrast thereto, the annular part  16   a  has a plurality of—in this case three—circumferentially distributed tongues  20  which are directed radially inward and which substantially correspond to the inner diameter of the lever elements  15  of the lever spring  13  and which may be designed correspondingly to the lever tips  3 . 
     In the non-installed state of the clutch unit  1   b , the lever elements  15  are held, correspondingly to the explanations of the preceding  FIGS. 2 to 11 , under a slight preload by virtue in this case of the annular part  16   a  being supported axially on that side of the lever elements  15  which faces away from the housing  6 , with the catch arms  4   b  which are integrally connected to the annular part  16   a  being supported, by means of the catch hooks  11   a , on the axial stop  12  of the housing  6  on that side of the latter which faces away from the lever elements  15 . However, the detail of the clutch unit  1   b  illustrated in  FIG. 12  shows not the state of the clutch unit  1   b  not yet installed in the drivetrain, but rather an operating state in the installed position. 
       FIG. 13  shows the annular part  16   a  with the catch arms  4   b  and the radially inwardly directed tongues  20  in detail. 
       FIGS. 14 to 16  show the clutch unit  1   b  and the function of the transport lock  2   b  of  FIG. 12  in each case on the basis of a schematic half-section in different states before final mounting in the drivetrain and during operation.  FIG. 14  shows the clutch unit  1   b  in the non-installed state. As a result of the annular part  16   a  and the catch arms  4   b , the lever elements  15  and housing  6  have a spacing to one to one another which does not permit a complete relaxation of the lever elements  15 . The tongues  20  have no function in this state.  FIGS. 15 and 16  show the clutch unit  1   b  in the installed state in each case in the disengaged and engaged positions. Here, the tongues  20 , which as viewed circumferentially are situated in intermediate spaces between the lever tips, are loaded together with the lever tips  3  by the actuating bearing  14 , such that—as shown in FIG.  15 —the catch hooks  11   a  are lifted from the axial stop  12  of the housing already in the non-actuated state of the friction clutch as a result of more intense preloading of the lever elements  15  by the transport lock  2   b . Correspondingly, when the friction clutch is engaged—as shown in FIG.  16 —the annular part  16   a  and therefore the catch arms  4   b  are driven yet further by the tongues  20 . 
     The exemplary embodiment shown in  FIGS. 12 to 16  has the advantage that the tongues  20  provided in the intermediate spaces of the lever elements  16  have no axial space requirement between the actuating bearing  14  and the lever tips  3 , such that axial installation space is saved. 
       FIG. 17  shows a detail view of a clutch unit similar to the clutch unit  1 , with the lever spring  13  viewed from the inside of the clutch unit. The catch arm  4   c  is attached, for example—as shown—riveted by means of the head part  22  thereof and the rivet  5 , to that side  21  of the lever element  15  which faces toward the housing  6  ( FIG. 2 ). To position the catch arm  4   c  in particular with regard to the angular position of the catch hook  11  with respect to the lever element  13  and therefore with respect to the housing  6  and its openings  7  ( FIG. 2 ), positioning surfaces  23 ,  24  are provided in each case on the lever element  15  and on the head part  22 , which positioning surfaces  23 ,  24  are aligned relative to one another during the riveting process, for example by virtue of a common contact surface being introduced against which both positioning surfaces can be laid. It is self-evident that said process may take place simultaneously for all catch arms  4   c  distributed over the circumference at the same time and if appropriate by means of a single centering tool. 
       FIG. 18  shows a further solution to the embodiment of  FIG. 17  for the positioning of the catch arm  4   d  on the lever element  15 . For this, the head part  22   a  has an axially folded-over projection  25  which is laid against the positioning surface  23  of the lever element. 
       FIG. 19  shows a further, alternative embodiment, modified in relation to the exemplary embodiments of  FIGS. 17 and 18 , of a catch arm  4   e  positioned on the lever element  15 . For this, the head part  22   b  has two positioning surfaces  24   a ,  24   b . For this, at least one, preferably a plurality of centering openings  26  with positioning surfaces are provided on the lever spring  13 , with respect to which positioning surfaces the catch arm, or said catch arm and the further catch arms (not illustrated) distributed over the circumference, are positioned during the riveting process. For this purpose, provision may be made of a common centering tool, for example in the form of a jig, which is aligned with the centering openings  26  and into the openings of which the catch arms  4   e  are inserted. 
       FIG. 20  shows a detail, in a view of the lever spring  13  from the outside, of an arrangement of the catch arms  4   f  on the lever element  15  alternative to the arrangement of  FIGS. 2 to 6  and  17  to  19 . Here, the head part  22   c  is arranged on that side  28  of the lever element  15  which faces away from the housing  6  ( FIG. 2 ), such that the catch arm  4   f  engages axially over the lever element  15  for example by virtue of the lever element  15  being radially partially cut out—as is shown—or by virtue of the catch arm being led through between two adjacent lever elements. Here, the tensile force of the catch hook  11  for axially securing the lever spring  13  is supported over a large area via the head part  22   c  on the lever element  15 , such that the rivet  5  is subjected at most to a reduced tensile loading and the area of the closing head thereof can be reduced and the catch arm  4   f  can thereby—if desired—be relocated radially inward for the same material loading. As a result of the axial support of the catch arm  4   f  by means of the head part  22   c  on the edge  29  of the lever element  15 , the lever conditions, defined by the radial spacing between the catch hook  11  and edge  29 , under tensile loading are positive because smaller lever spacings can be set. In this regard,  FIGS. 21 and 22  show a comparison of the different types of fastening of the catch arms to the sides  21 ,  28  of the lever element  15 . Here, the levers H 1 , H 2  set between the catch hook  11  and the axial support of the head parts  22 ,  22   c  influence the material stress of the catch arms  4   c ,  4   f.    
     In  FIG. 21 , the catch arm  4   c  is riveted by means of the rivet  5  to the lever element  15  on that side  21  which faces toward the housing  6  ( FIG. 2 ). Under tensile loading of the catch hook  11 , the head part  22  is supported axially, so as to set the lever H 1 , on the rivet head of the rivet  5 . In  FIG. 22 , the catch arm  4   f  is riveted by means of the rivet  5  to the lever element  15  on that side  28  which faces away from the housing  6  ( FIG. 2 ). Under tensile loading of the catch hook  11 , the head part  22   c  is supported on the edge  29  of the lever element  15 , as a result of which a lever H 2  smaller than the lever H 1  of  FIG. 21  is set between the head part  22   c  and the catch hook  11 . 
     LIST OF REFERENCE SYMBOLS 
     
         
           1  Clutch Unit 
           1   a  Clutch Unit 
           1   b  Clutch Unit 
           2  Transport Lock 
           2   a  Transport Lock 
           2   b  Transport Lock 
           3  Lever Tips 
           4  Catch Arm 
           4   a  Catch Arm 
           4   b  Catch Arm 
           4   c  Catch Arm 
           4   d  Catch Arm 
           4   e  Catch Arm 
           5  Rivet 
           6  Housing 
           7  Opening 
           7   a  Opening 
           8  Inner Circumference 
           9  Slot 
           10  Free End 
           10   a  Free End 
           11  Catch Hook 
           11   a  Catch Hook 
           12  Axial Stop 
           13  Lever Spring 
           14  Actuating Bearing 
           15  Lever Elements 
           16  Annular Part 
           16   a  Annular Part 
           17  Intermediate Space 
           18  Profile 
           19  Annular Surface 
           20  Tongue 
           21  Side 
           22  Head Part 
           22   a  Head Part 
           22   b  Head Part 
           22   c  Head Part 
           23  Positioning Surface 
           24  Positioning Surface 
           24   a  Positioning Surface 
           24   b  Positioning Surface 
           25  Projection 
           26  Centering Opening 
           27  Positioning Surface 
           28  Side 
           29  Edge 
           101  Clutch Unit 
           102  Friction Clutch 
           103  Friction Clutch 
           104  Clutch Disk 
           105  Clutch Disk 
           108  Counterpressure Plate 
           108   a  Bearing 
           109  Pressure Plate 
           110  Pressure Plate 
           111  Drive Plate 
           112  Housing 
           115  Lever Element 
           116  Lever Element 
           117  Traction Means 
           117   a  Lug 
           120  Adjusting Ring 
           124  Sensor Ring 
           125  Sensor Element 
           128  Adjusting Ring 
           131  Sensor Ring 
           132  Sensor Element 
           150  Leaf Pring Pack 
           151  Connecting Point 
           152  Positioning Pin 
           153  Transport Lock 
           154  Transport Lock 
           155  Frame-Like Region 
           156  Support Tongue 
         H 1  Lever 
         H 2  Lever