Abstract:
A padlock for securing a switch of an industrial plant comprises a lock body and a hoop which is displaceably held at the lock body, wherein the lock body has a lock housing composed of plastic, a lock cylinder having a rotatable cylinder core, and a rotatable latching member, wherein the cylinder core and the latching member are rotationally fixedly coupled to one another by means of a coupling element and wherein the latching member is rotatable from a release position into a latching position to lock the hoop at the lock body. The padlock is characterized in that the coupling element has at least one first bearing section, one second bearing section and therebetween a shaft section between the latching member and the lock cylinder, said shaft section connecting the first bearing section to the second bearing section and having a smaller diameter than the two bearing sections.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority of German Patent Application DE 102013207268.6 filed on Apr. 22, 2013. 
       FIELD OF THE INVENTION 
       [0002]    The invention relates to a padlock for securing a switch of an industrial plant. The padlock comprises for this purpose a lock body and a hoop which is displaceably held at the lock body, wherein the lock body has a lock housing composed of plastic, a lock cylinder having a rotatable cylinder core, and a rotatable latching member, wherein the cylinder core and the latching member are rotationally fixedly coupled to one another by means of a coupling element and wherein the latching member is rotatable from a release position into a latching position to lock the hoop at the lock body. 
       BACKGROUND OF THE INVENTION 
       [0003]    A particular area of application of a padlock is in the field of occupational safety. There is the risk in relation with the servicing of industrial plants, for example of a production machine, that the industrial plant deactivated for the purpose of servicing work is activated again by accident while the servicing work is still continuing. A substantial danger for the service engineer can result from this. It is therefore customary that the service engineer moves a switch associated with the industrial plant to an OFF position for the duration of the servicing work and secures it in this position, i.e. the switch is directly blocked or access to the switch is blocked. The named switch is typically an energy supply switch, for example a main electrical switch of a control device or of an energy supply device of the industrial plant (e.g. power switchbox). Alternatively to this, the named switch can, for example, be a valve of a liquid line or of a gas line. 
         [0004]    In order effectively to avoid an accidental activation of the industrial plant by another person, each service engineer hangs a padlock on the named switch or on a blocking device associated with the switch before starting his work and locks said padlock. The switch is hereby secured in its OFF position, i.e. the switch cannot be moved accidentally back into an ON position by another person. When the service engineer has ended his work, he unlocks the padlock again and releases it from the switch. Each service engineer usually has his own individual padlock (or a plurality of his own individual padlocks) associated with him. This procedure is also called a lockout. The padlock used is accordingly called a lockout lock. 
         [0005]    So that a plurality of service engineers can block and release the switch again independently of one another, a plurality of receivers (e.g. eyelets) can be provided at the switch for hanging a plurality of lockout locks. If only a single receiver for a lockout lock is provided, a securing claw can be used which is hung into the respective eyelet of the switch or of the associated blocking device and which in turn has a plurality of hang-in eyelets for a respective padlock. Only when the last padlock has been removed from the securing claw can the securing claw be removed from the switch so that it can again be brought into the ON position. 
         [0006]    It is known in connection with such a securing of a switch of an industrial plant to equip the lockout lock used with a housing of plastic, with a hoop being displaceably held at the lock housing and with a lock cylinder being arranged in the lock housing. The lock cylinder can selectively be brought from an open position into a latching position to latch the hoop to the lock housing after the hoop has, for example, been hung into an eyelet of the switch. By forming the lock housing from plastic, a particularly light padlock results which is of advantage in the use as a lockout lock since the service engineers occasionally carry a plurality of lockout locks simultaneously. A housing of plastic can also contribute to a desired electrical insulation. By the use of a plastic housing, there is furthermore a particularly simple possibility of color marking the padlock. The smaller stability of a plastic housing in comparison with a lock housing made of metal does not represent any serious disadvantage in a lockout lock since the padlock only serves the purpose of securing a switch against unintentional actuation, but not, for example, as theft protection. 
         [0007]    It is furthermore known by prior use by the Safety Padlock No. 411 of the Masterlock company to design the lock housing as elongate, i.e. to configure a length of the lock housing as substantially larger than a maximum width of the lock housing. It is thereby possible to apply wording in two languages, for example, to such an enlarged surface of the lock housing which warns against the removal of the lockout lock. For instance, a warning in English can be printed in the upper region of the lock housing and a corresponding warning in Spanish can be printed in the lower region of the lock housing, for example. Alternatively, a photo of the respective service engineer person can be applied to the lock housing so that it is immediately recognizable who has attached the lock. To be able to extend the lock housing of the padlock in this manner, a coupling element can be provided in the lock housing which connects the latching member and the cylinder core to one another in a rotationally fixed manner. The coupling element in this respect has to be configured the longer, the longer the length of the lock housing is. 
         [0008]    In the Safety Padlock No. 411 known by prior use, the coupling element and the latching member are configured in one part as a zinc die-cast part, with the coupling element being made as a full cylinder. The coupling element is supported on reinforcement ribs of the lock housing, which is known, for example, from U.S. Pat. No. 5,755,121. The lock housing is formed from plastic and is in this respect composed of two halves. 
         [0009]    Both a manufacture by an injection molding process and a welding of the halves of a lock housing suffer from large tolerances, which can have the result that the reinforcement ribs jam the coupling element or the coupling element is seated too loosely between the reinforcement ribs. Consequently, a high frictional force can be generated, whereby the padlocks are relatively stiff in operation. In addition, particularly with large lengths of the coupling element, a canting of the coupling element at the cylinder jacket surface can occur. In addition, a solid coupling element produced from metal greatly increases the weight of the padlock in a disadvantageous manner. 
         [0010]    Alternatively, the cylindrical coupling element can be guided, for example, in a cylinder jacket surface, whereby a support of the coupling element along the total cylinder jacket surface results. Due to the large surfaces rubbing against one another, a high frictional force is generated which can likewise result in padlocks which are stiff in operation. 
       SUMMARY OF THE INVENTION 
       [0011]    It is an object of the invention to provide a padlock having a coupling element which is characterized by a low weight and a smooth operation. 
         [0012]    This object is satisfied by a padlock having the features of claim  1  and in particular in that the coupling element between the latching member and the lock cylinder has at least one first bearing section, one second bearing section and therebetween a shaft section which connects the first bearing section to the second bearing section and a has a smaller diameter than the two bearing sections. 
         [0013]    The bearing sections of the coupling element are thus made thicker in comparison with the shaft section, whereby a barbell shape of the coupling element can substantially result. Much less material for the coupling element is required in comparison with a fully cylindrical configuration of the coupling element, which results in a lower weight of the coupling element and thus of the padlock. 
         [0014]    In addition, the shaft section of the coupling element advantageously does not contact a support surface of the lock housing which is, for example, cylindrical, for the coupling element. A spacing is therefore provided between the shaft section of the coupling element and an associated inner surface of the lock housing. Only the first and second bearing sections are in contact with the support surface. Due to the much smaller surface of the bearing sections in comparison with a full cylinder, the frictional force between the support surface and the coupling element is greatly reduced. An opening and closing of the padlock is consequently associated with a smaller force effort. 
         [0015]    Advantageous embodiments of the invention are described in the description, in the dependent claims and in the drawings. 
         [0016]    In accordance with a first advantageous embodiment, the first bearing section is arranged at a first end of the coupling element and the second bearing section is arranged at a second end of the coupling element. The coupling element can thus only contact support surfaces of the lock housing in end regions, whereby the coupling element is supported in a particularly stable angular position with respect to an axis of rotation. In addition, a good force-transmitting connection to the latching member and to the lock cylinder can result due to the end regions of the coupling element enlarged in diameter. 
         [0017]    Alternatively, the bearing sections can also be spaced apart from the ends of the coupling element and/or more than two bearing sections having a respective shaft section therebetween can be provided. Only two bearing sections and one shaft section between them are preferably provided between the latching member and the lock cylinder. 
         [0018]    In accordance with a further advantageous embodiment, the bearing sections of the coupling element have cylindrical support surfaces at their periphery. The coupling element can therefore be substantially rotationally symmetrical about an axis of rotation, with the axis of rotation coinciding with the axis of the cylindrical support surfaces and of the shaft section. In this embodiment, the coupling element can be axially displaceably supported in the lock housing, whereby the assembly of the padlock can be simplified in manufacture. 
         [0019]    Alternatively to this, the bearing sections can, for example, have the form of a torus segment, i.e. the support surfaces have the shape of a circular section rotated about the axis of rotation of the coupling element. Other types of curves than a circular form are also possible so that the support surfaces can e.g. correspond to the jacket surface of a barrel shape. 
         [0020]    The lock housing advantageously has a first counter-bearing section and a second counter-bearing section, with the first counter-bearing section forming a plain bearing seat for the first bearing section of the coupling element and the second counter-bearing section forming a plain bearing seat for the second bearing section of the coupling element. The first and second counter-bearing sections of the lock housing can in particular be configured complementary to the first or second bearing section of the coupling element respectively. A counter-bearing can thus be dispensed with in the region of the shaft section, whereby the manufacture of the lock housing can be simplified. 
         [0021]    In accordance with a preferred embodiment, the coupling element is formed from plastic. An embodiment composed of plastic in this respect reduces the weight of the coupling element even further, with the coupling element simultaneously being able to be manufactured simply and inexpensively, for example by an injection molding process. In addition, an electrical insulation between the latching member and the cylinder core is simultaneously provided by a coupling element formed from plastic. In combination with the lock body formed from plastic, a complete electrical insulation can be provided between the hoop and the latching member, on the one hand, and the cylinder core into which a key can be inserted, on the other hand. 
         [0022]    To fix the hoop in the lock housing, the latching member preferably displaces and/or blocks at least one latch element in a latching position, said latch element coming into engagement with the hoop. For example, the latch element can be formed by two blocking balls which engage into spherical cut-outs of the hoop and thus prevent a pulling of the hoop out of the lock housing in the locked state. 
         [0023]    In accordance with a further advantageous embodiment, a transition section in which the diameter of the coupling element continuously reduces is provided between the shaft section and the respective bearing section of the coupling element. The coupling element thus tapers in the transition region so far until the diameter of the shaft section is achieved. The transition section can, for example, have a contour of part circle shape or of part elliptical shape, with other curves, however, also be being possible. Due to such a continuous diameter reduction, a higher stability of the coupling element toward torsion forces results so that an even smaller diameter of the shaft section can be realized with respect to a coupling element with a purely step-shaped transition between the respective bearing section and the shaft section with the same stability. 
         [0024]    In accordance with a further advantageous embodiment, the cylinder core has an output section and the coupling element has a first coupling section at the first end, with the output section and the first coupling section being in form-fitted engagement with one another. The first coupling section and the output section in this respect serve to couple the cylinder core reliably and rotationally fixedly to the coupling element. To provide a rotationally fixed coupling, the first coupling section can, for example, be of part circle shape, in particular of semicircular shape, a straight web or a slot. In a complementary manner hereto, the output section can likewise be of part circle shape, in particular of semicircular shape or a slot or a web. 
         [0025]    A simple, force-transmitting connection between the coupling element and the lock cylinder advantageously results by the structure of part-circle shape. In addition, the surface which contacts the first counter-bearing section is further reduced by the semicircular cut-out of the coupling section. Different materials for the coupling element and the locking element can also hereby be used. 
         [0026]    In accordance with a further advantageous embodiment, the coupling element and the latching member are formed by separate parts. The coupling element and the latching member can thus be manufactured separately from one another. Coupling elements of different lengths can thereby be provided, for example, with the length of the coupling element being adapted to the length of the lock housing. 
         [0027]    In accordance with a further advantageous embodiment, the coupling element has a second coupling section at the second end and the latching member has a drive section, with the second coupling section and the drive section being in force-transmitting engagement with one another. The second coupling section and the drive section can in this respect be formed in the same different manners as the output section and the first coupling section. 
         [0028]    The second coupling section and the drive section are advantageously formed identically with the output section and the first coupling section, whereby a symmetrically shaped coupling element can result. Consequently, a correct orientation of the coupling element does not have to be considered in the assembly of the padlock. 
         [0029]    In accordance with an alternative embodiment, the coupling element is an integral part of the latching member. The coupling element and the latching member can therefore be formed by a single component, whereby the assembly of the padlock can be simplified. 
         [0030]    In accordance with a further advantageous embodiment, the lock body, as already mentioned, has at least one latch element (e.g. two blocking balls) which is movably supported in a locking region of the lock housing, with the latching member being adapted to urge the latch element in the latching position radially in the direction of the hoop with respect to an axis of rotation of the latching member to lock the hoop to the lock body. In this respect, the first bearing section and the second bearing section of the coupling element can be arranged in an extension region of the lock housing which is arranged axially between the locking region of the lock housing and the lock cylinder with respect to the axis of rotation of the latching member. 
         [0031]    The coupling element is advantageously oriented along an axis of rotation of the cylinder core, with the coupling element being longer, viewed in the direction of the axis of rotation of the cylinder core, than the respective diameter of the bearing sections. The axis of rotation in this respect extends in a direction between the lock cylinder and the latching member. To achieve a length of the lock housing which is as large as possible, the coupling element can thus be configured as longer than the respective diameter of the bearing sections. The length of the coupling element can in particular be twice the size as a maximum diameter of the bearing sections. The possibility is provided by a variation of the length of the coupling element to vary and in particular to extend the dimensions of the padlock in a wide range without, for example, the latching member and the lock cylinder having to be modified. An increase in size of the lock housing is furthermore possible without the weight of the padlock increasing greatly. 
         [0032]    In accordance with a further advantageous embodiment, the lock housing is at least twice as long in the direction of an axis of rotation of the coupling element than the maximum width of the lock housing in a direction perpendicular to the axis of rotation of the coupling element. The lock housing is thus at least twice as “high” as “wide”, whereby sufficient space can be provided for a bilingual wording on the lock housing or for the attachment of a photo of the respective service engineer. A warning against the removal of the padlock can, for example, be applied in two languages to the lock housing, whereby the padlock can preferably be used in facilities that employ staff with different mother tongues. 
         [0033]    The invention furthermore comprises a padlock for securing a switch of an industrial plant, having a lock body and a hoop which is displaceably held at the lock body, wherein the lock body has a lock housing composed of plastic, a lock cylinder having a rotatable cylinder core and a rotatable latching member, wherein the cylinder core and the latching member are rotationally fixedly coupled to one another by means of a coupling element and wherein the latching member is rotatable from a release position into a latching position to lock the hoop at the lock body. The alternative padlock in accordance with the invention is characterized in that the coupling element and the latching member are formed by separate parts, wherein the coupling element is supported at at least one first counter-bearing section and one second counter-bearing section of the lock housing and the lock housing comprises a throughgoing release section between the first and the second counter-bearing sections, in which release section the lock housing is set back from the counter-bearing sections and is hereby spaced apart from the coupling element. 
         [0034]    The advantage is also achieved by this alternative padlock that the coupling element only contacts the counter-bearing sections of the lock housing with a small surface. Consequently, on a rotation of the coupling element, only small frictional forces are generated, whereby the padlock in accordance with the invention can be operated smoothly. The advantage of the small frictional forces is in particular also present when the coupling element is formed as a full cylinder since the contact surface of the full cylinder is greatly reduced by the release section of the lock housing. 
         [0035]    The coupling element and the latching member can be manufactured from different materials due to the configuration of the coupling element and the latching member as separate parts. This makes it possible, for example, to manufacture the latching member from metal to achieve a stability which is as high as possible. The coupling element can be formed from plastic to save weight. 
         [0036]    In accordance with an advantageous embodiment, the coupling element has a first end and a second end, wherein the coupling element is supported by the first end at the first counter-bearing section of the lock housing and by the second end at the second counter-bearing section of the lock housing. 
         [0037]    In accordance with a further advantageous embodiment, the coupling element is only supported at the first counter-bearing section and the second counter-bearing section of the lock housing. The coupling element can thus be supported at the lock housing solely by the two counter-bearing sections, whereby friction can only occur at the counter-bearing sections. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0038]    The invention will be explained in the following only by way of example with reference to the drawings. Elements which are the same or of the same kind are marked by the same reference numerals therein. 
           [0039]    There are shown: 
           [0040]      FIG. 1  a padlock in accordance with the invention in an exploded view; 
           [0041]      FIG. 2  a sectional view of the padlock of  FIG. 1  in assembled form; 
           [0042]      FIG. 3  a sectional view of a second embodiment of a padlock in accordance with the invention in assembled form; 
           [0043]      FIG. 4   a  a perspective representation of a first embodiment of a coupling element; 
           [0044]      FIG. 4   b  a perspective representation of a second embodiment of a coupling element; 
           [0045]      FIG. 4   c  a perspective representation of a third embodiment of a coupling element; 
           [0046]      FIG. 4   d  a perspective representation of a fourth embodiment of a coupling element; and 
           [0047]      FIG. 5  a sectional view of a third embodiment of a padlock in accordance with the invention in assembled form. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0048]    The padlock  10  shown in  FIG. 1  comprises a lock housing  12  and a hoop  14 . The lock housing  12  is manufactured in one piece peripherally, whereby a welding of housing parts suffering from tolerances can be avoided. The hoop  14  has a U shape with one shorter limb and one longer limb. An inwardly directed locking recess  16  is formed at both limbs of the hoop  14 . Furthermore, a ring groove  18  with an abutment head  20  adjacent to it is provided at the free end of the longer limb. 
         [0049]    The lock housing  12  is configured for receiving a further housing part which is configured as an inner housing  22  in the embodiment shown. The lock housing  12  and the inner housing  22  are formed from a plastic. The inner housing  22  can be inserted into the lock housing  12  and can be fixed to the lock housing  12  by means of a securing screw  24 , as will be explained in the following. The lock housing  12  and the inner housing  22  accommodate a lock cylinder  26  and a locking mechanism  28  which are arranged spaced apart from one another. The locking mechanism  28  is arranged in a locking region  29  which is formed by the upper region of the lock housing  12  ( FIG. 2 ). The spacing between the lock cylinder  26  and the locking mechanism  28  is bridged by a coupling element  30 . The coupling element  30  has at a first end a first bearing section  32  which is substantially cylindrical and comprises a semicircular first coupling section  34   a  (cf.  FIG. 4   a ). The first coupling section  34   a  is in this respect rotationally fixedly coupled to a likewise semicircular output section  36  of a rotatable cylinder core  37  of the lock cylinder  26 . The coupling element  30  is consequently also rotated by a rotation of the cylinder core  37 . 
         [0050]    At its second end, the coupling element  30  comprises a second bearing section  38  which has a semicircular second coupling section  34   b.  The second coupling section  34   b  of the coupling element  30  is rotationally fixedly coupled to a semicircular drive section  40  of a rotational bolt  42  of the locking mechanism  28 . The locking mechanism  28  can thus be actuated by a rotation of the coupling element  30  which is caused by a rotational actuation of the cylinder core  37 . 
         [0051]    The named rotational bolt  42  serves as a latching member and cooperates with two blocking balls  44 . The rotational bolt  42  has a substantially cylindrical shape, wherein two receiving recesses  46  are arranged at the jacket surface of the rotational bolt  42  and can receive the blocking balls  44  in part on an opening actuation of the lock cylinder  26  and on the rotation of the coupling element  30  and of the rotational bolt  42  associated therewith. At the periphery, in each case adjacent to the receiving recesses  46 , the rotational bolt  42  comprises two locking sections  48  by which the blocking balls  44  can be held in a blocking engagement with the locking recesses  16  of the hoop  14 . 
         [0052]    By a corresponding actuation of the lock cylinder  26 , the padlock  10  thus selectively allows the carrying out of the locking of the hoop  14  in the lock housing  12  or the release of the shorter limb of the hoop  14 . The padlock  10  shown is in particular suitable for use as a lockout lock. 
         [0053]      FIG. 2  shows a cross-sectional view of the padlock  10  of  FIG. 1  in the assembled state and with a locked hoop  14 . The inner housing  22  is pushed into the lock housing  12  and is fixed to the lock housing  12  by means of the securing screw  24  and by means of a nut  50  for the assembly of the padlock. The lock cylinder  26 , the locking mechanism  28  and the coupling element  30  are thereby captured in the lock housing  12 . The securing screw  24  is inserted into a hoop receiving passage  52  of the lock housing  12  which is closed by the hoop  14  when the hoop  14  is locked in the lock body  12 —as shown in  FIG. 2 . In the locked state, the securing screw  24  can thus not be reached, whereby in particular the inner housing  22  and thus the lock cylinder  26  cannot be removed from the lock housing  12 . 
         [0054]      FIG. 2  shows a state of the padlock  10  in which the hoop  14  is locked and is thus secured against removal from the lock housing  12 . The locking sections  48  of the rotational bolt  42  hold the blocking balls  44  in a blocking engagement with the locking recesses  16  of the hoop  14  for this purpose. To unlock the padlock  10 , an opening rotational actuation of the lock cylinder  26  by means of an associated key is required. The cylinder core  37 , the coupling element  30  rotationally coupled to the cylinder core  37  and the rotational bolt  42  are hereby rotated about 90° so that a respective receiving recess  46  of the rotational bolt  42  is rotated into the region of the blocking balls  44 . The blocking balls  44  can thus move back out of the locking recesses  16  of the hoop  14 . The hoop  14  can now be pulled out of the lock body  12  axially until the abutment head  20  of the longer hoop limb abuts the respective blocking ball  44 . The shorter limb of the hoop  14  now already projects out of the lock housing  12 . The hoop  14  can now be rotated about the longitudinal axis of the longer hoop limb. Another locking of the hoop  14  in the lock housing  12  takes place in the reverse order. 
         [0055]    On a rotational actuation of the lock cylinder  26  by 90°, the rotational actuation is communicated from the lock cylinder  26  to the rotational bolt  42  by the coupling element  30 . On the rotational movement, the first bearing section  32  and the second bearing section  38  slide along an inner cylinder surface  54  of the inner housing  22  which has a first counter-bearing section  55   a  and a second counter-bearing section  55   b.  The counter-bearing sections  55   a,    55   b  form cylindrical counter-support surfaces which define a plain bearing seat for the coupling element  30  and provide that the coupling element  30  can only carry out a rotational movement, but otherwise remains fixedly positioned and is in particular arranged rotationally fixedly with the cylinder core  37  and the rotational bolt  42 . The counter-bearing sections  55   a ,  55   b  are configured in one piece peripherally. On the rotational actuation of the coupling element  30 , frictional forces thus only arise at the first and second bearing sections  32 ,  38  of the coupling element  30  due to the sliding of the bearing sections  32 ,  38  in the counter-bearing sections  55   a ,  55   b.  A frictional force can additionally be reduced by the selection of a suitable plastic material for manufacturing the coupling element  30 . 
         [0056]    The coupling element  30  communicates a rotation of the cylinder core  37  to the rotational bolt  43  over a length of an axial extension region  57 . The longer the extension region  57  is, the longer the lock housing  12  also is. 
         [0057]    The second embodiment of a padlock  10  shown in  FIG. 3  is substantially identical with the padlock  10  of  FIGS. 1 and 2 , but the rotational bolt  42  and the coupling element  30  are configured as a single component, that is in one piece. The second coupling section  34   b  and the drive section  40  are thus omitted in the embodiment shown in  FIG. 3 . 
         [0058]      FIG. 4   a  shows a perspective view of a possible embodiment of a coupling element  30  which has a first bearing section  32  as well as a second bearing section  38 . The first and second bearing sections  32 ,  38  are connected to one another by a shaft section  56 . The shaft section  56  as well as the first and second bearing sections  32 ,  38  are arranged substantially rotationally symmetrically along an axis  58 . The shaft section  56  has a circular cross-section and additionally has a smaller diameter than the bearing sections  32 , 38  so that the shaft section  56  is directly adjacent to the facing end face of the respective bearing section  32 ,  38  and is set back radially with respect to the respective bearing section  32 ,  38 . 
         [0059]    To establish a rotationally fixed coupling with the cylinder core  37  of the lock cylinder  26  and with the rotational bolt  42 , the first and second bearing sections  32 ,  38  each have a semicircular coupling section  34   a,    34   b  by which it is made possible for the coupling element  30  to transmit a rotational movement of the cylinder core  37  to the rotational bolt  42 . 
         [0060]    A second embodiment of a coupling element  30  is shown in  FIG. 4   b . The coupling element  30  of  FIG. 4   b  is substantially identical with the coupling element  30  of  FIG. 4   a , but differs in that the shaft section  56  has a smaller diameter at its center. Unlike the purely step-shaped transition in accordance with  FIG. 4   a , the shaft section  56  merges in each case with a continuous transition section  60  into the bearing sections  32 ,  38 . The transition section  60 , for example, has a contour of part circle shape or of quarter-elliptical shape, whereby the diameter of the coupling element  30  becomes continuously larger on the transition into the bearing sections  32 ,  38 . At the ends, however, the respective transition section  60  is radially set back in a similar manner as in  FIG. 4   a  with respect to the associated bearing section  32 ,  38 , i.e. the respective transition section  60  is adjacent to the facing end face of the respective bearing section  32 ,  38  and does not extend approximately radially up to the peripheral surface of the respective bearing section  32 ,  38 . 
         [0061]      FIG. 4   c  shows a third embodiment of a coupling element  30 . Unlike the coupling element  30  of  FIG. 4   b , the coupling element  30  of  FIG. 4   c  comprises a shaft section  56  whose cross-section is “+” shaped, i.e. is configured as a crossed bar. The shaft section  56  comprises four limbs  56   a ,  56   b ,  56   c ,  56   d  (also called wings) which extend away from a central point and which each include an angle of 90° with respect to the adjacent limbs  56   a ,  56   b ,  56   c ,  56   d.  The limbs  55   a ,  56   b ,  56   c ,  56   d  extend between the bearing sections  32 ,  38 . The cross-section of the shaft section  56  along a plane A-A in accordance with  FIG. 4   c  is shown in the sectional view of  FIG. 4   d , with the cross-section of the shaft section  56  not varying between the bearing sections  32 ,  38  in the embodiment of  FIG. 4   c.    
         [0062]    Differing from the representation in accordance with  FIG. 4   c , the shaft section  56  can also have a different number of limbs  56   a ,  56   b ,  56   c ,  56   d,  for example three, five, six or eight limbs, so that in the event of a regular angular pitch two adjacent limbs include an angle of 120°, 72°, 60° or 45°. The cross-section of the shaft section  56  in these embodiments can thus generally be called star-shaped with a corresponding number of limbs, i.e. as a star with three or more points. Furthermore, the two side surfaces of a respective limb  56   a ,  56   b ,  56   c ,  56   d  do not necessarily have to extend in a planoparallel fashion, differing from the representation in accordance with  FIG. 4   c , but can rather include an acute angle with respect to one another. 
         [0063]    A fourth embodiment of a coupling element  30  is shown in  FIG. 4   d . As in the embodiment of  FIG. 4   c , the coupling element  30  comprises a shaft section  56  which is formed as a cross-bar and which now, however, comprises two transition sections  60  in accordance with the embodiment of  FIG. 4   b  which, for example, have a contour of part circular shape or of quarter-elliptical shape. The minimal diameter of the coupling element  30  can hereby be configured even smaller, with the diameter of the shaft section  56  becoming continuously larger on the transition into the bearing sections  32 ,  38  due to the transition sections  60 . As in  FIG. 4   c , the shaft section  56  can also have a different number of limbs  56   a ,  56   b ,  56   c ,  56   d.    
         [0064]    A third embodiment of a padlock  10  is shown in  FIG. 5 . This embodiment is substantially identical with the first embodiment of  FIGS. 1 and 2 . However, the coupling element  30  is not configured in the form of a barbell, but as a cylinder. To avoid a large-area friction of the cylindrical coupling element  30  at inner walls of the lock housing  12 , a release section  62  is arranged between the counter-bearing sections  55   a ,  55   b , extends in the peripheral direction of the coupling element  30  and extends in a throughgoing manner from the first counter-bearing section  55   a  up to the second counter-bearing section  55   b.  The release section  62  is radially set back with respect to the counter-bearing sections  55   a ,  55   b.  The release section  62  is configured such that the coupling element  30  is not in contact with the lock housing  12  in the region of the release section  62 .