Abstract:
A releasable coupling, including a first and a second coupling part for transmitting torque, where the first coupling part has a projection which extends in the direction of the geometrical axis of rotation and in the circumferential surface of which a first peripheral groove is embedded, that the second coupling part has a recess which is matched in cross section to a receptacle on the projection and in the circumferential surface of which a second peripheral groove is embedded, that an annular securing element is provided, the securing element being elastically deformable with respect to the contour of its open or closed periphery and, in the separated state of the two coupling parts, being insertable into one or optionally into one of the peripheral grooves and the contour of which, in the separated state of the two coupling parts, projecting out of the peripheral groove.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application is a continuation of pending International patent application PCT/EP2007/064341 filed on Dec. 20, 2007 which designates the United States and claims priority from German patent application 10 2006 062 240.5 filed on Dec. 22, 2006. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to a releasable coupling, preferably for releasable coupling connection of drive and output elements such as shaft ends, comprising a first and a second coupling part with means for transmitting torque. 
       BACKGROUND OF THE INVENTION 
       [0003]    A large number of couplings of this kind of different designs are known. However, if said couplings are couplings which can be connected with a view to being released, complex additional devices are sometimes required for the engagement and disengagement procedures. Secondly, that is to say if the couplings are permanently closed couplings, establishing and releasing the coupling connection is often only possible by way of an assembly/disassembly procedure. Known in particular are couplings of which the two coupling parts have to be screwed to one another in order to transmit torque. This is only possible when, depending on the installation position of the coupling, there is sufficient installation space and an adequate degree of accessibility, but this is not always the case in the desired manner and/or leads to structural constraints. Furthermore, such assembly (disassembly) often also takes an undesirable amount of time. 
         [0004]    Against this background, it is an object of the invention to develop the coupling cited in the introductory part in a manner which is advantageous for use, so that in particular the abovementioned disadvantages may be avoided as far as possible. 
       SUMMARY OF THE INVENTION 
       [0005]    According to the invention, the object is solved first and foremost in conjunction with the features that the first coupling part has a projection which extends in the direction of the geometric axis of rotation (that is to say the rotation axis or longitudinal axis of the coupling) and in the lateral surface of which a first peripheral groove, in particular an annular groove, is formed, that the second coupling part has a recess, the cross-section of which is adapted as a receptacle for the projection and in the lateral surface of which a second peripheral groove, in particular an annular groove, is formed, that a ring-like locking member is provided, which is elastically deformable in terms of the contour of its open or closed periphery, it being possible to insert said locking member into a peripheral groove or selectively into one of the two peripheral grooves when the coupling parts are in the disconnected state, and the contour of said locking member protruding out of this peripheral groove when the two coupling parts are in the disconnected state. It is especially preferred that, in the state in which the two coupling parts are disconnected, the locking member takes up, in the peripheral groove into which it has been inserted, a shape and/or position such that it automatically or necessarily protrudes in a resiliently flexible manner out of said groove. The coupling parts of a coupling of this type can be connected by the projection being inserted into the recess in the longitudinal direction of the coupling, as a result of which the locking member is deformed in a temporary and resilient manner by means of the other coupling part by virtue of the shaping of this other coupling part, that is to say the locking member is either resiliently expanded or compressed depending on the peripheral groove selected for the insertion of the locking member, after which the locking member, while providing axially aligned orientation of the two peripheral grooves, also automatically engages in the further peripheral groove under the prestress of the locking member. The connection state is accordingly achieved by a simple relative movement of the two coupling parts along their geometric axis of rotation or longitudinal axis, it being possible for a small axial movement space to be sufficient for this purpose. By virtue of the prestressed connecting element snapping into the second peripheral groove, the connection state is automatically locked, so that no tool is required for this purpose. It is possible to release the coupling parts by exerting a force on one or both coupling parts counter to the connecting direction, said force being sufficient to produce a force action on the peripheral groove or grooves for renewed resilient deformation of the locking member with radial movement into only one of the two peripheral grooves. It is therefore possible to release the coupling parts with only minimal space for movement and without tools. In this case, the invention provides the possibility of various configurations in order, in particular by virtue of the shaping and dimensioning of the projection and/or recess and of the two peripheral grooves in accordance with the locking member, to determine how high the two force effects required for connecting and for releasing purposes should be (these can be preferably of different magnitudes) or whether accommodation of the locking member in the peripheral groove of the first or second coupling part is advantageous in the released state. 
         [0006]    In terms of shaping and size, the locking member is preferably realised such that it can be inserted into the second or radially outer peripheral groove, and that the inner contour of said locking member protrudes radially inward out of the second peripheral groove into the cross-section of the first recess when the two coupling parts are in the released state, and engages in the first or radially inner peripheral groove when the two coupling parts are in the connected state. As an alternative, it would be possible for the locking member to be insertable into the first peripheral groove and for the outer contour of said locking member to protrude outward from the first peripheral groove when the two coupling parts are in the released state, and to engage in the second peripheral groove also, when the two coupling parts are in the connected state. It is further preferred for the cross-sections of the projection and of the recess to be matched to a common clearance or transition fit and to be bounded in a circular manner, preferably transverse to the geometric axis of rotation or to the longitudinal axis of the coupling. As a result, the projection and the recess can exert a centering effect on the two coupling parts, depending on the configuration. An advantageous configuration can be seen when the locking member used is a round-wire circlip, preferably comprising spring steel, which is open on the periphery. On account of its peripheral opening and the elastic material properties, said round-wire circlip has the desired resiliently flexible peripheral contour, that is to say its diameter or cross-section can be temporarily increased or reduced in size in accordance with the force effect against its resilient restoring force. Furthermore, the round wire-cross-section of such circlips provides advantages for the plug-type coupling according to the invention since it is possible to determine in conjunction with various groove cross-sections of the peripheral, or in particular annular, grooves, the axial force that is to be exerted on the coupling part or the two coupling parts until the desired elastic deformation of the locking member is reached on account of the transmission of force by the first and/or second peripheral, or in particular annular, groove. As an alternative, use may be made of other types of circlips and locking rings and also securing elements of different configuration, in particular also corresponding to the cross-sections of projections and recesses that have a peripheral contour which deviates from the circular line, for example an oval or polygonal or even a non-round or square peripheral contour. In addition, a locking member may be used which has an oval, polygonal or angular cross-sectional shape instead of a round-wire or a circular cross-sectional shape. The material used may be, for example, a plastic, in particular glass- or carbon-fiber-reinforced plastic, or, for example, a bimetal realisation. 
         [0007]    A practical configuration can be seen in the first peripheral groove having, transverse to the peripheral direction, that is to say in cross-section, a rounded cross-section, preferably a cross-section which is in the form of a portion of a circle, more preferably a cross-section which is in the form of a semicircle. In this context, it is further preferred for the second peripheral groove to have, transverse to the peripheral direction, an angular cross-section, preferably a rectangular cross-section, more preferably a square cross-section. A cross-section which is in particular rectangular or square, the corners of which are rounded or chamfered, is also possible. The size of the corner radius of the rounded portion can be selected as desired so that the cross-sectional shape approximates to a semicircle or corresponds to a semicircle. When the connected coupling parts are being released, depending on the cross-section and also depending on the depth to which the locking member engages into the two axially aligned peripheral grooves, conversion of the axial disconnection force into a radial force of comparatively greater magnitude is facilitated, by the, preferably radially inner, peripheral groove of rounded cross-section compared to the second peripheral groove, so that the locking member is radially expanded (that is to say is not radially constricted) and moves to the second, preferably radially outer peripheral groove. This may be still further assisted by virtue of the fact that the locking member has, transverse to the peripheral direction, the round cross-section which has already been discussed, of which round cross-section the cross-sectional radius preferably corresponds to or is slightly less than the radius of the rounded portion of the first peripheral groove and/or of which round cross-section the diameter may be approximately equal to or somewhat less than the width of the second peripheral groove. Provision is preferably made for the locking member to be inserted into the second peripheral groove, which is formed in the lateral surface of the recess, before the two coupling parts are connected, so that the inner contour of said locking member initially projects out of the second peripheral groove into the cross-section of the recess. In order to facilitate radial expansion when the two coupling parts are connected, it is possible for the cross-section of the projection to be tapered, preferably tapered in a conical and/or rounded manner, at the edge of the projection which faces the base of the recess when the coupling parts are joined together. The tapered portion, which is for example conical, effects force transmission that facilitates the radial expansion of the locking member, depending on the cone angle, so that only a comparatively low axial force is required for assembling and for connecting the two coupling parts, depending on the specific configuration. Secondly, the level of the axial force which is required to then disconnect the two coupling parts depends on the cross-sectional shapes of the two peripheral grooves and of the locking member. It is preferred for the axial force required to disconnect the coupling parts to be greater in magnitude than the axial connecting force, this being achieved by suitable configuration of the coupling parts and explained in greater detail in the text which follows. Said tapered portion may preferably extend as far as an edge cross-section or edge diameter of the projection, this corresponding approximately to or being slightly smaller than the smallest cross-section or cross-sectional diameter of the projection which is left by the first peripheral groove. In a preferred configuration in which the projection and the recess have a circular cross-section and the periphery of the locking member at least substantially follows a circular contour, provision may be made, in the unloaded state of the locking member, for the outside diameter of said locking member to be less than the diameter of the second peripheral groove at the groove base of said groove, and to be greater than the diameter of the recess. This provides a sufficient gap, in particular an annular gap, in the second peripheral groove, firstly radially outside the locking member, so that the locking member can expand to the necessary degree during the process of connecting the coupling parts. Secondly, the locking member is held in the second peripheral groove in a captive manner as early as after being inserted into said second peripheral groove. It is further preferred that, in the unloaded state of the locking member, the inside diameter of said locking member corresponds to or is slightly greater or less than the diameter of the first peripheral groove at the groove base of said groove. This has the effect that the circlip or locking ring is located in the first peripheral groove without appreciable radial force when no axial force acts on the coupling parts. Secondly, direct transfer of force is achieved in the event of the circlip or ring being accommodated in this way with virtually no radial play. It is also preferred that, at least in the state in which the two coupling parts are connected, the inside diameter of the locking member corresponds to the diameter of the first peripheral groove at the groove base of said groove, and the outside diameter of the locking member is greater than the diameter of the recess. The abovementioned, preferred features have the result that the axial force required to connect the two coupling parts is smaller in magnitude than the axial disconnection force. A plug-type coupling of this type is therefore preferably suitable for applications in which assembly is to be performed in the simplest manner possible and with as little force as possible, but on the other hand the resiliently elastic snap-action connection or locking which serves for connection purposes is to sustain certain axial forces which occur during operation without the connection coming apart. Applications of this type can be found, for example, in the drive of worm conveyors or worm gears, or, for example, also in obliquely toothed gear mechanisms. Even if the above-described cross-sectional shapes and diameters of the first and second peripheral grooves and of the locking member are preferred embodiments, it goes without saying that a wide variety of modifications of these embodiments are also possible within the scope of the invention. For example, it is possible to form the cross-sectional shape of the first peripheral or annular groove to be angular, in particular with rounded portions or chamfers provided in the corners and/or to form the cross-sectional shape of the second peripheral or annular groove to be round. 
         [0008]    According to a further aspect, it is also preferred for, on the first coupling part, the projection to extend from a connection end, which is preferably in the form of a disk and can serve for connection to a drive-side or output-side shaft end, with its lateral surface concentric with the geometric axis of rotation, that is to say with the longitudinal or rotational axis of the coupling. As an alternative, extension of the projection, and accordingly also of the recess, parallel to and at a spacing from the said rotational or center axis, that is to say in an eccentric manner, would also be possible. In conjunction with an eccentric recess, which has a matching cross-section, an eccentric projection of the above type also forms an eccentric driver, the positively-locking connection of which can be used to transmit torque. This means that an eccentric projection of this type, in conjunction with an eccentric recess, would be suitable both for releasable axial connection of the coupling parts and also, by performing a double function, for transmitting torque. Torque transmission by means of the projection and the recess, which have the peripheral groves, would also be possible by said projection and said recess being formed centrally in relation to the center axis but in each case having a mutually matching non-round cross-section, for example an oval, polygonal or angular cross-section. If the cross-section of the projection and the recess deviates from a circular shape, the peripheral profile of the peripheral grooves may deviate from a circular line and to this degree be matched to the peripheral profile of the projection and recess in a suitable manner. The ring-like locking member may also be matched to this, that is to say may have, for example, an oval, polygonal or angular peripheral profile in the unloaded state. 
         [0009]    However, it is preferred within the scope of the invention for a separate eccentric projection and a separate eccentric recess to be provided for transmitting torque. It is possible for one of the coupling parts to have at least one eccentric projection which extends parallel to and at a spacing from the axis of rotation of the coupling, and for the other coupling part to have at least one eccentric recess for accommodating the eccentric projection, it being possible for the eccentric projection and the eccentric recess to be assigned to the first and second coupling parts in different ways. It is possible for the cross-sections of the eccentric projection and of the eccentric recess to be matched to a common clearance or transition fit as a result of which virtually play-free torque transmission in both directions of rotation is possible. It is also preferred for the two cross-sections of the eccentric projection and the eccentric recess to be bounded in a circular manner, or, for example, in an oval, polygonal or similar manner, transverse to the axis of rotation of the coupling, so that edges are avoided and also high torques can be transmitted without damage. It goes without saying that it is also possible for a plurality of such eccentric projections and a plurality of matching eccentric recesses to be provided for transmitting torque. A possible alternative to a separate eccentric projection and a separate eccentric recess can be seen by there being, for torque transmission, a separate rotary positively-locking projection and a matching rotary positively-locking recess, said rotary positively-locking projection and rotary positively-locking recess having a cross-section which deviates from a circular shape and therefore not necessarily being disposed eccentric to the center axis or rotation axis of the coupling for torque transmission purposes. An oval, polygonal or, under certain circumstances, also an angular cross-section are possible. A preferred configuration can be seen when the eccentric projection or rotary positively-locking projection extends starting from the tapered edge of the, in particular concentric, projection which has the first peripheral groove, and the eccentric recess or rotary positively-locking recess extends starting from the base of the, in particular concentric, recess which has the second peripheral groove. As a result, the snap-action connection or locking is first produced when the eccentric projection or rotary positively-locking projection enters the eccentric recess or rotary positively-locking recess. The first and the second coupling part may be matched to flanges or the like in a variety of ways for connection to drive or output elements, for example shafts with a solid or hollow cross-section. The first coupling part can preferably have a disk-like connecting flange, from which the projection with the peripheral groove rises. The second coupling part can preferably have a central hole, which opens into the recess, for accommodating and fixing, possibly, an (output) shaft in the case of a bell or cup-like overall design. 
         [0010]    The invention also comprises a worm for a conveyor, preferably for a sampler, with the worm flight being fixed to a worm shaft that runs centrally in the longitudinal direction, and the worm shaft being connected to a coupling part of the coupling according to the invention, preferably to the second coupling part of said coupling. Furthermore, the invention comprises a sampler which comprises a worm conveyor that has a worm of the abovementioned type. In this respect, a worm of this type or a sampler of this type may also form the subject matter of independent claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0011]    The invention will be explained in greater detail below with reference to the accompanying figures which show preferred exemplary embodiments of the invention, and in which: 
           [0012]      FIG. 1  shows a longitudinal section through the coupling according to the invention, according to a preferred embodiment in the connected state; 
           [0013]      FIG. 2  shows a section along section line II-II in  FIG. 1 , 
           [0014]      FIG. 3  shows a plan view of the locking member illustrated in  FIG. 1 ; 
           [0015]      FIG. 4  shows a sectional view along section line IV-IV in  FIG. 3 ; 
           [0016]      FIG. 5  shows a further longitudinal section of the coupling shown in  FIG. 1 , at the beginning of the connection procedure; 
           [0017]      FIG. 6  shows a further longitudinal section of the connecting procedure, at a later point in time; 
           [0018]      FIG. 7  shows a perspective view of the coupling according to  FIGS. 1 to 6  in conjunction with a conveyor worm; 
           [0019]      FIG. 8  shows the position from  FIG. 7  from another viewing direction; 
           [0020]      FIG. 9  shows a longitudinal section of the components shown in  FIGS. 7 ,  8  in the connected state; and 
           [0021]      FIG. 10  shows a preferred application example of the coupling shown in  FIGS. 1 to 6  in a sampler with a conveyor worm. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0022]      FIG. 1  shows a longitudinal section of a preferred exemplary embodiment of the coupling  1  according to the invention, said longitudinal section running through the central geometric axis of rotation  2  of said coupling. The coupling  1  comprises a first coupling part  3  and a second coupling part  4 , these coupling parts each being integrally formed. In this case, the first coupling part  3  has a shape which is formed from a plurality of disk segments, so that it could also be called a coupling disk. In contrast, the second coupling part has inner recesses that adjoin one another, the cross-sections of which are matched to the disk segments, so that this can be called a coupling bell overall. On the first coupling part  3 , the disk segment  5  of largest diameter which is axially at the edge forms a connecting flange for connection to a matching mating flange of a drive or output element, preferably to a drive flange. To this end, two through holes  9 , which are opposed and at the edge and through which screws  10  are brought in order to be screwed into the thread of the mating flange (cf.  FIG. 10 ), are located at that edge  8  which projects beyond the adjoining disk segments  6 ,  7 . In addition, a central through hole  9  is provided with a screw  10 , the screw head of said screw being recessed into the disk segments  6 ,  7  of reduced diameter. For the purpose of connection to a drive or output element, preferably for connection to an output-side hollow shaft  11  which is illustrated by way of a detail of an end, the second coupling part  4  has a central through hole  12  which extends as far as said recesses. In the selected exemplary embodiment, the three disk segments  5 ,  6  and  7  each have a circular cross-section, with the diameter in each case being reduced from disk segment  5  to disk segment  6  and from there to disk segment  7 . In this respect, the central disk segment  6  forms a projection  13  which extends in the direction of the geometric axis  2  from the connecting segment  5 , with a first peripheral groove  15  with a semicircular cross-section (also see  FIGS. 5 and 6 ) being let into in the cylindrical outer surface  14  of said projection  13 . In the selected example, but not necessarily, the peripheral groove is a closed or continuous annular groove of circular shape on the periphery. The second coupling part  4  has a recess  16 , the similarly round cross-section of which is adapted as a receptacle for the projection  13  with a clearance or transition fit and into the cylindrical lateral surface  17  of which a second peripheral groove  18  is made. In the selected example, but not necessarily, the peripheral groove is also here an annular groove which runs in a circular and closed manner on the periphery. In terms of their lateral surfaces  14 ,  17 , the projection  13  and the recess  16  are disposed concentric with the center line  2 . In the connected state shown in  FIG. 1 , the two coupling parts  3 ,  4  can be releasably connected in a resilient and latching manner by means of a locking member  19  which is inserted into the two peripheral grooves  15 ,  18  in the axial direction, that is to say in the direction of the axis of rotation  2 . As illustrated in  FIGS. 3 ,  4 , the locking member is a spring-steel round-wire circlip which is open on the periphery. While the first peripheral groove  15  has a semicircular cross-sectional shape transverse to its peripheral direction (cf.  FIG. 5 ), the second peripheral groove  18  has a rectangular cross-sectional shape, being virtually square in the selected exemplary embodiment. On its cross-section which is oriented transverse to the peripheral direction, the locking member  19  has a cross-sectional radius r which corresponds to the radius R of the rounded portion of the first peripheral groove  15 . The width B of the second peripheral groove  18  in the axial direction is only slightly (and in the figures therefore not visibly) greater than the diameter d of the cross-section of the locking member  19 . The function of this releasable axial coupling or locking device which is formed from the projection  13  with a peripheral groove  15 , the recess  16  with a peripheral groove  18  and the locking member  19 , will be discussed in even greater detail in the text which follows. 
         [0023]    With reference to  FIGS. 1 and 2 , it is also clear that the first coupling part  3  has an eccentric projection  20  which is formed by the disk segment  7  of smallest diameter. As shown in  FIG. 2 , this eccentric projection extends with the eccentricity e parallel to and at a spacing from the axis of rotation  2  of the coupling. The second coupling part  4  has an eccentric recess  21 , which is matched to the eccentric projection  20  with a clearance or transition fit, in order to accommodate the eccentric projection  20 . The eccentric projection  20  extends starting from a tapered edge of the projection  13  that has the peripheral groove  15 , and the eccentric recess  21  extends starting from the base of the concentric recess  16  that has the second peripheral groove  18 . In this respect, the eccentric projection  20  and the eccentric recess  21  form a positively-locking, releasable torque transmission device. 
         [0024]    The round-wire circlip shown in  FIGS. 3 ,  4  has, in the unloaded state, an open periphery which follows a circular line. In the selected example, the width X of the peripheral opening is approximately ¼ of the inner ring diameter D 2 . 
         [0025]    Bringing in  FIGS. 5 and 6 , the functioning of the axial connection device and the establishment and release of the axial coupling connection will now be described in greater detail.  FIG. 5  relates to a first state in which the two coupling parts  3 ,  4  are not yet locked in the axial direction. The locking member  19  is initially inserted into the peripheral groove  18  of the coupling part  4  such that it can still move. In this unloaded state of the locking member  19 , the outside diameter D 1  of said locking member is less than the diameter D 3  of the second peripheral groove  18  at the groove base of said peripheral groove, but is greater than the diameter D 4  of recess  16 , so that the result is captive accommodation, and the inner contour of the locking member  19  protrudes out of the peripheral groove  18  (at least by way of a portion of its periphery, depending on the exact position) radially inward into the recess  16 . In order to connect the two coupling parts  3 ,  4 , the projection  13  is initially inserted into the recess  16  as far as an axial depth which is somewhat less than that in  FIG. 5 , and the coupling parts  3 ,  4  are rotated in relation to one another until the eccentric projection  20  enters the eccentric recess  21 . The position shown in  FIG. 5  in which the conical tapered portion  22  of the projection  13  butts, by way of its edge or transition to the eccentric projection  20 , against the round-wire circlip  19  is only reached as a result of the above action. In the selected example, the cone angle of the tapered portion  22  is, by way of example, 30°, but, in a deviation from this, other cone angles and/or rounded portions can be realized. The coupling part  3  can be pushed further into the coupling part  4  by applying an increased axial force. In the process, the tapered portion  22  widens the locking member  19  to such a degree that said locking member can move up onto on the lateral surface  14 , cf.  FIG. 6 . Upon further insertion, the connection state in  FIG. 1  is reached, in which the locking member  19  latches into the radially inner peripheral groove  15  on account of its spring action and radial prestress. In this connection state, the inside diameter D 2  of the locking member  19  corresponds to the diameter D 5  of the first peripheral groove  15  at the groove base of said peripheral groove, and the outside diameter D 1  of the locking member  19  is greater than the diameter D 4  of the recess  16 . On account of the described size and diameter ratios, one half of the cross-sectional shape of the round-wire circlip  19  is situated in each of the annular grooves  15 , 18  in the selected exemplary embodiment. Furthermore, in the unloaded state of the locking member  19  also, the inside diameter D 2  of said locking member  19  corresponds to the diameter D 5  of the first peripheral groove  15  at the groove base of said peripheral groove in the selected exemplary embodiment. Disconnection of the coupling parts  3 ,  4  is effected in analogous manner by reversing the relative displacement, an axial force of greater magnitude being required however for this purpose in the desired manner on account of the selected cross-sections of the annular grooves and of the round-wire circlip.  FIG. 1  also shows that the axial position of the first and second peripheral grooves  15 , 18  is selected or determined such that the projection  13  and the eccentric projection  20  virtually completely fill the associated recesses  16 ,  21  in the connection state shown, but with a small axial gap remaining at the end, and also at the flange  8 , in order to avoid any problems. 
         [0026]      FIGS. 7 to 9  show the coupling  1  described with reference to the preceding figures in conjunction with a worm  23  which serves to convey, for example, bulk materials. The worm comprises a worm flight  24  which is fixed in a manner which is known per se on a central worm shaft  25  of hollow cross-section. At the drive end, the worm shaft  25  enters the hole  12  (cf.  FIG. 1 ) of the second coupling part  4  and can be secured, for example welded, (in a manner which is not illustrated in greater detail) to the coupling part  4  in the axial direction and the peripheral or rotational direction. In this respect, the worm  23  is further developed, according to the invention, such that it is connected to the second coupling part  4  and to the coupling  1  according to the invention. 
         [0027]      FIG. 10  shows, in a longitudinal section which is schematically simplified in part, a preferred application example, which lies within the scope of the invention, of the coupling or worm according to the invention which is described with reference to the preceding figures. The apparatus shown is what is known as a sampler, in which the worm  23  which is described with reference to  FIGS. 7 to 9  serves to feed loose sample material, such as for example cement, to a mixer  27 . A geared motor  28  drives a mixer agitator  29  and, via this, the worm shaft  25  by means of the axially interpositioned coupling  1  according to the invention. The sample material, for example cement, falls into a chute  30  (conveying with negative pressure) and passes through sample-capturing openings  31  into a casing pipe  32  and, in said casing pipe, into conveying spaces in the worm  23 . The openings  31  may be, for example, round, elliptical, angular or in the shape of elongate slots and be axially parallel (or not) depending on the position. A cement sample is conveyed by the worm  23  in the casing pipe  32  into the mixer  27  by rotating the worm shaft  25 . A pneumatic cylinder  33  closes a sample discharge  35  of the mixer  27  by way of the closure plunger  34 . During sampling, the mixer agitator  29  thoroughly mixes the cement sample in the mixer  27 . If the mixer  27  is over-filled, the sample material is conducted to the outlet  38  through the overflow  36  and the overflow channel  37 . A sample can be taken from the mixer  27  either by means of the device for manual sampling  39  or through the sample discharge  35 . The plug-type coupling  1  according to the invention allows the worm  23  to be coupled to and uncoupled from the mixer  27 , and in particular also allows retrofitting of said worm to said mixer. In the selected exemplary embodiment, the second coupling part  4  (that is to say the coupling bell) is connected to the worm shaft  25  such that it cannot be released. The worm itself is welded to the worm shaft. For mounting or connecting purposes, the first coupling part  3  (or the coupling disk) on the mixer agitator  29  is located on the drive shaft of the geared motor  28 , or is mounted there on a once-off basis. In the second coupling part  4 , the round-wire circlip (locking member  19 ) is inserted into the peripheral groove  18  in said coupling part. The worm  23  is inserted, with the worm shaft  25  and the coupling bell  4 , in the axial direction through a mixer flange  41  and the connection pipe  40  (guide pipe), and the second coupling part  4  is pushed onto the first coupling part  3  in a centering manner until the desired coupling connection is established in the manner described above. In this case, it is possible to sense the position of the eccentric projection  20  by rotating the worm  23  and then to bring the coupling  1  into latching engagement by gentle pressing, for example by striking the worm with a plastics hammer. The plug-type coupling  1  can be released again by pulling strongly on the worm  23 . In the manner described, the worm can also be coupled to and uncoupled from the mixer, for example for cleaning purposes, any number of times in the described simple and space-saving manner, even though the drive-side shaft end is accessible only through the narrow connection pipe  40 . The casing pipe  42  can be fixed to the mixer by way of a casing pipe flange  43  and the mixer flange can be firmly screwed to the guide pipe. A further casing pipe flange  44  is used to attach the casing pipe to a mating flange  45  which is screwed to the chute  30 . This construction makes clear that the worm  23  can be coupled and uncoupled after removal of the chute  30  even with the casing pipe  42  fitted. On account of the worm conveying direction selected in  FIG. 8 , an axial force which is directed away from the coupling  1  acts on the worm  23  during operation. The locking device of the coupling  1  is provided in the above-described manner such that it can withstand the axial force during operation but on the other hand the coupling  1  can still be manually released. 
         [0028]    All disclosed features are (in themselves) pertinent to the invention. The disclosure content of the associated/accompanying priority documents (copy of the prior application) is also hereby incorporated in full in the disclosure of the application, including for the purpose of incorporating features of these documents in claims of the present application.