Abstract:
A thinner shoe mounted receptacle results from a thin cleat attachment flange received in a shallow receptacle cavity. An angled interface between the cleat and receptacle provide a friction fit engagement to minimize inadvertent disengagement of the cleat and receptacle. Rotational locking occurring inside or outside the cavity further prevents inadvertent cleat rotation. Multiple positionally synchronized angular stops positively define the final angular orientation of the cleat in the receptacle.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims priority from U.S. Provisional Patent Application Ser. No. 61/168,245 entitled “Low Profile Cleat and Receptacle Assembly and Attachment Method,” filed Apr. 10, 2009. The disclosure in that provisional patent application is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND 
     1. Technical Field 
     The present invention pertains to an improved method and apparatus for interconnecting traction cleats and cleat receptacles for athletic shoes. Although the preferred embodiments disclosed herein are used primarily in golf shoes, it is to be understood that the interconnection method and structure have application in any shoe that utilizes traction cleats that are selectively attachable to a shoe. 
     2. Terminology 
     It is to be understood that, unless otherwise stated or contextually evident, as used herein: 
     The terms “upper”, “top”, “lower”, “bottom”, “vertical”, “horizontal”, etc., are used for convenience to refer to the orientation of a cleat and receptacle when attached to a shoe sole resting on the ground and are not intended to otherwise limit the structures described and claimed. 
     The terms “axial”, “axially”, “longitudinal”, “longitudinally”, etc., refer to dimensions extending parallel to the axis about which the cleat is rotated in the receptacle and substantially perpendicular to the shoe sole. 
     The terms “radial”, “radially”, “lateral”, “laterally”, etc., refer to dimensions extending perpendicularly from the cleat rotational axis and substantially parallel to the shoe sole. 
     The terms “angle”, “angular”, “rotationally”, etc., unless otherwise stated refer to rotation dimension about the cleat rotational axis. 
     The terms “attach”, “attachment”, etc., pertain to a longitudinal engagement between the cleat and receptacle that prevents inadvertent axial displacement of the cleat relative to the receptacle. 
     The terms “lock”, “locking”, etc., pertain to preventing inadvertent rotational movement between the attached cleat and receptacle. 
     3. Discussion of the Prior Art 
     Replaceable traction cleats are designed to attach and lock into receptacles embedded in the outsole of a shoe. Typically, attachment is effected by means of a threaded stem extending from the top surface a cleat hub and engaging a correspondingly threaded socket in a shoe-mounted receptacle. The engaged thread surfaces provide the attachment by preventing longitudinal movement between the stem and socket. Examples of such an arrangement may be found in U.S. Pat. No. 5,036,606 (Erich), U.S. Pat. No. 6,272,774 (Kelly), U.S. Pat. No. 6,305,104 (McMullin), U.S. Pat. No. 6,823,613 (Kelly et al), U.S. Pat. No. 6,834,446 (McMullin), U.S. Pat. No. 7,107,708 (Kelly et al) and U.S. Pat. No. 7,137,213 (Kelly et al). Examples of other cleats that are useable in such arrangements may be found in U.S. Pat. No. 6,305,104 (McMullin), U.S. Pat. No. 6,675,505 (Terashima), U.S. Pat. No. 7,040,043 (McMullin). The entire disclosures in all of those patents are expressly incorporated herein by this reference. The receptacles used in the interconnection arrangements disclosed in the aforesaid patents necessarily have a relatively large longitudinal (i.e., vertical) profile in order to accommodate the longitudinal space needed for: (a) the threaded engagement between the receptacle and cleat stem; and (b) the locking components provided on the receptacle and cleat that gradually engage as the stem is rotated further into the socket and prevent inadvertent loosening of the interconnection between these two components. Typically, the receptacles in these arrangements have a longitudinal dimension on the order of 6 mm or greater. This dimension of the receptacle dictates a minimum thickness of the outsole of the shoe in which the receptacle is embedded. It is desirable that the receptacle be shorter in length in order to permit a thinner and less costly outsole, and because many golfers desire a thinner outsole to improve their feel for the terrain. 
     In order to prevent inadvertent rotation of the cleat stem relative to the socket, it is known to provide a locking arrangement such as that disclosed in the Kelly &#39;774, Kelly, &#39;613, Kelly et al &#39;708 (Kelly et al) and Kelly et al &#39;213 patents. These locking arrangements typically include teeth projecting radially from the socket exterior on the receptacle which increasingly engage, as a function of axial insertion of the stem, locking posts, or the like, projecting longitudinally from the cleat hub in spaced relation to the threaded stem. 
     The attachment arrangement shown in U.S. Pat. No. 5,768,809 (Savoie), instead of attaching the cleat and receptacle by using a threaded stem to engage a correspondingly threaded socket for engagement, has a post with three radially extending retaining members at its distal end. The retaining members are received axially through retainer-matching contoured openings in a receptacle cavity end wall and rotated in the cavity to an angular position past the contoured openings in which the cavity end wall prevents longitudinal movement of the retaining members. Locking structures within the cavity and at the radial extremities of the retaining members are engaged to minimize inadvertent rotational movement of the retaining members. In order to maximize retention in the cavity, the retainer members are relatively thick in their longitudinal dimension to minimize retaining member distortion under stress. Commercial embodiments of this arrangement are sold under the Q-LOK trademark and have retaining members with a vertical thickness of approximately 3 mm at their thickest part. The receptacle cavity must be sufficiently deep to receive the retainer members, which typically requires that the overall receptacle longitudinal dimension be at least 6 mm. As noted above, this dimension of the receptacle dictates a minimum thickness of the outsole of the shoe in which the receptacle is embedded and it is desirable that the receptacle be made thinner in length in order to permit the outsole to be thinner, thereby making it less costly to manufacture and providing the golfer with a better feel for the terrain. 
     It has been found that reliability of the locking arrangement for the attachment structure disclosed in the aforesaid Savoie patent leaves something to be desired. Specifically, the post and retaining members are a relatively rigid unitary structure, and the outer peripheries of the retaining members are flush against the cavity periphery. As a consequence, lateral forces during use are applied directly through the cavity wall to the unitary post and retaining members, tending to jar and loosen that unitary structure, displacing it from its locking structure in the cavity and permitting it to rotate in the cavity. 
     In other prior art locking arrangements the rotationally locked position of the cleat relative to the receptacle may be imprecise, depending on manufacturing tolerances or inherent features of the design. It is desirable to assure that locking structures on the cleat and receptacle provide for precision and reliable locking in desired rotational orientations of cleat relative to the receptacle. 
     Early golf cleats attached to a receptacle in the sole of the shoe using standard screw threads on a stem and in a socket requiring as many as ten 360° revolutions to secure the cleat in the receptacle against the outsole. Attempts at locking involved compressing the top of the cleat hub against the outer surface of the outsole to effect a friction fit. However, in practical use, this friction fit did not prevent the cleat from backing itself out from over time. In addition, there was no specific stopping point which alerted the installer of the cleat that the stem had been screwed in far enough; that is, there was no “stop” and no visible, audible or tactile indication that full insertion had been achieved. 
     OBJECTS AND SUMMARY OF THE INVENTION 
     Therefore, in light of the above, and for other reasons that become apparent when the invention is fully described, it is one object of the present invention to provide improved attachment and locking methods and apparatus between a traction cleat and a shoe-mounted receptacle. 
     It is another object of the invention to provide an improved cleat and a receptacle therefor for use in an athletic shoe, and to provide an athletic shoe employing said combination. 
     A further object of the invention is to provide an improved traction cleat for an athletic shoe. 
     A still further object of the invention is to provide an improved receptacle adapted to be mounted in an athletic shoe to receive a traction cleat. 
     Another object of the invention is to provide, in combination, an athletic shoe in combination with an improved receptacle for receiving a traction element. 
     It is also an object of the invention to provide an attachment arrangement between a cleat and receptacle that is configured to permit minimization of the longitudinal profiles of the cleat and the receptacle, individually and in combination. 
     Another object of the invention is to provide locking arrangements between a cleat and receptacle configured to permit minimization of the longitudinal profiles of cleat and the receptacle, individually and in combination. 
     It is another object of the present invention to provide attachment and locking apparatus and methods between a traction cleat and a receptacle wherein the receptacle longitudinal dimension can be minimized. 
     It is another object of the present invention is to provide plural positionally synchronized locking apparatus and methods between a cleat and receptacle to assure positive locking in a predetermined rotational position of the cleat. 
     A further object of the invention is to provide locking apparatus and methods between a cleat and receptacle that provide a cleat installer with positive humanly perceptible feedback upon insertion of the cleat to the desired position in the receptacle. 
     The aforesaid objects are achieved individually and in combination, and it is not intended that the present invention be construed as requiring two or more of the objects to be combined unless expressly required by the claims attached hereto. 
     With the foregoing objects in mind, in accordance with one aspect of the invention a receptacle is provided having a total height of 5 mm or less and preferably approximately 3 or 4 mm. In one embodiment of the invention an attachment structure for a traction cleat includes a connection stem projecting upwardly from a cleat hub concentrically about the cleat attachment axis and first and second 180°-spaced relatively thin attachment flanges extending radially from the distal end of the stem. A receptacle cavity or socket is defined concentrically about a receptacle attachment axis by a hollow generally cylindrical boss projecting downwardly from a base with a distal end wall having apertures contoured to permit passage of the cleat attachment flanges when the cleat stem is inserted into the cavity in an insertion angular orientation with the cleat and receptacle attachment axes in coaxial orientation. The bottom surface of each attachment flange and a respective section of the interior surface of the distal end wall of the boss are correspondingly arcuately sloped or ramped about the attachment axes such that, in response to rotation of the flanges in the cavity about the attachment axes, an increasingly tighter friction or interference fit is created between the flange and the proximal and distal end walls of the cavity. As the rotation continues each flange contacts a respective rotational stop member in the cavity defining a final angular or rotational orientation of the cleat relative to the receptacle, in which position the cleat is locked in the receptacle in the manner described herein. The interference fit between the flange and cavity end walls opposes inadvertent rotation of the flange and thereby provides a first locking function for the cleat in the receptacle. 
     Additional locking is effected radially outward from the receptacle cavity. Specifically, two cleat locking structures, angularly spaced by 180°, also project upwardly from the cleat hub at locations radially spaced from the stem and angularly interleaved between the attachment flanges. The radially inward facing surface of each cleat locking structure has three angularly successive convex ridges separated by two concave recesses. The ridges and recess extend axially the entire vertical height or length of the cleat locking structure. Two receptacle locking clusters, also angularly spaced by 180°, are extend circumferentially on the outer wall of the cylindrical boss angularly interleaved between the contoured openings in the distal end wall. The radially outward facing surface of each receptacle locking cluster has three angularly successive concave recesses bounded by four locking teeth. These teeth and recesses extend axially the entire vertical height or length of the outer surface of the receptacle boss. The locking structures and locking clusters are sized and oriented such that the ridges of the each cleat locking structure radially interferes with the teeth of a corresponding receptacle locking cluster when those ridges and teeth are angularly aligned. Similarly, when the ridges or teeth of a locking structure or cluster are angularly aligned with recesses of the corresponding locking cluster or structure, the ridges or teeth extend into the aligned recesses such that inadvertent rotation of the cleat is resisted by the adjacent interfering ridges or teeth. 
     The top surface of each cleat locking structure slopes downward toward the hub as a function of angular position to define an upwardly facing arcuate ramp surface that curves about the attachment axes. As the cleat stem is rotated in the receptacle socket during cleat installation, the ramp segments on the top sections of the cleat locking structures are gradually compressed against arcuate surface sections of the receptacle to effect a force fit tightening of the cleat in the receptacle. 
     The top surface of the cleat hub is provided with two shallow upwardly extending helical ramp segments spaced from one another by 180° and disposed coaxially about the cleat stem in the arcuate space between the stem and a respective cleat locking structure. The bottom surface of the boss end wall on the receptacle has two corresponding shallow downwardly extending helical ramp segments spaced by 180° and disposed coaxially about the receptacle axis at angular locations between the receptacle locking structures. The radial locations of the ramps on the cleat has them aligned with respective ramps on the receptacle such that as the cleat stem is rotated in the receptacle cavity the aligned arcuate ramps slide along one another in an angled interface that provides a gradually increasing friction or interference engagement. The ramps each terminate in respective radially extending shoulders positioned such that they angularly abut and serve as additional positive rotational stops in the final angular position of the cleat stem relative to the receptacle socket. 
     In the present invention the cleat stem is fully axially inserted in the receptacle cavity prior to its rotation therein, unlike threaded engagements wherein gradual axial insertion is effected by rotation. As the stem and flange are rotated in the cavity, the entire axial length of successive ridges on each cleat locking structure are angularly forced past the entire axial length of successive teeth of the receptacle locking cluster in steps, first one ridge at a time, then two and finally three, at which point the cleat is in the final angular position in the receptacle with the ridges and teeth of each locking structure/cluster residing in recesses of the facing locking cluster/structure. With each step the installer receives both tactile and audible “click” indications. In addition, since more ridges and teeth are engaged during each step, the rotational force required for that step is greater. As a consequence, the installer is made readily aware when a cleat is partially or fully inserted. Since there are two pairs of engaged locking structures and clusters, six ridges and teeth are engaged in the final angular position to provide strong positive rotational locking. 
     Instead of facing one another radially, the ridge/teeth and recesses may be arranged to face and engage one another in the vertical or axial dimension as described in detail hereinbelow. 
     Although the preferred embodiment utilizes two attachment flanges disposed in angular symmetry on the cleat stem, it is to be understood that only one flange or three or more flanges may also be used as described herein. 
     The attachment flanges are described as being “thin” in the vertical dimension. By “thin” it is meant that the tapered flange at its thickest portion has a vertical dimension on the order of 1.5 mm or less. The resistance to flexure lost by making the flange that thin is more than compensated for by the additional locking arrangements described herein, and by the small annular spaces between the stem and cleat locking structures that absorb lateral impact instead of the impact being applied directly to the receptacle boss. A primary benefit of the thin flange is the ability to reduce the vertical dimension of the receptacle. 
     The features described in combination above may also be used independently. For example, the cleat locking structures and receptacle locking clusters may be used with any type of attachment arrangement including a threaded stem and socket. Likewise, the interference fit provided by the mutually engaged helical ramps on the cleat and receptacle may be used with a threaded stem and threaded socket. 
     The above and still further features and advantages of the present invention will become apparent upon consideration of the definitions, descriptions and descriptive figures of specific embodiments thereof set forth herein. In the detailed description below, like reference numerals in the various figures are utilized to designate like components and elements, and like terms are used to refer to similar or corresponding elements in the several embodiments. While these descriptions go into specific details of the invention, it should be understood that variations may and do exist and would be apparent to those skilled in the art in view of the following description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a view in perspective from above of a cleat according to a first embodiment of the present invention. 
         FIG. 2  is a top view in plan of the cleat of  FIG. 1 . 
         FIG. 3  is a front view in elevation of the cleat of  FIG. 1 . 
         FIG. 4  is a side view in elevation of the cleat of  FIG. 1 . 
         FIG. 5  is a bottom view in plan of the cleat of  FIG. 1 . 
         FIG. 6  is a bottom view in plan of a receptacle according to the first embodiment of the invention for receiving the cleat of  FIG. 1 . 
         FIG. 7  is a front view in elevation of the receptacle of  FIG. 6 . 
         FIG. 8  is a side view in elevation of the receptacle of  FIG. 6 . 
         FIG. 9  is a view in perspective from below of the receptacle of  FIG. 6 . 
         FIG. 10  is front view in section of the receptacle taken along lines  10 - 10  of  FIG. 6 . 
         FIG. 11  is a side view in section of the receptacle taken along lines  11 - 11  of  FIG. 6 . 
         FIG. 12  is a view in perspective from below of a receptacle according to a second embodiment of the present invention. 
         FIG. 13  is a bottom view in plan of the receptacle of  FIG. 12 . 
         FIG. 14  is a view in perspective from above of a cleat according to the second embodiment of the invention for engaging the receptacle of  FIG. 12 . 
         FIG. 15  is a top view in plan of the cleat of  FIG. 14 . 
         FIG. 16  is an exploded view is perspective from below of the cleat of  FIG. 14  and receptacle of  FIG. 12 . 
         FIG. 17  is an exploded view is perspective from above of the cleat of  FIG. 14  and receptacle of  FIG. 12 . 
         FIG. 18  is a top view in plan of a cleat according to a third embodiment of the present invention. 
         FIG. 19  is a bottom view in plan of a receptacle according to the third embodiment of the invention for receiving the cleat of  FIG. 18 . 
         FIG. 20  is a top view in plan of a cleat according to a fourth embodiment of the present invention. 
         FIG. 21  is a bottom view in plan of a receptacle according to the fourth embodiment of the invention for receiving the cleat of  FIG. 20 . 
         FIG. 22  is a top view in plan of a cleat according to a fifth embodiment of the present invention. 
         FIG. 23  is a bottom view in plan of a receptacle according to the fifth embodiment of the invention for receiving the cleat of  FIG. 22 . 
         FIG. 24  is a top view in plan of a cleat according to a sixth embodiment of the present invention. 
         FIG. 25  is a bottom view in plan of a receptacle according to the sixth embodiment of the invention for receiving the cleat of  FIG. 24 . 
         FIG. 26  is a view in perspective from above of a cleat according to a seventh embodiment of the present invention. 
         FIG. 27  is a view in perspective from below of a receptacle according to the seventh embodiment of the invention for receiving the cleat of  FIG. 26 . 
         FIG. 28  is a view in perspective from above of a cleat according to an eighth embodiment of the present invention. 
         FIG. 29  is a view in perspective from above of a cleat according to a ninth embodiment of the present invention. 
         FIG. 30A  is an exploded view in perspective from below showing the cleat of  FIG. 28  in combination with a receptacle for receiving that cleat. 
         FIG. 30B  is a view in perspective from below of the receptacle of  FIG. 30A . 
         FIG. 31  is a top view in plan of a cleat according to a tenth embodiment of the present invention. 
         FIG. 32  is a view in perspective from above of the cleat of  FIG. 31 . 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The specific angular and linear dimensions set forth below are by way of example for particular embodiments to assist in an understanding of the illustrated structure; these dimensions are not to be construed as limiting the scope of the invention. 
     Referring specifically to  FIGS. 1-11  and the embodiments disclosed therein, a traction cleat  10  comprises a hub  11  with a top surface  12  and bottom surface  13 . The hub is generally circular but can be otherwise configured, symmetrically or asymmetrically about cleat attachment axis A. Ground engaging traction elements  14  extend generally downward from the hub periphery or bottom surface. It is to be understood that particular traction elements do not form part of the present invention and may be provided as static or dynamic elements in any number, array or orientation. In the particular embodiment illustrated in  FIGS. 1-5  there are six traction elements  14  spaced at equal angles in an array that is symmetrical about cleat axis A. 
     A generally cylindrical connection stem  20  may be integrally molded with hub  11  and includes a proximal end and a distal end. Stem  20  projects upwardly from top surface  12  concentrically about cleat attachment axis A. Two vertically thin attachment flanges  23   a ,  23   b  extend generally radially outward from 180°-spaced locations at the distal end of stem  20 . Each flange has a flat leading edge  21  oriented substantially parallel to axis A and angularly facing in the direction of cleat rotation about that axis during cleat insertion into a receptacle. The top surface of each flange  23   a ,  23   b  is co-planar with the distal end of stem  20 . The bottom surface  25  of each flange diverges downwardly and angularly rearward from leading edge  21  to define a flange ramp surface having a curvature about axis A. A vertical space is defined between flange bottom surface  25  and the top surface  12  of cleat hub  11 , such space becoming vertically narrower in an angular direction as a result of the divergence of flange surface  25 . The rearward edge of each flange is preferably flat and parallel to axis A. The flange sides are flat and converge slightly at a small angle, typically 5° to 7°. The radially outer edge of each flange is preferably arcuate. The proximal end of each flange at the periphery of stem  20  subtends an angle at the stem of approximately 80°. In the illustrated embodiment, the vertical thickness of the flange at its thickest portion is approximately 1.5 mm. 
     There are two locking structures  30   a ,  30   b , spaced by 180° (on center) and standing upwardly from the top surface  12  of hub  11  proximate the hub periphery. Each locking structure includes a substantially smooth and arcuate radially outward facing surface  35 , a leading end  36 , a trailing end  37  and an undulating radially inward facing surface which serves to provide a cleat locking function. Leading end  36  is a substantially planar (i.e., flat) radially and vertically extending surface facing angularly in the direction of rotation during cleat insertion. Trailing end  37  is arcuate and forms part of a ridge as described below. Each locking structure extends about axis A through an angle on the order of 74°. 
     The inward facing surface of each locking structure includes an angularly extending series of three convex ridges  41 ,  42 ,  43  projecting radially inward toward axis A and separated by concave recesses  44  and  45  disposed between ridge pairs  41 ,  42  and  42 ,  43 , respectively. The ridges and recesses extend lengthwise the entire height of structures  30   a ,  30   b . The angular contour of the series of the ridges and recesses is continuous and smooth to provide locking ramp surfaces having slopes appropriate to the locking functions. The apex of each ridge  41 ,  42 ,  43  is preferably rounded with a larger radius of curvature than the radius of curvature of the nadir of recesses  44 ,  45 . As best illustrated in  FIG. 2  wherein leading edge  36  is at the counterclockwise end of structures  30   a ,  30   b , the leading ramp of ridge  42  extending from the nadir of recess  44  has a shallower slope than the trailing ramp of ridge  41  extending from the nadir of recess  44 . Likewise, the leading ramp of ridge  42  extending from the nadir of recess  44  has a shallower slope than the trailing edge of ridge  41  extending from the nadir of recess  44 . In the illustrated embodiment, relative to a radial line between axis A and the nadir of each recess, the leading ramp of each ridge subtends an angle of approximately 30° and the trailing ramp subtends an angle of approximately 40°. The apex of each ridge extends sufficiently far inward to contact locking structure teeth on the receptacle described below during insertion of the cleat in that receptacle. In this regard, the locking structure must be made of a material that permits it to resiliently flex or distort radially outward somewhat to permit ridges  41 ,  42 ,  43  to be forced angularly past the interfering receptacle teeth during cleat insertion into the receptacle. 
     The top surface  46  of each locking structure slopes downward toward the hub top surface  12  as a function of angular position from leading edge  36  to trailing edge  37 . As a result, leading ridge  41  is axially longer (i.e., taller) than middle ridge  42  which, in turn, is axially longer than trailing ridge  43 . Top surface  46  serves as a shallow ramp surface which engages a surface on the receptacle described below. 
     The top surface of the cleat hub is also provided with two shallow upwardly extending helical ramp segments  15   a ,  15   b  spaced from one another by 180° and disposed coaxially about axis A in the arcuate space between the stem  20  and a respective cleat locking structure  30   a ,  30   b . The height of the ramp segments increases as a function of angular displacement about axis A in the direction of cleat insertion rotation, and each ramp segment extends angularly approximately 90°. The raised terminal edges of the ramp segments  15   a ,  15   b , respectively, define radially extending shoulders  16   a ,  16   b  serving as rotational stops. These stops are positioned to abut corresponding rotational stop structure on the receptacle, described below, in the final angular insertion position of the cleat. In this regard, the leading edges of flanges  21 , leading ends  36  of the locking structure  30   a ,  30   b , and stops  16   a ,  16   b  are angularly synchronized positionally to contact respective rotation stop structures on the receptacle. 
     A receptacle configured to receive cleat  10  in accordance with the principles of the present invention is illustrated in  FIGS. 6-11  to which specific reference is now made. Receptacle  50  includes a base  51  having a bottom surface  53  and a top surface  52 . The base is generally circular but can be otherwise configured, symmetrically or asymmetrically about receptacle attachment axis B. When cleat  10  is installed in receptacle  50 , cleat axis A and receptacle axis B are coaxially positioned. An outer ring portion of base  51  has a plurality of mounting slots defined longitudinally therethrough for securing the receptacle in a shoe sole. Mounting of the receptacle is effected by methods well known in the art and may include forming the outsole material around the mounting slots, or compression molding as disclosed in U.S. Pat. No. 6,248,278 (Kelly), etc. A generally cylindrical hollow boss  54  is provided centrally on the base and defines a hollow generally cylindrical interior or cavity  55  disposed concentrically about the receptacle longitudinal axis B. The distal end wall  56  of the boss has a contoured aperture  57  defined therethrough to provide access to the cavity. Aperture  57  is contoured to receive, and preferably match, the contour of the distal end of cleat stem  20  and its two attachment flanges  23   a ,  23   b . Specifically, aperture  57  has a central portion configured to receive stem  20  from which two radially extending flange-receiving sections project. The longitudinal depth of cavity  55  is slightly greater than the maximum longitudinal thickness of the cleat attachment flanges  23   a ,  23   b  so that the entire thickness of the flanges can be received within the cavity. Two shoulder stops  65  extend radially inward from the cavity periphery, and longitudinally across the depth of the cavity, to serve as rotational stops for the received flanges during cleat installation. Shoulders  65  are mutually spaced by 180° and each limits the rotation of a respective attachment flange  20  in the cavity to approximately 90° after the flanges have been axially inserted into the cavity through the flange-receiving segments of aperture  57 . The angular positions of shoulders  65  are positionally synchronized with other rotational stops described herein to define the final angular position of the cleat relative to the receptacle. 
     The interior (i.e., upward-facing) surface  66  of each of the two arcuate sections of the boss distal end wall  56 , angularly located between flange-receiving sections of aperture  57 , slopes upwardly in the direction of forward rotation of the flanges during installation. The result is an angular narrowing of the longitudinal depth of the cavity  55  in the installation rotation direction. This narrowing substantially matches the divergence of the undersurface  25  on the attachment flange to provide for a gradually increasing compression of the flange between the boss end walls as a function of the installation rotation angle. Specifically, when surface  66  and undersurface  25  make initial contact during installation rotation, the contact is relatively loose, but as rotation continues the contact becomes gradually tighter and the flanges become more tightly compressed in an axial dimension between the cavity end walls. The result is pulling of the cleat into close engagement with the receptacle, and an interference or friction fit between surface  66  and undersurface  26  that acts in concert with other locking features described herein to prevent inadvertent rotation of the installed cleat. 
     The exposed (i.e., downwardly-facing) surface of boss end wall  56  has two shallow depending helical ramp segments  60   a ,  60   b  spaced from one another by 180° and disposed coaxially about axis B. The longitudinal height of ramp segments  60   a ,  60   b  increases as a function of angular displacement about axis B in the direction of cleat insertion rotation, and each ramp segment has an angular length of between 90° and 180° about the axis. The depending terminal edges of ramp segments  60   a ,  60   b , respectively, define radially extending shoulders  61   a ,  61   b  or rotational stops. Ramp segments  60   a ,  60   b , are positioned to be radially aligned with ramp segments  15   a ,  15   b , respectively, of cleat  10  in an angled interface during cleat insertion. In particular, upon axial insertion of attachment flanges  20  through receptacle aperture  57 , prior to rotation (i.e., in the insertion angular orientation of the cleat and receptacle): the raised terminal ends of cleat ramp segments  15   a ,  15   b  are axially aligned with and abut the starting ends of respective receptacle ramp segments  60   a ,  60   b ; and the starting ends of cleat ramp segments  15   a ,  15   b  are axially aligned with and abut the depending terminal ends of receptacle ramp segments  60   a ,  60   b  in an angled interface. As stem  20  is rotated in cavity  55 , the abutting ramp segments are forced into tighter axial engagement that increases with rotation angle until shoulder stops  16   a  and  16   b  engage respective shoulder stops  61   b  and  61   a . This occurs when the cleat has reached its final angular orientation relative to the receptacle and the frictional engagement between abutting ramp segments is at a maximum. 
     Two angular extending receptacle locking clusters  70   a ,  70   b , angularly spaced by 180°, extend circumferentially on the radially outer wall of the cylindrical boss angularly interleaved between the ramped surfaces  60   a ,  60   b  of the boss distal end wall. For purposes of this embodiment, the angular centers of clusters  70   a ,  70   b , and the angular centers of the flange-receiving sections of aperture  57  preferably reside on a common diametric line extending through axis B. The radially outward facing surface of each receptacle locking cluster has three angularly successive concave recesses  71 ,  72 ,  73  bounded by four teeth  74 ,  75 ,  76 ,  77 . These teeth and recesses extend axially the entire vertical height or length of the outer surface of the receptacle boss. The locking structures are sized and oriented such that the ridges  41 ,  42 ,  43  of each cleat locking structure radially interfere with the teeth  74 ,  75 ,  76 ,  77  of a corresponding receptacle locking cluster when those ridges and teeth are angularly aligned. On the other hand, when the ridges and teeth are angularly aligned with recesses of an aligned locking structure/cluster, the ridges and teeth extend into the aligned recesses such that inadvertent rotation of the cleat is resisted by the adjacent interfering ridges and teeth. In the final angular orientation of the cleat in the receptacle, teeth  75 ,  76  of each receptacle locking cluster reside in recesses  45 ,  44 , respectively, of an aligned cleat locking structure. 
     The leading end  80  of each receptacle locking cluster is the leading edge of tooth  74  and angularly faces the direction of insertion rotation. Leading end  80  has a relatively shallow slope to facilitate it being rotationally passed by the flat radially extending leading end  36  of a cleat locking structure during cleat insertion. Another feature facilitating this passage is the sloped top surface  46  of the cleat locking structure which renders that structure axially longer at leading end  36  and permits the longer end to more readily be flexed about its root at the top surface  12  of hub  11 . The leading edge  81  of trailing tooth  77  is substantially planar (i.e., flat) and extends radially to provide a rotational stop when abutted by substantially planar and flat leading end  36  of the cleat locking structure. 
     Angularly middle teeth  75 ,  76  of the receptacle locking cluster are substantially identical in configuration and taper in an outward direction to a rounded apex. Recesses  44 ,  45  of the cleat locking structure diverge in an inward direction that is substantially the same as the angle of divergence of receptacle teeth  75 ,  76  so that the teeth  75 ,  75  can fit closely in recesses  44 ,  45  in the final or locked angular orientation of cleat  10  in receptacle  50 . 
     An axially short cylindrical wall  84  extends from the base of receptacle  50  concentrically about and outwardly spaced from boss  54  and axis B. Wall  84  and the boss  54  define between them a generally annular space  85  on the bottom surface  53  of base  51  with which the top surface  46  of each cleat locking structure  30   a ,  30   b  is radially and angularly aligned and within which those locking structures fit when stem  20  is inserted into cavity  55 . Upon such insertion ramped top surfaces  46  on the cleat locking structures contact the bottom surface of receptacle base  51  in space  85  and, as the stem is rotated, top surfaces  46  are forced into tighter engagement with base  51  to provide a further friction fit engagement between the cleat and receptacle. 
     In attaching and locking cleat  10  to receptacle  50 , stem  20  and flanges  23   a ,  23   b  are fully axially inserted through aperture  57  into receptacle cavity  55 . As the stem and flanges are then rotated about axes A and B in the cavity, the entire axial length of successive ridges on each cleat locking structure  30   a ,  30   b  are angularly forced past the entire axial length of successive teeth of respective receptacle locking clusters  70   a ,  70   b  in steps: (1) cleat ridge  41  and leading end  36  are rotated past receptacle tooth  74  and into receptacle recess  71  with receptacle tooth  74  projecting into cleat recess  44 ; (2) then cleat ridges  41 ,  42  are rotated past receptacle teeth  75 ,  74 , respectively, and into respective receptacle recesses  72 ,  71 , with receptacle teeth  75 ,  74  projecting into respective cleat recesses  45 ,  44 ; (3) then cleat ridges  41 ,  42 ,  43  are rotated past receptacle teeth  76 ,  75 ,  74 , respectively, and into respective recesses  73 ,  72 ,  71 , with receptacle teeth  76 ,  75  projecting into respective cleat recesses  45 ,  44 , and with leading end  36  of the cleat locking structure abutting leading edge  81  of receptacle trailing tooth  77  to define the final angular orientation cleat  10  in receptacle  50 . With each step the installer receives both tactile and audible “click” indications provided by the ridges and teeth being forced resiliently past one another and into the next recess. In addition, since more ridges are engaged and resiliently deformed during each step, the rotational force required is greater for successive steps. As a consequence, the installer is made readily aware when a cleat is partially or fully inserted. Since there are two pairs of locking structures and clusters, six ridges and teeth are engaged in the final angular position to provide strong positive rotational locking. 
     In the final angular orientation of the cleat and receptacle, axial movement of the cleat relative to the receptacle is prevented by the distal end wall  56  interfering with flanges  23   a ,  23   b  which are not angularly aligned with flange-receiving openings in aperture  57 . 
     From the foregoing it will be appreciated that there are six rotational stops, of three different types, that define the final angular orientation of the cleat and receptacle, in which orientation the cleat is locked in the receptacle by the locking structures and clusters. These stops are: (a) the two cleat shoulder stops  16   a ,  16   b  abutting respective shoulder stops  61   a ,  61   b ; (b) the leading edges  21  of cleat flanges  23   a ,  23   b  engaging respective shoulder stops  65  in cavity  55 ; and (c) the two leading ends  36  of the cleat locking structures engaging stops  81  of the receptacle locking clusters. The cleat and receptacle are constructed such that these stops are synchronized in angular position, meaning that all six stops become engaged at the same angular orientation of the cleat in the receptacle. 
     For some applications it is desirable that the cleat have a particular angular position relative to the shoe sole. For example, the shoe manufacturer may desire that a logo on the cleat have a particular orientation; or the cleat traction elements may differ from one another and specific desired tractional effects are obtained in predetermined angular positions of the cleat. The multiple stops described above predetermine a final or locking orientation of the cleat relative to the initial insertion position. In the situation 
     It will also be appreciated from the foregoing description that there are three separate interference fit or frictional engagements provided that function in addition to the locking structures on the cleat and locking clusters on the receptacle to prevent inadvertent rotation and removal of the cleat from the receptacle. These are: (i) the frictional engagement of each flange undersurface against the interior surfaces  66  of the distal end wall  56  of the receptacle boss  54 ; (ii) the frictional engagement of the angled interface between cleat ramp segments  15   a ,  15   b  and receptacle ramp segments  60   a ,  60   b ; and (iii) the frictional engagement between each top surface  46  of the cleat locking structures and a respective section of the receptacle base in annular section  85  of the base bottom surface  53 . The locking structure and the positive frictional engagements permit a flange of relatively small longitudinal thickness to be utilized without concern about inadvertent unlocking t and removal of the flanges from the receptacle cavity. 
     The angle relative to horizontal of each of the flange undersurface  25  and interior surface  66  of the boss distal end wall is typically greater than the angle relative to horizontal of the engaging ramp segments  15   a ,  15   b  and the boss end wall segments  60   a ,  60   b . Typically, the former is on the order of 4.1° and the latter is on the order of 2.2°. As a result, as the flange is rotated in the cavity it tends to axially drive the ramp segments and end wall segments into more positive engagement to permit the interference fit between them to be more effective. 
     By way of example only, and not to be construed as limiting on the scope of the invention, the following are exemplary dimensions of components of the receptacle: the vertical height of receptacle  50  at its highest point between the bottom surface of the base  51  and the outer surface of distal end wall  56  is 4.0 mm; the nominal angle of the angled interface (that is ramped segments  15   a ,  15   b  and  60   a ,  60   b ) relative to horizontal is approximately 2° with a 1 mm pitch; the nominal angle of the sloped undersurface  25  of the flanges and the abutting interior surface of the boss end wall relative to horizontal is approximately 4° with a 2 mm pitch (approximately twice that angled interface angle and pitch); the angle between each apex of receptacle teeth  75 ,  76  and the radius drawn from axis B through the center of intermediate recess  71  is 14°; the angle between that radius and leading edge  81  of tooth  77  is 35°; the angle between that radius and the leading edge of tooth  75  is 40° (and the angle is similar for the leading edge of tooth  76 ); and the angle between that radius and the trailing edge of toot  75  is 30° (and the angle is similar for the trailing edge of tooth  76 ). 
     As stated above, the vertical thickness of flanges  23   a ,  23   b  of cleat  10  is approximately 1.5 mm. Accordingly, the vertical height of cavity  55  at its longest part, in order to provide the described interference fit, is approximately the same. Typically, that height would be about 1.6 mm or less. 
     It will be appreciated that the differences between the leading and trailing edges of the teeth serve to make it easier to rotate the cleat in the insertion direction (typically clockwise when viewed toward the cleat bottom side) than in the removal direction (typically counterclockwise when similarly viewed. As best illustrated in  FIG. 5 , there are two tool access holes  90  defined in the bottom surface of the cleat at diametrically opposed locations to permit appropriate torque to be applied to the cleat by means of a conventional tool to overcome the locking force and frictional fit engagements. 
     In the embodiment of  FIGS. 1-11  the preferred material for the receptacle is Stanyl  46  Nylon with a Durometer hardness in the range of 88 D-93 D. The preferred material for the cleat hub, stem, attachment flanges and the cleat locking structures is thermoplastic polyurethane (TPU) with a Durometer hardness of between 55 D-75 D and most preferably 71 D. 
     As described above, one of the several advantages of the present invention is the relatively small vertical or axial profile of the assembled cleat and receptacle, and particularly the receptacle which permits it to be installed in a relatively thin shoe outsole. In the embodiment illustrated in  FIGS. 1-11  the receptacle axial profile is approximately 4.0 mm. In the embodiment illustrated in  FIGS. 12-17  the receptacle vertical profile can be made as small as 3.0 mm, a feature made possible by reorienting the locking structure ridges and locking cluster teeth to project vertically (i.e., axially) rather than horizontally (i.e., laterally). In referring to  FIGS. 12-17  it should be noted that, for purposes of simplification, the typical underside of the cleat, which includes the traction elements, is not shown, and that any traction elements can be used. Cleat  110  includes a base  111  having a top surface  112  from which a stem  120  projects upward. Attachment flanges  123   a  and  123   b  extend radially outward from the distal end of the stem. These elements are all similar to the corresponding elements of cleat  10  described above. Likewise, receptacle  150  has boss  154  containing a hollow cavity  155  and a distal end wall  156  with a contoured aperture  157  to receive the cleat stem and attachment flanges. These elements are also similar to corresponding elements in receptacle  50 . In this embodiment the cleat has four locking structures  130   a ,  130   b ,  130   c ,  130   d  that are substantially identical and positioned in angularly spaced relation in an annular array spaced radially outward from stem  120 . It is to be understood that four locking structures are only one example, and that any number of one or more such structures may be provided. Likewise, any number of one or more attachment flanges may be provided. In the illustrated embodiment the flanges  123   a  and  123   b  extend in opposite directions with their angular centers 180° apart and their distal ends extending a radial distance that is smaller than the radial distance of the innermost parts of the locking structures. The angular center of locking structure  130   b  is spaced 60° clockwise from the angular center of flange  123   b  and 60° counterclockwise from the angular center of locking structure  130   c  which is spaced 60° counterclockwise from the angular center of flange  123   a . The angular center of locking structure  130   d  is spaced 60° clockwise from the angular center of flange  123   a  and 60° counterclockwise from the angular center of locking structure  130   c  which is spaced 60° counterclockwise from the angular center of flange  123   b.    
     Each locking structure  130   a ,  130   b ,  130   c ,  130   d  includes three angularly spaced ridges  141 ,  142 ,  143  projecting longitudinally and interleaved with annularly successive recesses  144 ,  145 . Each ridge includes an upstanding support member having a distal end that tapers upwardly to form a radially extending substantially lineal edge which can be rounded, if desired. In the illustrated embodiment the upstanding support members are of rectangular lateral cross-section which is not a limiting feature of the invention. The height of ridges is preferably such that the distal edge is at a lower lateral level than the undersurface of the flanges. Additional requirements for the positioning and configuration of the ridges are described below. 
     Receptacle  150  is provided with a continuous annular array of alternating radially extending teeth  174  and recesses  171 . The array is radially positioned to be aligned with ridges  141  when stem  120  and flanges  123   a ,  123   b  are inserted through aperture  157  into cavity  155 . The ridges are configured to be received in recesses  171  and are sufficiently resiliently flexible to bend and pass over teeth  174  to successive recesses  171  in a ratcheting type engagement as stem  120  is rotated in the cavity. Rotation stop members are provided in the cavity, similar to stop members  65  in receptacle  50 , to limit the rotation of the flanges and define the final angular orientation of the cleat and receptacle. Additional stop members may be provided in angular positional synchronization with the in-cavity stop members in a various functional forms. For example, one or more teeth  174  in the receptacle may be longer than the others to prevent rotation of a ridge past that tooth. 
     Upon full axial insertion of stem  120  and flanges  123   a ,  123   b  into cavity  155 , the ridges and teeth on the locking structures and clusters are fully engaged throughout their radial lengths. During cleat rotation, as each ridge passes a respective tooth into an adjacent recess, the installer us able to audibly and tactilely sense a “click”. 
     The underside of the flanges and the interior surface of the boss end wall are preferably tapered to provide a friction fit as described in connection with cleat  10  and receptacle  50 . Likewise, friction fit mating ramps may provide an angled interface on the exposed outer surface of end wall  156  and the top surface of the cleat between stem  120  and the locking structures  130   a ,  130   b ,  139   c    130   d.    
     The embodiments described above include two substantially identically configured attachment flanges disposed symmetrically about cleat axis A. It is to be understood that the principles of the invention permit any differently configured flanges to be provided in the same cleat, as well as any number of flanges (one or more), and to have the flanges positioned either symmetrically or asymmetrically in relation to the cleat stem. For example,  FIGS. 18 and 19  illustrate an embodiment wherein three attachment flanges are provided. Specifically, cleat  210  includes a hub  211  with a stem  220  projecting upwardly therefrom. Three attachment flanges  223   a ,  223   b ,  223   c  project radially outward from the distal end of the stem and are at successive 60° locations. Three locking structures  230   a ,  230   b ,  230   c  are disposed at respective angular locations intermediate the attachment flanges at a radial spacing from stem  220  that is greater than the radial spacing between the stem and the distal ends of the attachment flanges. The undersurface of each flange slopes such that the flanges taper in thickness angularly in the same manner as flanges  23   a ,  23   b . In this embodiment each cleat locking structure has two ridges  241 ,  242  spaced by a recess  244 . The leading end  236  of the structure, which is the leading edge of ridge  241 , is configured as a flat planar surface extending radially and longitudinally to serve as an angular stop in the manner described for end  36  in cleat  10 . Three 120°-spaced ramp segments  215   a ,  215   b ,  215   c  are located between respective locking structures and stem  220  and terminate in raised shoulder stops  216   a ,  216   b    216   c  respectively. 
     Receptacle  250  includes a base having bottom and top surfaces and an outer ring portion with plurality of sole-mounting slots defined therethrough. A generally cylindrical boss  254  confines a hollow generally cylindrical interior or cavity  255  disposed concentrically about the receptacle longitudinal axis. The distal end wall of the boss has a contoured aperture  257  defined therethrough to receive the distal end of cleat stem  20  and its three attachment flanges  223   a ,  223   b ,  223   c . Three shoulder stops, spaced by 60° may extend radially inward from the cavity periphery, and longitudinally across the depth of the cavity, to serve as rotational stops for the received flanges during cleat installation. The shoulder stops limit the rotation of respective attachment flanges in the cavity to approximately 60° during installation of the cleat in the receptacle. 
     The interior (i.e., upward-facing) surface of each of the three arcuate sections of the boss distal end wall  256 , angularly located between flange-receiving sections of aperture  257 , slopes upwardly in the direction of forward rotation of the flanges during installation. The result is an angular narrowing of the longitudinal depth of the cavity  255  in the installation rotation direction. This narrowing substantially matches the divergence of the undersurface on the attachment flanges to provide for a gradually increasing compression of the flange between the boss end walls as a function of the installation rotation angle. The result is an interference or friction fit that acts in concert with other locking features described herein to prevent inadvertent rotation of the installed cleat. 
     The exposed (i.e., downwardly-facing) surface of the boss end wall  256  may have three shallow depending helical in an angled interface with segments  260   a ,  260   b ,  260   c  successively spaced by 120° and disposed coaxially about the receptacle axis. The longitudinal height of these ramp segments increases as a function of angular displacement about the axis in the direction of cleat insertion rotation, and each ramp segment extends approximately 60° about the axis. The depending terminal edges of the boss ramp define radially extending shoulders or stops  261   a ,  261   b ,  261   c . The boss ramp segments are positioned to be radially aligned with respective ramp segments  215   a ,  215   b ,  215   c  on cleat  210  during cleat insertion and function therewith in the manner described in connection with ramp segments  15   a ,  15   b ,  15   c  on cleat  10  and  60   a ,  60   b ,  60   c  on receptacle  50 . 
     The outer wall of the boss is provided with three clusters of locking teeth and recesses of the type described in connection with receptacle  50  but configured and positioned to match and engage the ridges and recesses in the three locking structures  230   a ,  230   b ,  230   c.    
     In general, installation of cleat  210  in receptacle  250  proceeds in the same manner described for cleat  10  and receptacle  50  except that there are three flange attachments instead of two, three locking structure/cluster engagements instead of two and three frictional fit engagements resulting from abutting ramp segments instead of two. 
     As a further example,  FIGS. 20 and 21  show a cleat  310  and receptacle  350 , respectively. In cleat  310  four attachment flanges  323   a ,  323   b ,  323   c ,  323   d  and four cleat locking structures  330   a ,  330   b ,  330   c ,  330   d  are provided. In addition there are four ramp segments  315   a ,  315   b ,  315   c ,  315   d  having angular stops  316   a ,  316   b ,  316   c ,  316   d  at their ends. These elements are configured and function similarly to their counterpart elements in cleat  10 . In receptacle  350  the end wall of the boss  354  has an aperture  357  configured to receive the four flanges  323   a ,  323   b ,  323   c ,  323   d  in cavity  355 , four clusters of locking teeth and recesses arranged to engage respective locking structured  330   a ,  330   b ,  330   c ,  330   d  and four ramp segments  360   a ,  360   b ,  360   c ,  360   d  and stops at their raised end positioned and arranged to cooperate in an angled interface with ramps  315   a ,  315   b ,  315   c ,  315   d  and angular stops  316   a ,  316   b ,  316   c ,  316   d  in the manner described in connection with cleat  10  and receptacle  50 . 
     Referring to  FIGS. 22 and 23 , the cleat  410  is essentially the same as cleat  10  and is arranged to be received in receptacle  450  which is similar to receptacle  50 . However, instead of there being two angularly separated clusters of locking teeth and recesses on the outer wall of the receptacle boss there is one continuous cluster of successive locking teeth  470  and recesses  472  extending around the entire boss circumference. Upon axial insertion of the stem into the cavity, the receptacle locking teeth and cleat locking ridges are immediately interleaved although stem and flanges can still be axially withdrawn from the cavity. Upon rotation of the stem the flange becomes axially trapped in the cavity by the boss end wall and becomes frictionally engaged in the manner described as in receptacle  50 . 
     Referring to  FIGS. 24 and 25 , the cleat  510  is essentially the same as cleat  10  and is arranged to be received in receptacle  550  which is similar to receptacle  50 . However, instead of the two receptacle locking clusters  570  being angularly centered co-linearly with the angular center of the flange receiving portions of aperture  557 , locking clusters  570  on boss  554  are offset by 90°. In this embodiment, instead of the stem having to be rotated for there to be engagement between the cleat locking structures  530  and the receptacle locking clusters  570 , the locking structures and locking clusters are immediately engaged. In this position the stem  520  and flanges  523  can still be withdrawn from the receptacle cavity. As the stem and flanges are rotated in the cavity, the cleat locking structures  530  rotate past respective receptacle locking clusters until, after approximately 90° of rotation, cleat locking structures  530  and receptacle locking clusters  570  are no longer in angular alignment. Instead the cleat locking structures reside in annular gaps between the receptacle locking clusters and are free to rotationally move within those gaps. This provides for angular “play” or swivel for the cleat in the receptacle, typically on the order of ±15°. This feature provides a rotational traction cushioning effect wherein, depending on the movement of the shoe sole relative to the ground surface, traction may become effective gradually. 
     In the embodiments described above the cleat locking ridges and receptacle locking teeth are located outside the receptacle cavity, a feature which has many advantages. However, in some instances it may be desirable to provide these locking structures inside the receptacle cavity. Referring to  FIGS. 26 and 27 , a cleat  610  is provided with a stem  620  from the distal end of which two attachment flanges  623  project radially outward as in cleat  10 . Each attachment flange  623  has a series of side-by-side locking ridges  641  projecting upwardly from the top surface of the flange and extending radially outward from the stem. The upper end of the ridges is preferably linear but it can be curved or chamfered. The cleat hub is provided with two helical ramped segments  615  terminating in raised angular stops  616  surrounding stem  620 . Cleat  610  is similar to cleat  10  but, importantly, has no locking structures on its hub. 
     Receptacle  650  is adapted to receive cleat  610  in its cavity  655  contained in a boss  654 . The exposed surface of the boss end wall is provided with two ramped segments  660  to engage ramped segments  615  of the cleat in an angled interface as described for cleat  10  and receptacle  50 . The raised edge  661  at the terminus of each ramp cooperates with a respective angular stop  616  on the cleat to limit insertion rotation to the final angular orientation of the cleat. Boss  654  has no locking teeth; instead, locking teeth  670  are provided on the interior surface of the bottom wall of cavity  655  and are positioned to engage locking ridges  641  on flanges  623  when the flanges are rotated in the cavity to a locking position. The ridges  641  and teeth  670  engage in a washboard type of relation to prevent inadvertent rotation of the cleat from its final angular orientation. 
     It will be appreciated that the ridges and teeth shown in  FIGS. 26 ,  27  may alternatively, or in addition, be provided on the bottom surface of the attachment flanges  623  and undersurface of the distal end wall of boss  654 . The locking need not be limited to regular ridge and tooth structures but can be provided by irregular surface configurations on the inside surface of either end wall of the cavity and on either the top or bottom surfaces of the flange. As a further alternative surface irregularities such as bumps may be provided on the top surface of the cleat between the stem and locking structures an angular position to permit the irregularities to project into the cavity at the flange receiving opening in aperture  57  when the cleat is rotated to its final angular orientation. 
     The angled interface provided between ramped segments  15   a ,  15   b  on the cleat hub ramped segments  60   a ,  60   b  on the receptacle boss need not be limited to a flange-in-cavity type of attachment. Referring to  FIGS. 28 ,  30 A and  30 B, a cleat  710  is illustrated with a conventional threaded stem  720  projecting upwardly from the cleat hub  711 . Conventional traction elements extend downwardly from the cleat bottom. The top surface of the cleat is angularly subdivided into a plurality (in this case three) of shallow upwardly extending helical ramp segments  715   a ,  715   b ,  715   c  in angular sequence and disposed coaxially about the cleat axis A. The height of the ramp segments increases as a function of angular displacement about the cleat axis in the direction of cleat insertion rotation, and each ramp segment extends angularly approximately 120°. The raised terminal edges of the ramp segments  715   a ,  715   b ,  715   c , respectively, define radially extending shoulders or stops  716   a ,  716   b ,  716   c . These stops are positioned to abut corresponding rotational stop structure on the receptacle, described below, in the final angular insertion position of the cleat. 
     The downward facing surface of receptacle  750  is subdivided into three shallow depending helical ramp segments  760   a ,  760   b ,  760   c  disposed coaxially about the receptacle axis. The longitudinal height of ramp segments  760   a ,  760   b ,  760   c  increases as a function of angular displacement about the axis in the direction of cleat insertion rotation, and each ramp segment extends approximately 120° about the axis. The depending terminal edges of these ramp segments define respective radially extending shoulders or stops  761   a ,  761   b ,  761   c . Ramp segments  760   a ,  760   b ,  760   c  are positioned to be radially aligned with ramp segments  715   a ,  715   b ,  715   c , respectively, of cleat  710  in an angled interface during cleat insertion. In particular, upon rotational insertion of threaded stem  720  in threaded socket  755  the abutting ramp segments are forced into tighter axial engagement that increases with rotation angle until shoulder stops  716   a ,  716   b ,  716   c  abut respective shoulder stops  761   b ,  761   a    761   c . This occurs when the cleat has reached its final angular orientation relative to the receptacle and the frictional engagement between abutting ramp segments is at a maximum. 
     It is of interest to note that the ramp segments on the cleat may be inclined in the opposite angular direction with a different result. For example, in cleat  710  the ramped segments  715   a ,  715   b ,  715   c  increase in height in a counterclockwise direction. In cleat  810 , illustrated in  FIG. 29 , the ramped segments  815   a ,  815   b ,  815   c  increase in height in a clockwise direction. When cleat  810  is rotationally inserted into receptacle  750 , the ramped segments  815   a ,  815   b ,  815   c  of cleat  810  abut and ride along corresponding ramped segments  761   a ,  761   b ,  761   c  of the receptacle, with gradually tightening engagement, until the cleat ramp termini  816   a ,  816   b ,  816   c  move over the receptacle ramp termini  716   a ,  716   b ,  716   c  to permit the termini to snap longitudinally toward one another and then into angularly abutting relation to define the final angular orientation of the cleat sand receptacle. 
     The flange-bearing stem  20  need not be a single member. Specifically, as disclosed in U.S. Pat. No. 6,631,571 (McMullin), each attachment flange may be supported by its own stem which can be resiliently pivotally flexed slightly to permit small relative displacement between the supported flanges to assist during flange insertion into and removal from cavity  55  through aperture  57  and to more readily absorb laterally directed impact forces applied to the cleat without disengaging the locking structures. An example of such an arrangement is illustrated in  FIGS. 31 ,  32  wherein cleat  900  includes two stems  920   a ,  920   b  disposed in spaced relation on opposite sides of the cleat attachment axis. In the illustrated embodiment these stems are spaced 180° apart in symmetrical relation about the axis in order to be used with receptacle of  FIG. 6 . It should be appreciated that the stems can be asymmetrically positioned and that any number of stems may be provided, depending on the configuration of the receptacle with which it is used. The proximal ends of stems  920   a ,  920   b  are disposed at the top surface of the cleat hub. Respective attachment flanges  923   a ,  923   b  extend radially outward in 180° spaced relation from the distal ends of stems  920   a ,  920   b . These flanges, although possibly shorter in radial length than flanges  23   a ,  23   b  ( FIG. 1 ) because the spacing between the two stem, are positioned and configured to be received in the flange-receiving portions on aperture  57  ( FIG. 1 ) and function therein in the same manner as flanges  23   a ,  23   b . Two stop blocks  990   a ,  990   b , spaced by 180°, project upwardly from the cleat hub at angular locations spaced 90° from stems  920   a ,  920   b . The radial positions and lateral cross-sectional configurations of the stop blocks permit them to be aligned with and closely fit into respective flange-receiving portions of aperture  57  of receptacle  50  ( FIG. 1 ) in the final or locked angular orientation of the cleat and receptacle. As the cleat is rotated the sloped undersurfaces of the flanges become more tightly engaged with the sloped interior surface of the cavity end wall, and the distal ends of stop blocks  990   a ,  990   b  are pulled gradually closer to the distal end wall  56  of receptacle boss  54  ( FIG. 1 ) as the blocks are rotated along with stems the cleat. When the blocks reach the flange-receiving portions of aperture, which corresponds to the final or locking angular orientation of the cleat, the blocks are pulled up in a snap-like manner into respective aperture portions so that the blocks extend into the cavity. When so positioned the stop blocks serve to strongly resist inadvertent rotation and removal of the cleat from its locked position. In order to facilitate replacement of the cleat by a suitable wrench or tool as described above, the stop blocks may be constructed of resiliently flexible material to permit them to be bent sufficiently to become dislodged from aperture  57  in response to a sufficient torque applied to the cleat. Alternatively, or in addition, the side wall of the block facing the removal rotation direction may be sloped or otherwise contoured to permit removal from aperture  57  in response to the applied torque but as a result of normal use of the cleat. 
     Persons skilled in the art will understand that the use of two attachment stems is not a limiting feature of the invention and that three or more stems may be provided to be received in the receptacles of  FIGS. 19 and 21 , for example. Likewise, the number of stop blocks can be increased to accommodate a particular receptacle. It must also be noted that plural stem embodiments are not restricted to the use of stop block locking and that the locking structures described herein and illustrated in the various drawings can readily function with plural locking stems. 
     It will be appreciated that the embodiments described above and illustrated in the drawings represent only a few of the many ways of implementing the principles of the present invention. For example, the stem  20  and other attachment stems described herein need not be circular in lateral cross-section; any regular or irregular polygonal cross-section may be used. The attachment flanges  23   a ,  23   b  and the others described herein can have substantially any lateral peripheral shape as long as it is consistent with the functional features described herein. Likewise, boss  54  and cavity  55 , as well as the bosses and cavities in the various embodiments, need not have circular cylindrical configurations but instead can have any regular or irregular polygonal lateral cross-sectional shapes consistent with the operational principles described herein. 
     Surfaces and other structural features shown in the drawings with particular contours or topographies need not be so unless described as requiring same for a particular function. 
     As noted herein, although the invention has been disclosed with primary application for golf shoes, the principles are equally applicable for cleated shoes of other types used in other athletic activities, such as soccer, football, baseball, etc. 
     Having described preferred embodiments of new and improved methods and apparatus for interconnecting traction cleats and receptacles therefor, it is believed that other modifications, variations and changes will be suggested to those skilled in the art in view of the teachings set forth herein. It is therefore to be understood that all such variations, modifications and changes are believed to fall within the scope of the present invention as defined by the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.