Abstract:
A removably attachable traction gear for the underside of footwear having two primary components: a retaining member and a receptacle. These two components respectively replace the common screw and threaded receptacle systems found in for affixing traction gear to the underside of shoes. A partial turn of the traction gear securely locks the gear into the receptacle. The retaining member has a three-extension design so as to make the traction gear resistant to lateral forces applied to the ground-engaging end of the cleat. Locking is achieved through use of cantilevered fingers which press in during installation of the retaining member, and which spring back out to lock with mated indentations in the extensions. During installation a dome containing insole material is compressed. Unlocking is achieved through reverse turning the retaining member to force the springs back in, and removal is aided through re-expansion of the dome. In a preferred form, the invention is utilized to attach athletic cleats to a sport shoe.

Description:
The present application is a continuation of application Ser. No. 09/208,180, filed Dec. 9, 1998 now U.S. Pat. No. 6,108,944, which in turn is a continuation-in-part of application Ser. No. 09/062,037, filed Apr. 17, 1998, which in turn is a continuation-in-part of application Ser. No. 08/774,585, filed Dec. 23, 1996, which issued on Jun. 23, 1998 as U.S. Pat. No. 5,768,809, which in turn claims priority from provisional application Ser. No. 60/010,099, filed Jan. 17, 1996, and titled “Quick-Release Spike for Footwear.” These applications are incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to removably attachable mechanical connectors and the mounting of traction gear on the bottom of footwear, in particular, athletic footwear, using such connectors. 
     BACKGROUND ART 
     Conventional traction gear presently in use employ an attachment means consisting of screwing the traction gear into the mated receiving receptacle in the bottom of the footwear. Using this screw-type attachment method is especially laborious when one takes into account that a typical golf shoe, for instance, has eleven cleats; as a result, replacing the cleats on a pair of golf shoes entails unscrewing twenty-two cleats and screwing on twenty-two cleats, where each act of unscrewing or screwing entails several turns, typically two and one-half times, for each cleat. 
     An example of a typical prior-art cleat is in U.S. Pat. No. 4,723,366 (hereinafter the &#39;366 cleat), which patent is incorporated herein by reference. This patent describes a cleat which includes a metal stud infrastructure at the core of the cleat, the infrastructure having a vertical axis and two ends, a screw portion at a first end for engagement with a receptacle within a shoe, a ground end for tractive engagement with the ground, and a broad flange between the screw and head portions and extending radially outward from the vertical axis; a plastic skirt is molded directly upon the flange portion to form a unitary reinforced radial support member of the cleat. Installation of the &#39;366 cleat consists of screwing it into a mated receptacle in the bottom of athletic footwear. 
     Although some prior-art references show cleat-attachment systems that require less than a full turn, or they require a snap-on arrangement to lock the cleat in place, it appears none of these systems have found wide acceptance amongst users because of shortcomings in stability, ease-of-use, receptacle size and ease-of-manufacture. For instance, in U.S. Pat. No. 4,633,600 to Dassler, a cleat attachment system is disclosed in which a snap ring socket is utilized to affix a cleat to the bottom of a shoe. 
     In U.S. Pat. No. 3,267,593 to Turner, a cleat attachment system is disclosed wherein the top of the cleat spike has two extensions forming a rough T-shape out of the spike, where the spike is inserted into a mated receptacle having two grooves to receive the extensions. Upon complete insertion of the spike into a receptacle, the spike is turned until the extensions drop into receiving grooves at the top of the receptacle; a retaining ring is then slid onto the mid-section of the spike, this ring apparently preventing the spike from unseating the extensions from the grooves. 
     Similarly, in German Patent Application Nos. DE3134817A1 to Sportartikelfabrik Karl Uhl GmbH, and DE3423363A1 to Gebrüder Goldschmidt Baubeschläge GmbH, another T-spike design is disclosed in which internal to the mated receptacle are ramping means for engaging and retaining the spike extensions. In the former, a rough interior surface catches the extensions, while in the latter, a sloping interior engages the extensions. 
     U.S. Pat. No. 4,492,047 to Arff, discloses another T-shape spike in which the skirt is deformed during insertion. Insertion of the spike causes the extensions to go up a ramp and then down a ramp, pulling the spike into the receptacle, and leaving the extensions in a holding area. The skirt is deformed so as to result in a pressure against the socket, the pressure apparently holding the spike from accidentally traveling back up the ramp towards removal. 
     In U.S. Pat. No. 4,035,934 to Hrivnak, another T-shape spike is disclosed in which the spike column has two indentations. During installation, two spring arms, each positioned perpendicular to the surface of the shoe and parallel to the spike, are pressed in during insertion of the spike, and spring back out to press against the indentations upon complete insertion. Removal of this spike is achieved with a U-shaped tool which slides into the spike receptacle and pushes in the spring arms, thus freeing the spike for removal. 
     SUMMARY 
     A representative embodiment of the present invention includes a system 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The following drawings are intended to provide a better understanding of the present invention, but they are in no way intended to limit the scope of the invention. 
     FIG. 1 is a side view of a cleat according to one embodiment of the invention. 
     FIG. 2 is a top view of the cleat of FIG. 1, showing the shape of the lobes to be inserted into a mated receptacle in the bottom of athletic footwear. 
     FIG. 3 is another side view of the cleat of FIG.  1 . 
     FIG. 4 is a bottom view of the cleat of FIG.  1 . 
     FIG. 5 is a bottom view of a receptacle that may receive the FIG. 1 cleat. 
     FIG. 6 is a top section view of the FIG. 5 receptacle wherein the top layer of the receptacle has been removed. 
     FIG. 7 is a side vertical section of the receptacle of FIG.  6 . 
     FIG. 8 is a top view of the FIG. 6 receptacle wherein the top layer has not been removed. 
     FIG. 9A is a perspective right side view of a cleat according to a preferred embodiment of the invention. 
     FIG. 9B is a perspective top view of the FIG. 9A cleat. 
     FIG. 9C is a perspective front view of the FIG. 9A cleat. 
     FIG. 9D is a perspective left view of the FIG. 9A cleat. 
     FIG. 10 is a top view of the cleat of FIG. 9A, showing the shape of the lobes to be inserted into a mated receptacle in the bottom of athletic footwear. 
     FIG. 11 is another side view of the cleat of FIG.  9 A. 
     FIG. 12A is a top section view of a the receptacle for receiving the cleat of FIG. 9A, wherein the top layer of the receptacle has been removed. 
     FIG. 12B is a perspective bottom view of the FIG. 12A receptacle. 
     FIG. 13 is a side vertical section of the receptacle of FIG.  12 A. 
     FIG. 14 is a bottom view of a cover for the FIG. 12A receptacle. 
     FIG. 15 is a side view of FIG. 14 cover. 
     FIG. 16 is a partial view of a FIG. 9A cleat inserted into a FIG. 12A receptacle. 
     FIG. 17 is a bottom view of the FIG. 9A cleat. 
     FIG. 18 is a top view of an unassembled receptacle for receiving the FIG. 9A cleat. 
     FIG. 19 is a bottom view of the FIG. 18 receptacle. 
     FIG. 20 is a section view of the FIG. 18 receptacle. 
     FIG. 21 is a side view of a cleat according to a preferred embodiment of the invention. 
     FIG.22 is a side view of a cleat according to a preferred embodiment of the invention showing an alternative ground-engaging “soft” golf spike. 
     FIG. 23 is a top view of a cleat similar to FIG. 21 showing the top of the cleat connector. 
     FIG. 24 is a perspective top view of the cleat of FIG. 21 in a receptacle with the top cover removed. 
     FIG. 25 is a top view of a cleat connector of the type shown in FIG. 23, with the addition of semi-circular dust covers. 
     FIG. 26 is a perspective top view of the cleat connector of FIG.  25 . 
     FIG. 27 is a perspective bottom view of a preferred embodiment of a receptacle for receiving the cleat connector of FIG.  25 . 
     FIG. 28 is an inverted side view of a cleat using the cleat connector of FIG.  25 . 
     FIG. 29 is a perspective bottom view of an alternative receptacle having a center cone in the top cover. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     The invention comprises a system for allowing the quick attachment and release of a wide variety of traction gear. FIG. 1 shows that in one embodiment of the invention, the attachment system would be used to attach cleats, such as those disclosed in U.S. Pat. No. 4,723,366, to the underside of athletic footwear a cleat installed in the bottom of a shoe using the present invention, when viewed from the bottom, has a similar appearance to the preferred embodiment of the invention disclosed herein. Evident in FIG. 1 are the bottom side  17  and top side  16  of the plastic skirt  15 , the ground-engaging head portion  10  of the cleat, a base  13  to which the plastic skirt and ground-engaging portion are attached and a retaining member  20 , which in this case is a base  13  with three rounded extensions  22 , all of which are positioned around a central axis  28 . In a preferred embodiment of the invention, the top  16  of the skirt  15  is slightly concave, and the bottom  17  of the skirt  15  is somewhat convex. 
     FIG. 2 shows the topside  16  of the cleat skirt  15  and the retaining member  20 , which has a roughly triangular shape with indentations  26 . The extensions  22  of the retaining member  20  are used in conjunction with components inside the receptacle, shown as item  30  in FIG. 5, for locking in place a properly inserted retaining member  20 . Locking in place occurs after inserting the retaining member  20  into a mated receptacle opening  40  as shown in FIG.  5  and FIG. 6, and torquing the retaining member. The extensions  22  are attached to the base  13  (shown in FIG.  1 ), and together the extensions and the base form the retaining member  20 . In a preferred embodiment of the invention, a completed cleat, comprising the retaining member  20  and traction gear, is made out of plastic with a metal core used to reinforce the structure. Although the invention could be made entirely out of metal, it is preferable that the cleat be made partially of plastic and partially of metal. When the retaining member is plastic, the retaining member may be integrally formed with a plastic skirt of a golf cleat with a core, preferably metal, extending through the retaining member and the traction gear to form the ground-engaging head portion  10  shown in FIG.  1 . 
     In a preferred embodiment of the invention, upon insertion of the retaining member  20  into a receptacle, the angled surface  24  (shown in FIG. 1) of the extensions  22  allows for a tighter fit of the retaining member  20  into the receptacle  40  (shown in FIG.  5 ). The tight connection not only serves to give a stable connection between the shoe and traction gear, but also serves to keep moisture and debris out of the attachment system. 
     FIG. 3 is another view showing the structure and proportion of the retaining member  20  as attached to traction gear  21 . FIGS. 2 and 3 show that in a preferred embodiment of the invention, the extensions  22  form a broad retaining member  20 , and the base  13  is cylindrical and concentrically disposed around the center axis  28 ; the base  13  is attached to the extensions  22  and the traction gear  21 . 
     FIG. 4, a bottom view of the FIG. 1 cleat, shows that, in a preferred embodiment of the invention, cleats do not have to be redesigned beyond modifying the retaining member  20  (shown in FIG.  1 ), and that conventional cleat designs are intended to be used in conjunction with the new retaining member; once a cleat is installed, the change in the retaining system is not apparent. A standard golf-cleat wrench may be used to engage the traction gear through use of the wrench holes  18 . 
     FIG. 5 is a bottom view of a receptacle  30  that may receive the FIG. 1 cleat, showing the receptacle opening  40 , with indentations  44  along its perimeter for accepting the retaining member extensions  22  (shown in FIG.  1 ). FIG. 5 also shows the ledges  46  that while serving to form the shape of the opening  40 , also serve to hold the extensions  22  within the receptacle. Although preferred embodiments of the invention include a single receptacle opening  40 , alternate embodiments of the system could have a receptacle with separate openings for receiving extensions. 
     FIG. 6 is a section view of FIG. 5 where the top layer of the receptacle has been removed to show the inner-cavity structure for receiving the retaining member  20  (shown in FIG.  1 ). Within the cavity, formed by wall portion  50 , there are several cantilevered fingers  51 , or spring arms, that are designed to grip and hold an installed retaining member. When a retaining member is inserted into the indentations  44  and twisted, the twisting action causes a protruding edge of an extension  22  (shown in FIG. 1) to push into and bend the finger  51  to allow the extension to be turned past the location of the finger. Once the protruding edge of an extension passes the location of the finger, the finger springs back to nearly its original shape, so that surface  53  rests against the perimeter of the extension  22 . This allows the cleat to be removed, but only by exerting sufficient force to bend the finger  51  away from the surface of the extension  22 , an arrangement requiring much greater torque than that required during installation of the retaining member. In one embodiment, the fingers are elongated in shape, with surface  53  forming a curved tip to the finger. FIG. 6 also shows bumps  55  which serve as a means for preventing a retaining member from being turned too far. In a preferred embodiment, the cleat should not be turned more than about 60°. Coincident with the fingers  51  locking into place, the protruding edge of an extension is blocked from further movement by the bumps  55 , and the entire retaining system is prevented from falling out of the receptacle by ledges  46 . FIG. 6 also shows one method of attaching the receptacle to the underside of footwear by the use of mounting holes  57 . 
     Spacing within the receptacle may be designed such that during installation of a cleat, the cavity  40  in which the extension is turned gradually narrows to compress and securely hold the cleat in place. Preferably the spacing is consistent or more gradual than the angled surface, so that the angled surfaces  24  (shown in FIG. 1) of the extension  22  being pressed against the ledges  46  cause the fit to be tight. In addition, having three extensions parallel to the cleat skirt makes for a more secure base for a cleat. 
     FIG. 7 is a vertical section of a portion of the embodiment of the receptacle of FIG.  6 . This view shows the ledge  46  formed by the bottom layer  45  of the receptacle and the wall portion  50  that defines the cavity within the receptacle. This view also shows the slight rise  48  which forms a lip at the receptacle opening so that the edge of an installed cleat&#39;s skirt may overlay the lip. The lip helps hold the cleat in place and makes it more resistant to lateral forces while the cleat is in use. 
     FIG. 8, which is the FIG. 6 receptacle where the top layer has not been removed, is a view from the top of the receptacle  30  in accordance with a preferred embodiment of the invention. This view shows the top side  67  of the mounting holes for attaching the receptacle. 
     FIGS. 9A-9D,  10  and  11  show a preferred embodiment of a cleat having the same basic characteristics and structural concerns of the FIGS. 1,  2 , and  3  embodiments discussed hereinabove. Evident in FIG. 9A are the bottom side  17   b  and top side  16   b  of the plastic skirt  15   b , the ground-engaging head portion  10   b  of the cleat, a base  13   b  to which the plastic skirt and ground-engaging portion are attached and a retaining member  20   b , which in this case is a base  13   b  with three rounded extensions  22   b , the extensions having an angled surface  24   b  and being positioned around a central axis  28   b . FIGS. 9B-9D are respectively the perspective top, front, and left view of the FIG. 9A cleat. 
     Evident in FIG. 10 are the corresponding topside  16   b  of the cleat skirt  15   b  and the retaining member  20   b , with indentations  26   b . The extensions  22   b  of the retaining member  20   b  are used in conjunction with components inside the receptacle  84  of FIG. 12A, for locking in place a properly inserted retaining member  20   b . Locking in place occurs after inserting the retaining member  20   b  into a mated receptacle opening  40   b  shown in FIG. 12A, and torquing the retaining member. As with the FIG. 1 embodiment, upon inserting the retaining member  20   b  into a receptacle  84 , the angled surface  24   b  (shown in FIG. 9A) of the extensions  22   b  forces a gradual compression of the retaining member  20   b  as it is inserted into the receptacle cavity  40   b , resulting in a tight connection giving stability while also serving to keep moisture and debris out of the attachment system. 
     Also evident in the FIG. 10 embodiment is a modification to the FIG. 2 embodiment, where the extensions  22  of FIG. 2 are modified to include an indentation  70  that further enhances the invention&#39;s resistivity to unlocking and its unintentional removal through normal use. Increased resistivity is effected by an interlocking of a cantilevered finger  74  (shown in FIG. 16) with the indentation  70 . The cantilevered finger  74  corresponds to the cantilevered finger  51  of the FIG. 6 embodiment, in which the cantilevered finger  51  has been thickened to afford a greater resistivity to unintentional unlocking. Further, upon complete insertion of the retaining member  20   b  into an appropriate receptacle  84  (shown in FIG.  12 A), the end portion  90  of the cantilevered finger  74  rests within the indentation  70 . Consequently, removal of the cleat requires greater torque than that required to install the cleat. 
     FIG. 11 is another view showing the structure and proportion of the retaining member  20   b  as attached to traction gear  21   b , indicating the location of indentation  70 , as well as showing that the placement of the retaining member  20   b  and base  13   b  is concentrically disposed around the center axis  28   b.    
     FIG. 12A is a section view of a preferred embodiment of a receptacle for receiving the cleat of FIGS. 9A-9D,  10  and  11 , where the top layer of the receptacle  84  has been removed to show the inner-cavity structure for receiving the retaining member  20   b  (shown in FIG.  9 A). FIG. 12B shows a perspective view of the FIG. 12A receptacle. As with the FIG. 6 embodiment, included within the cavity, formed by wall portion  78 , are several cantilevered fingers  74  designed to grip and hold an installed retaining member  20   b . When a retaining member is inserted and twisted, the twisting action causes a protruding edge of an extension  22   b  to push into and bend the finger  74  to allow the extension to be turned past the location of the finger. Once the protruding edge of an extension passes the location of the finger  74 , the finger springs back to nearly its original shape, so that end portion  90  contacts the perimeter of the extension  22   b . As described hereinabove, when the end portion  90  contacts extension  22   b , there is an interlocking of cantilevered finger  74  with the indentation  70  (shown in FIG.  10 ). This allows the cleat to be removed, but only by exerting sufficient force to disengage and bend finger  74  away from indentation  70  and the surface of the extension  22   b , an arrangement requiring much greater torque than that required during installation of the retaining member. As with the FIG. 6 embodiment, the fingers are preferably elongated in shape, end portion  90  forms a curved tip to the finger, and bumps  55   b  serve as a means for preventing a retaining member from being turned too far during insertion. 
     Also evident in the FIG. 12A receptacle is another preferred embodiment for attaching the receptacle  84  to the underside of footwear by the use of a mounting slot  80 . In this embodiment, the perimeter  100  of the receptacle  84  comprises three flanges disposed around the receptacle opening  40   b . In preferred embodiments, within each flange  82  of the perimeter are two slots  80  for mounting the receptacle  84  to footwear. Mounting of the receptacle is by methods known in the prior art, and may include forming sole material around the slots, or inserting a pin or other object through the slot to effectively nail the receptacle to an inner-sole of a shoe, and then forming the outer-sole material around the receptacle so affixed. The slots  80  are separated by a pre-determined distance and are preferably curved to conform to the curvature of the flange  82  in which the slot  80  is set. Also shown are three openings  88  to allow for attaching a receptacle cover  96  (shown in FIG. 14) to the receptacle  84 . 
     FIG. 13 is a vertical section of a portion of the embodiment of the receptacle of FIG.  12 A. The FIG. 13 embodiment has a ridge  76  has been added in the bottom layer  86  of the wall portion  78  of the receptacle. In this preferred embodiment, the ridge  76  is located upon the downward side of the receptacle and helps assure mold seal-off. Sealing off the mold helps prevent sole material from the outsole molding process from accidentally spilling in over the bottom-end of the receptacle during production. (The receptacle and outsole are preferably molded ground-side up.) In addition, by adding ridge  76  to the basic design of FIG. 6, the structure of the FIG. 6 receptacle is strengthened, making it less susceptible to torques, distortions, or other forces. This results in better retention of the receptacle within the sole of athletic footwear. 
     FIG. 14 shows a receptacle cover  96  having three holes  92  corresponding to the three openings  88  shown in FIG.  12 . In preferred embodiments, the receptacle cover is designed to attach to and seal the top end of the receptacle  84  of FIG. 12A, so that during molding of a shoe sole around the receptacle, the sole material does not seep under the top edge of the receptacle and fill its cavity. In addition, at the center of the cover  96  is a dome  94 . This dome hangs downward from the top of the receptacle, into the receptacle cavity for receiving a retaining member  20   b  (shown in FIG.  9 A). 
     FIG. 15 shows a side view of the FIG. 14 cover, indicating the extent of the dome  94  with respect to the rest of the cover&#39;s  96  proportions. The dome forms a cavity  98  between a sole of a shoe and the top of the receptacle  84  (shown in FIG.  12 A). In preferred embodiments, during manufacture of a shoe sole, in addition to sole material being molded around the receptacles, sole material is also allowed to fill in the cavity  98 . Consequently, as a retaining member  20   b  (shown in FIG. 9A) is inserted into a proper receptacle, the insertion forces a compression of the dome which in turn compresses the sole material filling the dome. The dome  94  serves two purposes. First, when the retaining member  20   b  of traction gear is fully installed within a receptacle  84  (shown in FIG.  12 A), the compression of the dome results in a downward pressure upon the extensions  22   b  from the dome trying to re-expand into its original shape. Second, when one tries to remove the traction gear from the receptacle  84 , the re-expansion of the sole material helps push the retaining member away from the sole, thus aiding in the removal of attached gear. 
     In preferred embodiments, the extensions for the attachment system are molded using conventional molding processes. Preferably, the molding process uses mold components having expandable cavities, these cavities allowing for undercuts to be molded without the use of side actions or slides. The receptacle may be molded using conventional molding processes, where the receptacles are preferably produced on a horizontal or vertical press and, with the aid of precision mold design and building, are formed in a manner well-known in the art. 
     In preferred embodiments of the invention, during manufacture, the receptacle portion with the top cover attached is placed in an outsole mold, and the ground surface part of a shoe is then molded. The molding process is preferably one of injection or compression molding. The particular location of each receptacle within the mold depends on the intended use of the shoe and the design of the shoe&#39;s shape. During manufacture of the outsole of one embodiment of the invention, mold support-braces may be used to help ensure no deformation of the receptacles during the molding of the sole. Preferably, the support-braces are negatives of the receptacle&#39;s shape such that when a brace is inserted into a receptacle, the receptacle  84  and pin holes  88  (shown in FIG. 12A) are temporarily sealed off to prevent sole material from filling in the receptacle cavity  40   b  and pin holes  88 . These pins may also be used to help orient and position the receptacle so that sole material flows up to and not beyond the ridge  76  (shown in FIG. 13) that is visible on the ground side of the receptacle. Once the outsole is molded, a second material may be molded or cemented to the outsole, and also cemented to the upper portion of the shoe. In this embodiment, the outsole and second material combination form a completed sole having the embedded receptacles. 
     In some embodiments, the shoe sole may be formed of light-weight materials such as EVA or foam. In such embodiments, the sole material may be insufficiently strong to hold a receptacle firmly in place. Consequently, in preferred embodiments, a support plate may be added to the sole structure, wherein the receptacles are attached to the plate at the desired locations, and the sole is formed around the attached receptacles. Such plates may also be used for heel support for footwear having light-weight heels; similarly, for heel-plates, support-pins may also be used to help prevent heel receptacle deformation. 
     FIG. 16 is a partial view of a FIG. 9A cleat inserted into a FIG. 12A receptacle. Shown is a magnified view of the end portion  90  of a cantilevered finger  74  at rest in indentation  70  of retaining member  20   b . As described hereinabove, after installation of a cleat into a receptacle, the torque required to dislodge the cantilevered finger  74  from the indentation  70  is much greater than that required during installation. 
     FIG. 17, a bottom view of the FIG. 9A cleat, shows that in this embodiment of the invention, a three-pronged wrench is inserted into the three wrench holes  110  used to remove the cleat. Use of a three-wrench-hole design gives greater stability during insertion and removal of a cleat, and allows greater torque to be applied, without slipping out of the holes, during such insertion and removal. 
     FIG. 18 is a top view of an alternate embodiment where a modified FIG. 14 cover is attached to the FIG. 12A receptacle through a flexible attachment region  120 . In this embodiment, the receptacle  84  and cover  96  may be integrally formed of a single portion of production material, and simultaneously formed from a single mold. Before insertion of this embodiment of the receptacle into a shoe sole, the cover is flipped closed to cover the top of the receptacle. The FIG. 14 cover is modified to include two cover flanges  122  which, when the cover is closed, rest in-between two of the receptacle flanges  82 . The cover flanges  122  also have slots  124 , which in addition to the receptacle slots  80  described hereinabove, are used for mounting the FIG. 18 combined receptacle and cover to the underside of footwear. 
     FIG. 19 is a bottom view of the FIG. 18 embodiment, showing the ridge  76  (see FIG. 13 hereinabove) which helps prevent sole material from the outsole molding process from accidentally spilling in over the bottom-end of the receptacle opening  40   b  with attached FIG. 14 cover having the features as disclosed hereinabove for FIG.  12 A and FIG.  14 . 
     FIG. 20 is a top section view of FIG. 18, showing the relationship between the extent of the dome  94  and the receptacle  84 . Also shown is the region defined by portions  126 ,  128  for receiving the cover flange  122  when the cover is closed over the receptacle  84 . 
     FIG. 21 shows a side view of an alternative embodiment of a cleat having some of the same basic characteristics of the FIGS. 1,  2 , and  3  embodiments discussed hereinabove. Evident in FIG. 21 are a bottom  201  of a plastic skirt  203 , and a top  205  with receptacles  207  for a cleat wrench. The cleat also has a ground-engaging spike  209  and a base  211  to which the skirt  203  and the spike  209  are attached. FIG. 22 is a side view of another cleat with a cleat connector similar to FIG. 21 showing an alternative ground-engaging “soft” golf spike  225 . FIG. 23 is a top view of the cleat connector of the cleats in FIGS. 21 and 22 showing retaining member  213 , which in this case is the base  211  with three thermoplastic extensions  215  projecting radially outward in a direction perpendicular to a vertical axis  210  of the base  211  in FIG.  21 . Each extension  215  has a front side  217  approximately parallel to a radial midline  218  of the extension  215  and which extends from a radial end  220  of the extension  215  back towards the vertical axis  210  of the base  211 . Each extension  215  also has a back side  219 , roughly parallel to and substantially shorter than the front side  217 ; the back side  219  is also closer to the midline  218  of the extension  215  than the front side  217 . The back side  219  extends back from the radial end of the extension  220 , partway to the base  210  until it joins another surface  221  which is substantially perpendicular to the radial midline of the extension  218 , so as to form an L-shaped indentation  222 . In a preferred embodiment, the extensions  215  all lie in the same plane, and each extension  215  is equidistant from the adjacent extension. 
     FIG. 24 is a perspective top view of a preferred embodiment of a receptacle  251  for receiving the cleats of FIGS. 21,  22 , and  23  with the top cover removed to show the inner-cavity structure for receiving the retaining member,  213  in FIG.  23 . Within a cavity  253 , formed by wall portion  255 , are several protuberances  257  designed to grip and hold an installed retaining member  213 . When a retaining member  213  is inserted and twisted, the twisting action rotates the front side  217  of an extension  215  past a protuberance  257  so that the radial end  220  of the extension  215  compresses the protuberance  257 , allowing the extension  215  to turn past the protuberance  257 . The extension  215  can continue to rotate until the front side  217  of the extension  215  engages a stopping wall portion  259  of the cavity  253 . The receptacle  250  is designed so when the front side  217  of an extension  215  engages a stopping wall portion  259  of the cavity  253 , the protuberance  257  springs back to nearly its original shape and snugly engages the L-shaped indentation  222  on the back side  219  of the extension  215 . Each extension  215  of an installed cleat, therefore, is firmly held in place between a stopping wall  259  and a protuberance  257  so that the retaining member  213  is securely attached to the receptacle  250 . 
     Removal of the cleat requires rotation in the opposite direction from installation. In a preferred embodiment, the protuberances  257  and the radial ends  220  of the extensions  215  are shaped so that rotation of the cleat in the removing direction requires much greater torque than that required during installation. For example, the radial ends  220  of the extension  215  may be tapered on the front side,  223  in FIG. 23, so that the radial end more easily rides over and compresses the protuberance during installation. Without a taper on the back side  224  of the radial end of the extension  215 , substantially greater force is required for the radial end  220  to ride over and compress the protuberance  257  when rotation is in the removing direction. Alternatively, the protuberances  257 , rather than the extensions  215 , may be tapered to allow easier rotation in the installation direction and require greater force for rotation in the removing direction. 
     FIG. 25 is a top view of a cleat connector  260  of the type shown in FIG. 23, with the addition of semi-circular dust covers  261  between each extension  215 . Of course, the cleat connector  260  may be placed on top of a wide variety of surface engaging structures including both surface penetrating structures and non-surface penetrating structures. FIG. 26 is a perspective top view of the cleat connector  260  of FIG. 25, and FIG. 27 is a perspective top view of a preferred embodiment of a receptacle  262  for receiving the cleat connector  260  of FIG.  25 . To install the cleat, the connector extensions  215  are inserted into the receptacle&#39;s semicircular openings  263 . The cleat is rotated into place to engage the structure of the connector  260  with the internal structure of the receptacle  262  as described above with respect to FIGS. 23 and 24. This also rotates the dust covers  261  towards the receptacle openings  263 . As the connector  260  locks into place in the receptacle  262 , the dust covers  261  settle snugly into the receptacle openings  263  to seal the openings  263  so as to prevent the entry of debris from the ground into the receptacle  262 . 
     As shown in FIG. 28, the dust covers  261  may have an incline so that as the connector  260  rotates into place in the receptacle  262 , the leading edge  264  of the dust cover  261  is lower, or closer to the base of the connector  260  than is the trailing edge  265  of the dust cover  261 . As a result, as the cleat is rotated, the dust cover  261  initially rotates easily over the opening  263  of the receptacle  262 . Before the structure of the connector  260  locks into engagement with the internal structure of the receptacle  262 , the higher trailing edge  265  of the dust cover  261  becomes compressed by the edge of the opening  263  of the receptacle  262  increasing the amount of force required to rotate the cleat. Just as the structure of the connector  260  locks into engagement with the internal structure of the receptacle  262 , the trailing edge  265  of the dust cover  261  clears the edge of the opening  263  of the receptacle  262 . This releases the compression of the trailing edge  265  of the dust cover  261  which springs down into the opening  263  of the receptacle  262 . Thus, the vertical face of the trailing edge  265  of the dust cover  261  fits against the edge of the opening  263  of the receptacle  262  so as to form a secondary lock in addition to the primary lock of the structure of the connector  260  in engagement with the internal structure of the receptacle  262 . In addition to sealing against the entry of debris into the receptacle  262 , the secondary lock formed by the dust covers  261  in engagement with the opening  263  of the receptacle  262 , provides additional resistance against the undesired unlocking rotation of the installed cleat in high torque environments such as with baseball cleats. 
     FIG. 27 also shows a receptacle  262  with a receptacle cover  266  having a cover spring  267  which extends into a receptacle cavity defined by the receptacle openings  263 . The receptacle spring  267  performs two functions similar to that of the dome  94  in FIGS. 14 and 15. First, when a cleat connector  260  is installed so as to engage the structure of the receptacle  262 , the receptacle spring  267  is compressed and thereby exerts a downward pressure on the cleat connector  260  which increases the contacting force between the connector  260  and the receptacle  262 . Second, when the cleat is rotated for removal from the receptacle  262  (e.g., for replacement), the receptacle spring supplies an ejecting force on the cleat connector  260  which aids in disengaging the cleat connector  260  from the receptacle  262 . 
     These functions do not necessarily require the use of a dome  94  as in FIGS. 14 and 15, or a spring  267  as in FIG.  27 . FIG. 29 shows a receptacle cover  268  having a center cone  269 . The cone  269  performs the same functions as the previously discussed dome  94  and spring  267 . In addition, the size and strength of the cone  269  may be relatively substantial when the cleat connector  260  contains a similarly shaped mating depression  270 , shown in FIGS. 25 and 26. 
     It should be realized that while the various preferred embodiments of cleat receptacles differ in the complexity of their specific structures, this does not significantly restrict the materials which may be used to fabricate such receptacles. All or part of a receptacle may be fabricated from metal. Alternatively, all or part of receptacle may be fabricated from a synthetic material such as plastic or nylon. Metal offers great strength, but with relatively great weight. Synthetic materials may be relatively lighter, while somewhat less strong than metal. Either metal or synthetic materials may, however, be employed satisfactorily. 
     In the preceding description and following claims, the term “cleat” is consistently used, however, no distinction is intended to be created between cleats and spikes, nor should any be inferred. In addition, while preferred embodiments have been described in which a cleat may be removably attached to a shoe using the described connectors and receptacles, the use of such connectors and receptacles is not limited to attaching cleats to shoes, but may be generally employed as a removably attachable connector system in other applications which require the attachment of one mechanical structure to another. Similarly, it is of course apparent that the present invention is not limited to the detailed description set forth above. Various changes and modifications of this invention as described will be apparent to those skilled in the art without departing from the spirit and scope of this invention as defined in the following claims.