Abstract:
A running or jogging shoe having an improved outer sole equipped with replaceable synthetic insert elements having a uniquely contoured shape adapted to be threadedly secured in overlapping relationship to raised projections on the sole exterior. In a first embodiment, the insert elements are adapted to receive and retain conventional spikes. In a second embodiment, the insert elements include integrally formed gripping projections. By replacing worn insert elements, the useful life of the outer sole, and thus the shoe as well, can be extended significantly.

Description:
BACKGROUND OF THE INVENTION 
     The present invention pertains generally to athletic shoes and more particularly to the spiked sole construction of a track shoe of the type employed for running and jogging activities. 
     It has been a practice in the prior art to provide the soles of track shoes with relatively large threaded cavities for inserting replaceable steel or synthetic spikes. Those skilled in the art will appreciate that detachable threaded spikes permit the useful life of the track shoe to be extended since the spikes themselves tend to wear out much faster than the sole and other parts of the track shoe. 
     It is a primary object of the present invention to provide an improved sole for an athletic shoe adapted to receive replaceable spikes to permit the useful life of the sole and shoe to be extended. 
     A particular object of the invention is to provide a sole for an athletic shoe which is equipped with replaceable synthetic elements adapted to carry steel or synthetic spikes or spike-like gripping projections while projecting the sole from excessive wear in the vicinity of the spikes or gripping projections. 
     In addition to extending the useful life of athletic shoes, the replaceable synthetic elements of the present invention have the advantage of reducing the weight of the shoe in comparison with shoes employing conventional steel spikes. 
     Other objects and advantages of the invention will become apparent upon consideration of illustrative embodiments thereof described in conjunction with the accompanying drawings. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, a sole for athletic shoes is provided with a plurality of raised projections each of which has a central cavity of a relatively large diameter with threaded interior walls for receiving a replaceable protective insert element having a specially contoured structure. Each replaceable insert element includes an outer wall which overlaps the portions of the respective raised projection, thereby protecting the raised projections from the wear and tear of use in order to extend the useful life of the sole. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic plan view of the outer surfaces of a sole for a track shoe illustrating by way of example two embodiments of replaceable protective insert elements, each being disposed at a selected one of several possible locations on the sole. 
     FIG. 2 is a greatly enlarged fragmentary view of a replaceable protective insert element in accordance with a first embodiment of the invention taken in vertical cross section along line 2--2 of FIG. 1. 
     FIG. 3 is a greatly enlarged fragmentary view of a replaceable protective insert element in accordance with a second embodiment of the invention taken in vertical cross section along line 3--3 of FIG. 1. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to FIG. 1, a sole for use on a track shoe or the like is illustrated and designated generally by reference numeral 10. The sole 10 comprises a sole plate 12 of a moldable polymeric material, suitable examples of which include polymide, polyacetale, polyurethane, polyvinyl chloride, and rubber. The sole plate 12 can be secured to a track shoe (not shown) in accordance with conventional manufacturing techniques. The sole plate 12 has a major exterior surface 14 on which a plurality of generally conial-shaped, raised areas or projections 16 are disposed in a pattern as illustrated by way of example in FIG. 1. 
     FIGS. 2 and 3 illustrate first and second embodiments of replaceable protective insert elements, respectively designated by reference numerals 18a and 18b, each having a uniquely contoured shape, the details and principal purposes of which will be described below. The replaceable insert elements 18a and 18b preferably are fabricated from the same moldable polymeric material used to fabricate the sole plate 12. 
     The features of the preferred sole plate 12 and the various common features of the insert elements 18a and 18b will presently be described with reference to FIGS. 2 and 3, wherein similar parts are designated using the same reference numerals and wherein reference numeral 18 will be used in the generic sense to both elements 18a and 18b. 
     The projections 16 are preferably integrally formed portions of the molded sole plate 12. Each projection 16 includes an exterior surface 20 rising from the major exterior surface 14 of the sole plate 12 to an annular rim 22 at an elevation above the major surface 14. It will be understood that terms such as &#34;above&#34; and similar directional terms used in this specification and the appended claims are intended to be construed from the relative point of view of FIGS. 2 and 3. Extending entirely under each projection 16 is a circular base portion 24 of the sole plate 12. Each projection 16 includes an interior wall 26 having sawtooth-shaped threads defining an annular cavity above the base portion 24 and within the annular rim 22. 
     Each insert element 18 includes an annular wall 28 having outwardly facing sawtooth-shaped threads constructed to mate with the threaded wall 26 to permit insert elements 18 to be installed in the cavities of the projections 16. Each insert element 18 includes an outer wall 30 extending from its respective threaded annular wall 28 to overlap adjacent annular rim 22 and tightly conform to the raised exterior surface 20 of the projection 16 within which the insert element 18 is secured. 
     Now referring to FIG. 2, the features unique alone to the first insert element embodiment 18a will be described. A metal socket 32 having a threaded opening 34 is anchored within the insert element 18a. The socket 32 preferably includes at least one anchor member 36 extending radially outward into the insert element 18a to firmly secure the metal socket 32 therein. It will be appreciated that the metal socket 32 can be firmly secured within the insert element 18a as depicted in FIG. 2 in accordance with conventional insert-molding techniques. The metal socket 32 thus provides an excellent means for securing a replaceable metal spike (not shown) to the sole plate 12 by merely screwing the spike into the threaded opening 34. It will also be appreciated that a specially adapted tool (not shown) can be used to screw the insert element 18a into the threaded interior wall 26 or that the replaceable metal spike itself can be used for such purpose. 
     Now referring to FIG. 3 in conjunction with FIG. 1, the features unique alone to the second insert element embodiment 18b will be described. The insert element 18b includes two circular patterns of integrally molded gripping projections consisting of an outer pattern of gripping projections 40 disposed above a peripheral portion 42 of the outer wall 30 and an inner pattern of gripping projections 44 disposed above the threaded annular wall 28. The gripping projections 40 and 44 are spike-like in appearance and are preferably generally cylindrical in shape as clearly depicted in FIG. 3. It will be appreciated that each outer gripping projection 40 is vertically supported by the portion of the major exterior surface 14 of the sole plate 12 which underlies the peripheral wall portion 42 of the element 18b. In order to effect installation or removal of the insert element 18b from the cavity of its respective projection 16, a cross-shaped recess 46 is provided at the center of the element 18b as seen best in FIG. 1, thereby enabling the element 18b to be screwed into or out of the threaded interior wall 26 using a suitable tool (not shown) such as a phillips screwdriver. 
     From the foregoing description of the two illustrative embodiments of the replaceable protective insert elements 18, those skilled in the art will appreciate the many advantages afforded by the present invention. For example, it will be readily apparent that the use of a synthetic material for all or most of each insert element 18 in conjunction with the relatively thin contoured shape of each such element 18 provides a sole construction which is extremely light in weight and has a maximized useful life while also exhibiting optimum versatility and performance characteristics. Of particular importance is the overlapping effect of the outer wall 30 of each element 18 in protecting the respective raised projection 16 against the severe wear and tear of use. The protective insert elements 18 can be replaced economically when worn out whereas the raised projections 16 comprise permanent irreplaceable parts of the sole plate 12. 
     A further significant advantage of the present invention, which can be appreciated from FIG. 1, is that insert elements 18 of different constructions can be employed simultaneously in various patterns in accordance with the desires of the user athlete. For example, the athlete may choose to employ the insert elements 18a of FIG. 2 without spikes at certain selected locations and the insert elements 18b of FIG. 3 at the remaining locations of the raised projections 16 in order to adapt the sole 12 of the shoe to track conditions, the type of athletic event, or numerous other variables. Accordingly, in such an example, there will be elements 18a at some locations extending to one elevation beyond the major surface 14 and elements 18b at other locations extending to another elevation beyond the major surface 14. Furthermore, different types of elements 18 of varying hardness can be employed at different selected locations in accordance with the desires of the athlete, which can be advantageous in reducing the incidence of tendonitis and other running-related injuries. 
     Although only two embodiments of replaceable insert elements 18 have been specifically illustrated and described in detail, it will be appreciated that many adaptations, modifications and alternatives are contemplated by the present invention. For example, the present invention contemplates the alternative embodiment of a replaceable insert element without a provision for spikes or spike-like gripping projections, such as would be provided by the embodiment of FIG. 3 wherein the gripping projections 40 and 44 are removed. Such a spike-free embodiment might be especially desirable for use on a synthetic track to provide optimum traction and yet having the advantages of replaceability and extended sole life. As a further example, the present invention contemplates an alternative embodiment wherein metal spikes are permanently molded into replaceable synthetic elements, such as would be provided by the embodiment of FIG. 2 modified by replacing the metal socket 32 with a threaded metal spike. Having the benefit of the presently disclosed invention, numerous other alternative embodiments which are within the spirit and scope of the appended claims will be suggested to those skilled in the art.