referring now to the drawings , and in particular to fig1 thereof , what is shown in an all - surface sold 10 in place on footwear 11 . sole 10 may be permanently attached to shoe 11 or may be removable therefrom and placed , either with another , similar sole after excessive wear , or with another sole that has different characteristics . as generally shown , sole 10 has a bottom , work - contacting surface 12 , from which protrude a plurality of metal studs 13 . the upper surface 14 of the sole is not seen in fig1 but lies in juxtaposition to the upper of the shoe 11 . the pattern in which the studs 13 are arranged is predetermined and is not considered to be part of the present invention . the structure of a stud 13 , which is preferably made of metal , is best seen in fig2 and 3 . as is the case with the studs of my u . s . pat . no . 5 , 634 , 283 , each stud 13 is formed with an anchoring portion 15 , a tip portio 16 , and a cylindrical or conical shank or shaft portion 17 so that it will remain substantially in place in relation to the resilient material of the sole in which it is encased . the tip 16 may be of a variety of shapes so long as its function of engaging a surface on which the wearer of the footwear 11 places it is maintained . thus , the tip portion 16 is shown as cylindrical , but may also be conical with the apex of the cone projecting outwardly from the bottom surface 12 of the sole 10 . the shaft 17 serves the function of connecting the tip and anchor of a stud . indeed , the tip portion may simply be constituted as the extremity of the shaft 18 . what is important to certain embodiments of my resilient , all - surface sole is the nature of the composition of the sole 10 . in my patent it is disclosed , but not limited to being uniform and made from a resilient material , e . g ., natural or synthetic rubber . in the embodiment of fig2 the material from which the sole is formed is of the same general , resilient nature , but the sole is not uniform in substance or resiliency . the rubber body of the sole is harder , that is , of less resilience , at a location adjoining the bottom , work contacting surface 12 of the sole 10 . more dense , less resilient zones of the sole are indicated by reference number 20 and adjoin bottom surface 12 . less dense portions are indicated by reference number 21 and adjoin upper sole surface 14 . portions of intermediate density lie between the zones 20 and 21 , and are indicated by reference numeral 22 . as a consequence , in that illustrated embodiment the density and resilience of the sole 10 decreases from the sole bottom surface 12 to the sole upper surface 14 , and in this embodiment it is preferred that such decrease be uniform in its extent , that is , that the resilience of the sole uniformly increase as one moves from the bottom surface 12 to the upper surface 14 of the sole 10 . in the fig2 embodiment it will also been seen that the anchoring portion 16 of the stud 13 is embedded in the rubber sole approximately halfway between the bottom and top sole surfaces . in this position the anchor 15 is located at a part of the thickness of the sole that is of lesser density and greater resilience than that portion 20 adjoining bottom surface 12 . in this structure the stud 13 will be able to be retracted more easily when the user of the footwear 22 steps on a hard surface than if the resilience of the sole were uniform throughout its depth . yet the hardness of the rubber at the bottom surface of the sole will still be of greater density , and therefore provide greater wear resistance and sturdiness to the footwear . however , retraction of the stud will still be adequate if the wearer of the shoe is of light weight , for example . the illustration of fig3 shows a different , preferred embodiment . here harder rubber layers are disposed adjoining both surfaces of the sole 10 . thus , a relatively hard layer 25 is located at the bottom surface 12 of the sole and , similarly , hard layer 26 is located at the upper surface 14 of the sole . however , those relatively hard layers have between them a softer , more resilient layer or zone 27 , which in effect is sandwiched between the more dense layers . the reason for the layering of more and less resilient zones in the fig3 embodiment is to enable the stud 13 to be retracted more easily into the sole 10 , while still maintaining a relatively firm sole bottom surface that will resist undue wear . thus , in this embodiment of my invention the shaft 17 of stud 13 extends through the less resilient portion 27 and into the more resilient portion 27 , in which the anchor 15 of stud 13 is located . in this manner the stud is more readily retractable because it anchor portion 15 is encased within the more resilient zone 17 . still , the less resilient outer layer 25 adjoining the bottom surface 12 of the sole 10 is in contact with the work , i . e ., the surface on which the wearer is striding . in this manner ease of retractability of the stud or spike is enhanced while the wear resistance of the footwear is the same as if the denser bottom layer of the sole extended throughout the entirety of the sole . still another embodiment of my invention is illustrated in fig4 of the drawings . here the sole 30 is formed of a single zone of rubber , and a cleat portion 31 extends downwardly and forms , in part , the bottom surface of the sole . encased within the body of the sole is a stud 32 , comprised of an anchor 33 and a tip 34 joined by a shaft 35 that extends substantially perpendicular to the horizontal axis of the sole 30 . what is believed to be unique vis - a - vis my prior patent , however , is the groove 37 that surrounds the tip and forms an annular opening about the tip 34 and in this case a lower portion of the shaft 35 . as the shaft of the stud 32 is usually formed from metal , providing such an annular recess 37 enables some flexing of the stud when it contacts a hard surface , and such flexing permits unwanted scarification of that surface in addition to the resilience imparted by the stud anchor 33 embedded in the resilient sole 30 . [ 0027 ] fig5 shows another preferring embodiment of my invention that is similar to that of fig4 . the difference here is that the sole 40 is formed from two layers of rubber , an upper or inner layer 41 and an outer , work contacting zone or layer 42 . a stud 43 is provided , which stud includes an anchor 44 joined by a shaft 45 to a stud tip 46 . here , too , the tip 46 is surrounded by annular recess 47 to permit some flexing of the tip and associated shank 45 . in the fig5 embodiment outer layer or zone 42 is of harder , more wear resistance material , while inner layer 41 is more resilient . so , as the anchoring portion 44 of stud 43 is backed by more resilient zone 41 , the stud can be retracted far more easily than if it had to press against the harder , less resilient zone 42 . finally , the embodiment illustrated in fig6 employs another combination of hard or more resilient layers of rubber . in this embodiment sole 50 is formed from a relatively hard upper layer 51 of rubber or other material , to which is adhered a relatively resilient layer 52 . then a cleat 53 formed of relatively hard rubber protrudes downwardly from the resilient layer 52 . the stud 54 extends with its tip 55 in hard layer 53 and shaft 56 passing through that hard layer into zone 52 in which its anchor 57 is encompassed . in this structure the stud 54 can be retracted with a fair degree of ease , as its anchor need only compress a part of the more resilient layer 52 while both the work contacting cleat 53 and the upper layer 51 of the sole 50 are formed from a less resilient material adapted to provide great wear resistance and rigidity to the sole in its entirety . in this embodiment as well , the annular recess 57 permits some flexibility of the tip and tip 55 and shaft 56 of the stud 54 . with regard to the manufacture of the soles disclosed herein , they can be made by molding in one piece or , where the sole is formed from layers of materials of difference degrees of resilience , by separately forming each layer and then fusing the layers together . the hardness of the synthetic or natural rubber compounds utilized will vary as set forth in u . s . pat . no . 5 , 634 , 283 , from between about 65 to 90 durometer shor a . where greater hardness and less resilience are desired , the sole hardness will be at a maximum , whereas where much more resilience is desired , the shor durometer hardness will be at a minimum . nevertheless , such variation in hardness are doubtless within the skill of those in this art , and i do not wish to be limited as to any specific hardness or resilience employed , other than as such hardness or resilience in one part of the sole may be contrasted with those factors in another layer of the sole . it will be apparent to those of skill in this art that certain modifications and alterations to the preferred embodiments of my invention described and illustrated herein will be found obvious without departing from the spirit of the invention . exemplarily , the provision or deletion of a cleat from the bottom surface of the sole is an obvious expedient . it is desired , therefore , that all such alterations and modifications be included within the purview of the invention , which is to be limited only by the scope , including equivalents , of the following , appended claims .
a resilient shoe sole having a less resilient outer layer and a more resilient inner layer , and retractable studs anchored in the inner , more resilient layer . the bottom surface of the sole has annular grooves formed around the tip portions of the studs to permit those portions to flex when pressure is applied to the bottom surface , as during walking on a hard surface .