Abstract:
Provided is a personal traction device that includes a traction mechanism that is very comfortable underfoot, while providing excellent traction over slippery surfaces as well as excellent long-term wear.

Description:
FIELD OF THE INVENTION 
     This invention pertains to personal traction devices that can be worn over footwear such as shoes or boots so that traction mechanisms extend over the sole of the shoe for increasing the traction of the sole. 
     BACKGROUND OF THE INVENTION 
     There are many versions of personal traction devices that can be mounted to shoes, boots, or the like, for increasing traction when walking on ice or snow-covered surfaces. 
     Such devices often include stretchable mounting straps that are configured to grasp the toe and heel portions of the boot. The traction mechanisms are connected to the straps and may be in the form of chains, flexible material with embedded metal studs, or other material with roughened or irregular surfaces that extend across the sole of the boot, usually in the vicinity of the sole that underlies the heel and metatarsal portion of the foot. 
     A number of factors must be considered when designing such traction devices. For example, some mechanisms that provide very good traction, such as outwardly projecting metal spikes, may suffer from rapid wear or be uncomfortable to walk on for a length of time, especially when one is in an environment where the walking surface may change between dry, hard surfaces and icy or snow-packed surfaces. Also, it is difficult to durably mount metallic members, such as spikes or studs, to a flexible cross strap or the like. To this end, some designs provide for replacing dislodged or worn spikes, which necessarily increases the cost and complexity of the device. 
     Some mechanisms that extend across the sole of the shoe or boot, such as relatively low-profile chains or coiled spring-like members may be more comfortable to the user, but they typically have less aggressive traction characteristics. 
     The present invention is directed to a personal traction device that provides a traction mechanism that is very comfortable underfoot, while providing excellent traction over slippery surfaces as well as excellent long-term wear. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a personal traction device in accord with the present invention shown mounted to a boot. 
         FIG. 2  is a plan view of a forward or toe assembly component of the personal traction device. 
         FIG. 3  is a plan view of a rear or heel assembly component of the personal traction device. 
         FIG. 4  is a perspective, enlarged view of one embodiment of a cleat component of the personal traction device. 
         FIG. 5  is an end view of the cleat of  FIG. 4 . 
         FIG. 6  shows a side view of a portion of a traction device. 
         FIG. 7  is a perspective, enlarged view of another embodiment of a cleat component of the personal traction device. 
         FIG. 8  is an end view of the cleat of  FIG. 7 . 
         FIG. 9  is a side view taken along lines  9 - 9  of  FIG. 8 . 
         FIG. 10  is a side view taken along lines  10 - 10  of  FIG. 8 . 
     
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
       FIG. 1  illustrates the traction device  20  mounted to a boot  22 . A generally ring-shaped elastomeric member  24  is stretched around the boot, above the sole of the boot. The elastic properties of that member  24 , as well as the friction between the member and the boot, secure that member in place. 
     The elastomeric member  24  is formed with several downwardly projecting tabs  26 . Each tab  26  is formed with an aperture for receiving a connector link  28  of a cable assembly  30 ,  32  that extends across the sole (underside) of the shoe as described more fully below. 
       FIG. 2  is a plan view of the forward or toe cable assembly  30  of the personal traction device. This assembly comprises a single length of stainless wire rope  34 , shown in dashed lines, and preferably having a 0.0625-inch (1.6 mm) diameter. The ends of the rope  34  are overlapped and fastened by a crimp  36 . 
     Crimps  38  are also applied in two places near the forward part of the rope to define two spaced-apart, forward connector loops  40  in the rope. Each of these loops is captured by one of the above mentioned connector links  28  that extend from each tab  26  of the elastomeric member  24 . 
     Similarly, crimps  42  are applied in two places near the rearward part of the rope to define two spaced-apart, reward connector loops  44  in the rope. Each of these loops is also captured by a connector link  28  that extends from a tab  26  of the elastomeric member  24 . 
     With continued reference to  FIG. 2 , the overall wire rope  34  can be considered as having four segments, each segment extending between a connector loop. For example, a transverse segment  46  of the assembly extends between the forward connector loops  40 . Another transverse segment  46  extends between the rearward connector loops  42 . A lengthwise segment  48  extends between a forward connector loop  40  and rearward loop  44  on each side of the assembly. 
     As seen in  FIG. 2 , the segments are arranged in a generally trapezoidal shape, with the two lengthwise segments extending along, but not parallel to, the long centerline  50  of the assembly (that centerline corresponding to the centerline of the boot to which the assembly is attached). The two transverse segments  46  extend generally across and perpendicular to that centerline  50 . 
     Each segment of the wire rope  34  is strung or threaded with cleats  52  and spacers  70  such that a spacer  70  is located between each cleat  52 .  FIGS. 4 and 5  respectively illustrate in enlarged perspective and end views the details of on embodiment of a cleat  52  made in accordance with the present invention. 
     In particular, each cleat  52  depicted in the embodiment of  FIGS. 4 and 5  is formed of durable metal, such as stainless steel, and is generally cross-shaped. The cleat includes a round through-passage  54  having a diameter (eg, 0.0781 inches or 2.0 mm) that is slightly larger than that of the wire rope that slides through the passage. Accordingly, the threaded cleat is free to rotate about the rope  34 . 
     The cross-shaped cleat  52  defines several edges where two surfaces meet. For example, as shown in  FIGS. 4 and 5 , a first edge  56  of the cleat is defined by the junction of the two surfaces shown at  58  and  60 . Another such edge  56 ′ is defined by the junction of the two other surfaces shown at  58 ′ and  60 .′ It is noteworthy that this pair of first edges  56 ,  56 ′ are parallel to one another and reside in a common plane, which is indicated by the “ground” line  62  in  FIG. 5 . 
     The cleat  52  is symmetrical about its center. Accordingly, a pair of second edges  64 ,  64 ′ matching but opposite to the first pair  56 ,  56 ′ are defined on the opposing side of the cleat. Those edges  64 ,  64 ′ are respectively defined by the junctions of surfaces  74 ,  76  and  74 ′,  76 ′ and likewise disposed in a common plane, which is shown by the “sole” line  66  in  FIG. 5 . Plane  66  is parallel to the opposing plane  62 . 
     The configuration of the first set of edges  56 ,  56 ′ as shown in  FIG. 5 , orients those edges to be pointing downwardly in the direction as shown by arrows “D” in  FIG. 5 . In this regard, a line that bifurcates the angle between the two surfaces that form the edge  56 ,  56 ′ is aligned with the direction that the edge is “pointing.” Thus, in  FIG. 5  the edges  56 ,  56 ′ are pointing in the downwardly direction “D,” normal to the plane  62 . 
     On the opposite side of the cleat  52 , the second set of edges  64 ,  64 ′ as shown in  FIG. 5  are oriented so that those edges are pointing upwardly as indicated by arrows “U” in  FIG. 5 , perpendicular to the plane  66  in which the edges are disposed. 
     Considering further the cleat shown in  FIG. 5 , the lower or ground plane  62  may be considered the surface (such as an ice-covered walkway) upon which the cleat  52  bears when fastened to the sole of a boot as shown in  FIG. 1 . The opposing plane  66 , in this instance, corresponds to the underside or sole of the boot  22 . 
     Consequently, all of the cleats of the device, when pressed between the sole  66  and ground surface  62  by the weight of the wearer, will have a downwardly pointing pair of sharp edges forced into the icy surface for providing excellent traction. In this regard, the configuration of the cleat (as described above) is such that when pressed between two planes ( FIG. 5 ) it will assume a stable equilibrium position. Specifically, the cleat rotates about the rope  24  by an amount sufficient to direct a pair of edges to rest upon or point to the lower surface, and an opposing pair of edges points to or engages the surface of the upper plane. 
     In one embodiment, the outermost radial surfaces of the cleat, such as surface  60 ′ is formed to be slightly arched or convexly curved, which curvature may enhance the tendency of the cleat to arrive at its stable equilibrium orientation just discussed. It is contemplated, however, that such surfaces could also be flat, and the cleat would still move to its stable equilibrium orientation ( FIG. 5 ) when pressed between two generally parallel planes. 
     As noted, the cleat is symmetrical so that the cleat shown in  FIG. 5  will assume a stable equilibrium orientation at any one of four different positions. That is, the cleat will assume a stable equilibrium orientation when rotated by any integer multiple of 90 degrees beyond what is shown in  FIG. 5 . Put another way, a third pair of edges  80 ,  80 ′ and opposing fourth pair of edges  82 ,  82 ′ are formed in the cleat  52  to function in the same manner as the above-discussed first and second edge pairs in instances where the cleat happens to be rotated 90 degrees from the orientation shown in  FIG. 5 . 
     It is noteworthy that the effect of the upwardly pointing edges of the cleat (edges  64  and  64 ′ in  FIG. 5 ), in addition to helping to stabilize the cleat in the position where the opposing edges point directly into the slippery surface  62 , is to provide cutting edges pointed toward the underside of the shoe. These edges tend to shear through ice, snow and other debris that may on occasion move between the cleat and the sole. In this regard, the upwardly pointing cleat edges provide a self-cleaning action for preventing unwanted buildup of material on the device. 
     Although the cleat shown in the figures has inner corners defining a 90-degree angle, it is contemplated that those corners could also be formed as concave curves, as shown by the dashed lines  88  in  FIG. 5 . 
     The opposing end faces  90  of the cleat are flat and reside in planes perpendicular to the long axis of the passage  54  in the cleat. It will be appreciated that where the end surfaces  90  join the edges (such as edges  56 ′ or  64 ′ shown in  FIG. 4 ) there is defined a relatively sharp point  92  in the cleat. Consequently, each end of the cleat has associated with it eight sharp points  92 . The wire rope upon which the cleats are carried is free to bend slightly to accommodate irregular surfaces, walking motions, etc. Consequently, the numerous sharp points  92  of the cleat will dig into the icy surface for enhancing traction, preventing sliding and otherwise supplement the traction provided by the edges discussed above. 
     The spacers  70  mentioned above (See  FIGS. 1 ,  2 , and  6 ) are hollow, cylindrical members, preferably made of stainless steel. As shown in  FIG. 6 , the outer diameter of the spacers is significantly less that the maximum cross sectional width of the cleats  52 . As a result, the numerous sharp points  92  of the cleats are exposed (for supplementing traction) by a degree much greater than would be the case if the cleats were threaded adjacent to one another with no such spacers. 
       FIG. 3  shows in plan view the rearward or heel cable assembly  32  of the personal traction device. This assembly comprises a single length of stainless wire rope  94 , having a 0.0625-inch (1.6 mm) diameter and shown in dashed lines. The ends of the rope  94  are fastened by a crimp  96 . This assembly includes alternating cleats  52  and spacers  70  configured and arranged as described above in connection with the toe cable assembly  30 . 
     Apex loops  98  are threaded onto the wire rope at each of three corners of the triangular-shaped heel assembly. Alternatively, crimps could be used instead of or in addition to these loops to define and stabilize the shape of the assembly. Each of the apex loops  98  is captured by a corresponding connector link  28  that extends from each tab  26  of the elastomeric member  24 . 
     With continued reference to  FIG. 3 , the overall wire rope  94  can be considered as having three segments, each segment extending between an apex loop  98 . For example, a transverse segment  100  of the assembly extends between the two forward apex loops. 
       FIGS. 7-10  illustrate another embodiment of a cleat component of the present invention. This cleat  152  is formed of durable material comprising, for example, stainless steel. The cleat  152  is generally cross-shaped and can be considered as having a central core portion  153 . The core  153  of the cleat has flat, opposing end faces  160  and has formed through it a round through-passage  154  having a diameter (e.g., 2.0 mm) that is slightly larger than that of the wire rope that slides through the passage. 
     The passage  154  (like the earlier described passage  54 ) includes a central axis as shown in the figures as line  155  for reference purposes. 
     Four spaced apart protrusions  157 ,  159 ,  161 ,  163  extend radially outwardly from the core  153  of the cleat  152 . These protrusions are evenly spaced apart from one another and are generally plate-like members, preferably having thicknesses ( FIG. 8 ) slightly greater than the diameter of the passage  154 . 
     In this embodiment, some of the protrusions are shaped to have sharp, bladed edges  165 . Bladed edges are, for the purposes of this description, edges formed from surfaces that meet at an angle of less than 90 degrees. In the present embodiment, the bladed edges are provided on two diametrically opposed protrusions  161 ,  163  (See  FIGS. 7 and 10 ). 
     Each bladed edge  165  is made up of the junction of two surfaces, one of which is a surface  167  that is formed so that it is inclined to be oblique (that is, neither parallel nor perpendicular) to the central axis  155  of the cleat. In this embodiment, that inclined surface  167  joins the extension of the end surface  160  of the cleat core ( FIG. 10 ), thereby defining a tapered portion in the protrusion  161 ,  163  that terminates in the bladed edge  165 . In a preferred embodiment, each protrusion  161 ,  163  has two inclined surfaces  167  and associated tapered portions, thus defining a bladed edge  165  on each of the opposite ends of the protrusion. 
     It is contemplated that a single inclined surface may be formed to extend along the length of the cleat and thus define a single bladed edge on one end of the cleat. Moreover, it is also contemplated that the cleat could be made with the end surface  160  of the cleat oriented to be inclined oblique to the central axis and thus serving as the inclined surface that imparts a taper into the protrusion and form a bladed edge. (For instance, in  FIG. 4 , the end face  90  of that cleat  52  may be formed obliquely to the central axis of the passage  54  and thereby defining at edge  60  a bladed edge as discussed in the present embodiment.) 
     It is noteworthy here that the bladed edges  165  described above are particularly useful for digging into ice-covered surfaces to improve traction. Moreover, all of the four protrusions may be formed with one or more such bladed edges. In the preferred embodiment, however, the other opposing pair of protrusions  157 ,  159  (See  FIGS. 7 and 9 ) are each shaped to define a wedge  169 . For the purposes of this description, a wedge is considered to be the shape resulting from the junction of two surfaces with an angle of 90 degrees or more between them. In the present embodiment (see, in particular,  FIG. 9 ), the wedge  169  is formed by two inclined surfaces that extend from opposing ends of the protrusion to join midway between those ends and define a sharp, outermost edge  171  of the wedge. 
     In view of the foregoing description of the embodiment of  FIGS. 7-10  it can be seen that the protrusions  157 ,  159 ,  161 ,  163  are arranged around the central axis  155  ( FIG. 7 ) in a manner such that each protrusions  161 ,  163  shaped to have opposing bladed edges  165  is adjacent to a protrusion  157 ,  159  that is shaped as a wedge with a central outermost edge  171 . One advantage to arranging the protrusions in this alternating manner is to maintain sufficient material in the cross section of the cleat (that is, along the axis  155 ) to increase durability of the cleat over what it might be if blade edges were formed on all four protrusions. 
     Moreover, in instances where, as in this embodiment, the protrusions are sized to extend radially outwardly by the same distance (see  FIG. 8 ), the adjacent blade edges  165  and wedge edge  171  provide three tripodal points (shown at  175  in  FIG. 7 ) that are disposed in a common plane and thus support the cleat  152  in a stable position upon a flat surface. 
     It will be appreciated that a similar tripodal arrangement of points  175  is provided on four sides of the cleat  152  (that is, at 90 degree intervals). As a result, the cleat  152 , when pressed between a shoe sole and ground surface by the weight of the wearer (those surfaces shown, for example at  62  and  66  in  FIG. 5 ), will provide a downwardly facing tripod of sharp points  175  forced into the icy surface for providing excellent traction, as well as an upwardly projecting tripod of sharp points  175  to engage the sole of the shoe. 
     The embodiments illustrated and described are not intended to be exhaustive or limit the invention to the precise form disclosed. The embodiments were chosen and described in order to explain the principles of the invention and its application and practical use, and thereby enable others skilled in the art to utilize the invention. Modifications, therefore, may be made to the preferred embodiments while still falling within the scope of the claims. 
     For example, each cable assembly could be modified to have more or fewer segments, or arranged in patterns other than the trapezoidal or triangular ones depicted here. Also, the tabs depending from the mounting strap may be equipped with rivets that capture one or more links for attachment to the loops on the wire rope. Such links may be bent or otherwise arranged so that the tab-to-wire rope connection rides smoothly over the boot. Moreover, it is also contemplated that many of the benefits of the configuration of the cleat  152  described above could be obtained if only three evenly spaced protrusions (rather than four) were employed.