Abstract:
A set of horseshoes for race horses made of Zytel®211 nylon with an embedded metal toe grab, and having front horseshoes with a relieved toe portion on the bottom side contacting the ground, and having rear horseshoes with a gradually thickening toe portion on the top side contacting the hoof.

Description:
RELATED APPLICATIONS  
       [0001]     This application claims the benefit of U.S. Provisional Application No. 60/652,458, filed Feb. 15, 2005.  
         [0002]     This invention relates generally to improved non-metallic horseshoes, and more particularly to an improved set of front and rear horseshoes for racehorses. 
     
    
     BACKGROUND OF THE INVENTION  
       [0003]     Currently the horseshoe of choice for racehorses is made of aluminum in the conventional arcuate configuration corresponding to the shape of the horse&#39;s hoof and attached in the conventional manner with nails through spaced nail holes as is well known in the art. The aluminum horseshoes must be shaped to the proper size and configuration to fit the hoof. While aluminum horseshoes are light in weight, an aluminum horseshoe lasts only one month on racehorses before it has to be tightened. Also, aluminum transfers heat quickly and can aggravate the hoof causing a brittle hoof and cracked heel.  
         [0004]     For the above reasons, non-metallic, moldable plastic materials have been proposed for horseshoes. A number of prior art constructions and methods of attachment have been proposed, using synthetic resin materials. Metallic inserts have also been proposed, which are imbedded in the resin material and project to form “toe grabs”. Calks, defined as downwardly extending projections, also may be provided as embedded metal inserts, or molded as an integral part of the non-metallic horseshoe.  
         [0005]     A number of U.S. patents have disclosed horseshoes of synthetic resin material of more or less conventional shape, some of these having metallic toe grab inserts, the following list being exemplary.  
         [0006]     U.S. Pat. No. 3,050,133 issued Aug. 21, 1962 to Ketner discloses plastic horseshoes intended for racehorses having a metallic arcuate insert for a toe grab with tapered toe portions on the horseshoes for the forefeet, and a tapered calk on the bottom side of the horseshoes for the hind feet. Thermoplastic epoxy resins are the preferred materials.  
         [0007]     U.S. Pat. No. 3,283,825 issued Nov. 8, 1966 to Ward describes a metallic toe insert for a non-metallic horseshoe, and U.S. Pat. No. 3,310,115 issued Mar. 21, 1967, also to Ward, describes a non-metallic horseshoe and method of attachment to a horse&#39;s hoof. The Ward patents mention a number of possible materials including hard rubber, synthetic rubber, nylon, Teflon, and Mylar.  
         [0008]     U.S. Pat. No. 3,494, 422 issued Feb. 10, 1970 to Clark, describes a plastic horseshoe, stating that nylon is unsatisfactory and expressing preference for elastomeric polyurethane.  
         [0009]     U.S. Pat. No. 4,972,909 issued Nov. 7, 1990 to Rose describes a horseshoe of glass fiber filled thermoplastic polyurethane and contains a summary of other prior art non-metallic horseshoes.  
         [0010]     U.S. Pat. No. 4,993,494 issued Feb. 19, 1991 to Tuunanen discloses a non-metallic shoe with an internal ductile insert of a special plastic material.  
         [0011]     U.S. Pat. No. 5,048,614 issued Sep. 17, 1991 to Klimko, discloses another horseshoe of conventional shape, molded of cyanaprene urethane and containing metal inserts.  
         [0012]     In order for horseshoes to be most effective on racehorses, they should be flexible to allow the heel to spread, the material must be resistant to shock and impact, and a good insulator to heat. The configuration of the shoe must be designed differently for the forefeet and the hind feet, to account for the fact that when a horse is racing, the heel portions of the forefeet strike the ground first, whereas the toe portions of the hind feet strike the ground first.  
         [0013]     Accordingly, one object of the present invention is to provide improvements in non-metallic horseshoes as to the material used and the configurations for the front shoes and rear shoes.  
         [0014]     Another object of the invention is to provide an improved set of front and rear non-metallic horseshoes especially designed for improving the performance of racehorses.  
         [0015]     Still another object of the invention is to provide improved non-metallic front and rear horseshoes for racehorses which reduce the likelihood of injury to the feet of the horses.  
       SUMMARY OF THE INVENTION  
       [0016]     Briefly stated, the invention comprises an improved set of front and rear horseshoes of the type having an upper side for attachment to a horse&#39;s hoof and a lower side, each molded of non-metallic material in an arcuate configuration corresponding to the shape of a hoof and having a central toe portion, a pair of attachment portions each defining an recess in a lower side thereof with spaced nailing holes and terminating in a pair of heel portions, the central portion having an arcuate metal toe grab embedded therein and protruding from the lower side thereof. The improvement of the present invention comprises using Nylon 6 for the non-metallic material, relieving the heel portions of the front horseshoes on the lower side thereof to provide a gradually thinning cross-section toward the terminating ends of the heel portions, and thickening the heel portions of the rear horseshoes toward the upper side thereof to provide a gradually thickening cross-section toward the terminating ends of the heel portions. Preferably the Nylon 6 material comprises Zytel® 211 manufactured by E. I. DuPont deNemours &amp; Company, or equivalent formulation. 
     
    
     DRAWING  
       [0017]     The invention will be better understood by reference to the following description, taken in connection with the accompanying drawing, in which:  
         [0018]      FIG. 1  is a side elevational view of a racehorse&#39;s forefoot wearing the improved front horseshoe,  
         [0019]      FIG. 2  is an elevational view of a portion of the same racehorse&#39;s hind foot wearing the improved rear horseshoe,  
         [0020]      FIG. 3  is a plan view of the front horseshoe viewed from the lower or ground contacting side thereof,  
         [0021]      FIG. 4  is a side elevational view, partly in cross-section, taken along line IV-IV,  
         [0022]      FIG. 5  is a side elevational view in cross-section, taken along lines V-V,  
         [0023]      FIG. 6  is a plan view of the rear horseshoe, viewed from the lower or ground contacting side thereof,  
         [0024]      FIG. 7  is a side elevational view, partly in cross-section, taken along lines VII-VII, and  
         [0025]      FIG. 8  is a side elevational view in cross-section taken along lines VIII-VIII of  FIG. 6 . 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0026]     Referring now to  FIGS. 1 and 2  of the drawing, portions of a forefoot and a hind foot respectively of a racehorse are illustrated.  FIG. 10  shows a forefoot  10  shod with an improved front horseshoe  12  made according to the present invention, while  FIG. 2  illustrates a racehorse&#39;s hind foot  14  shod with an improved rear horseshoe  16  made according to the present invention. As indicated by the characteristic profile of the horseshoes, front shoe  12  includes a projecting metal toe grab  18 , and shoe  16  includes a similar metal toe grab  20 .  
         [0027]     In accordance with the present invention, the heel portions of the front horseshoes  2  are relieved, as indicated at  22  on the lower side to provide a gradually thinning cross-section. The heel portions of the rear horseshoe  16  are thickened on the upper side thereof, as indicated at  24 , to provide a gradually thickening cross-section toward the end. Rear horseshoe  16  is slightly shorter than front horseshoe  12  to accommodate the slightly more erect hind foot  14 .  
         [0028]     In accordance with the present invention, the material for the non-metallic horseshoes  12 ,  16  (other than the metal toe grabs  18 ,  20 ) is from the family of polyamides known as Nylon 6 or polycaprolactam. The preferred Nylon 6 formulation is Zytel® 211 manufactured by E. I. DuPont deNemours &amp; Company, or an equivalent formulation.  
         [0029]     The construction of the improved horseshoes is made clear by reference to  FIGS. 3 through 5  for the front horseshoe and  FIGS. 6 through 8  for the rear horseshoe.  
         [0030]     The front horseshoe  12 , shown in plan view in  FIG. 3 , has a conventional arcuate configuration corresponding to the shape of a hoof, with a central toe portion  26 , a pair of attachment portions  28 ,  30 , and a pair of heel portions  32 ,  34 . Front horseshoe  12  has an upper side  12   a  which attaches to the horse&#39;s hoof and a lower side  12   b  which contacts the ground. The upper side  12   a  is substantially flat throughout. The toe portion  26  includes an embedded metal toe grab  18 , which is formed in an arcuate shape conforming to the contour of the toe portion  26 . As seen in  FIG. 4 , toe grab  18  includes a flange  18   a  imbedded in the Nylon 6 material and a projecting portion  18   b.    
         [0031]     The attachment portions  28 ,  30 , define arcuate recesses  28   a ,  30   a , respectively, in lower side  12   b , and are provided with spaced nail holes  36  in the recesses.  FIG. 5  illustrates a cross-section taken through the attachment portion  28 .  
         [0032]     In accordance with the invention, the heel portions  32 ,  34  are relieved on the lower side as shown at  22  to provide a gradually thinning cross-section toward the terminating ends of the heel portions. The relief angle is on the order of 20° from the horizontal.  
         [0033]     Referring to  FIGS. 6 through 8  of the drawings, the rear horseshoe  16  includes a metallic toe grab  20  formed in an arcuate shape like the previously described toe grab. The rear horseshoe  16  includes a central portion  38 , a pair of attachment portions  40 ,  42 , and a pair of heel portions  44 ,  46 . Horseshoe  16  has an upper side  16   a  and a lower side  16   b . The upper side  16   a  is substantially flat over the central portion  38  and attachment portions  40 ,  42 .  
         [0034]     Reference to  FIG. 7  cross-section shows toe grab  20  has a flange  20   a  imbedded in the resin with a projecting portion  20   b . Attachment portions  40 ,  42 , include arcuate recesses  40   a ,  42   a , with spaced nail holes  48  in lower side  16   b .  FIG. 8  illustrates a cross-section through the attachment portion  40 .  
         [0035]     In accordance with the present invention, the heel portions  44 ,  46  are thickened toward the upper side  16   a , to provide a gradually thickening cross-section toward the terminating ends of the heel portions, as illustrated at  24 . The angle of increasing thickness is on the order of 10° from the horizontal  
         [0036]     The prior art mentions a number of non-metallic materials for horseshoes, such as hard rubber, synthetic rubber, nylon, Teflon, Mylar, polyurethane, cyanaprene urethane, and many others. While nylon is mentioned as a material, I have found that most nylons are, in fact, unacceptable materials for horseshoes for racehorses, because of the extreme conditions and other forces imposed on the shoes during a race. However, I have found that one class of nylon products, specifically Nylon 6, provides excellent results, due to its flexibility, resistance to impact and ease of casting or injection molding into the configuration of the horseshoes described above and illustrated in  FIGS. 1-8 . Particularly Zytel® 211, a formulation of Nylon 6 manufactured by E. I. DuPont deNemours and Company, has been found to provide superior results for the shoes illustrated.  
         [0037]     The preferred horseshoe, cast or injection molded from Nylon 6, preferably Zytel® 211, provides a flexible shoe which can be flexed to conform to the hoof and then attached with nails in the conventional manner. The Nylon 6 allows the imbedding of metallic inserts of various shapes and other imbedded metal calks if desired. The high impact resistance of Nylon 6 reduces possible cracking or breaking of the shoe during a race. As is known, when a horse is runing, the heel portion of the front hoof strikes the ground before the toe portion, whereas the toe portion of the rear hoof strikes the ground before the heel portion. To accommodate this, the heel portion of the front shoe  12  is relieved as shown at  22  to reduce the effect of impact when the heel of the forefoot first strikes the ground. As to the hind foot of the horse, contrary to the conventional projections from the lower side of the heel portions of the shoe, the heel portions are thickened toward the upper side as illustrated at  24 . This results in greater and more uniform support of the hind foot heel as it strikes the ground. Mud calks can also be added to project from the lower side of shoe  16  if desired.  
         [0038]     While there has been described what is considered to be the preferred embodiment of the invention, other modifications will occur to those skilled in the art, and it is desired to secure in the appended claims all such modifications as fall within the true spirit and scope of the invention.