HORSESHOE IMPACT PAD AND METHOD

FIELD OF THE INVENTION

[0001] The present invention is directed to an improved horseshoe for dampening the shock of impact when a hoof strikes the ground, and in particular, it is directed to an impact absorbing composite impact pad inserted between the horseshoe and hoof. The composite impact pad includes a retainer member that is adhesive bonded to the horseshoe and fixed to the hoof, and a cushion member that is adhesive bonded to the horseshoe and coupled to the retainer member. The cushion member spans the toe area, quarter, and heel areas of the horseshoe, and it has lower shore hardness than the material used to make the retainer member. The softer cushion member supports and reduces pressure on the sole of the hoof when the sole flexes downward in response to each impact of the hoof on the ground, thereby eliminating a major cause of hoof lameness.

[0002] When a horse runs at 30 miles per hour, about 48.3 kilometers per hour, the concussive force generated on each hoof as it strikes the ground is about 2,600 psi (182.8 kg/cm ² ). In the past, various impact pad devices of different sizes, shapes, and materials have been inserted between the hoof and horseshoe to protect the hoof from the shock of impact (concussive force) when the hoof strikes the ground. Such impact pad devices of the past are manufactured from resilient materials such as rubber, leather, felt, plastic, and the like, and they are either nailed, bonded, or nailed and bonded to the hoof and shoe.

[0003] These earlier impact pads are effective in that they are able to cushion the shock of impact. However, each time the hoof strikes the ground, the force of the impact causes the resilient impact pad to distort or flex along the direction of the applied force. In other words, the impact pad distorts with each hoof beat. Such repeated distortion in the impact pad causes lateral and/or transverse movement between the horseshoe and hoof, and it generates shear along the connection that fastens the horseshoe to the hoof wall. For example, in a mechanical connection, where the horseshoe and impact pad are fastened to the hoof wall with nails, the repeated shoe movement tends to bend the nail shank, and over time, the nail will shear off leaving part of the nail in the hoof wall. As more nails shear, the shoe will shift and cause damage to the hoof wall, and sections of the hoof wall are torn away when the shoe is ripped off by the force of impact. In a chemical connection, where the impact pad is bonded to the horseshoe and to the hoof

wall with an adhesive, the horseshoe may be ripped from the hoof without any prior warning such as the shoe misalignment associated with mechanical connections. In addition, the glued connections of the past do not allow the heel area to expand and move as needed.

[0004] Accordingly, there is a long felt need within the art to provide a impact pad that includes a soft component that dampens the force of impact, eliminates pad distortion, allows the heel to move freely, and reduces pressure when the sole of the hoof flexes on impact; in combination with a hard component that provides a stable connection and minimizes shear effect on the nails.

SUMMARY OF THE INVENTION

[0005] Accordingly, it is a first object of the present invention to provide a composite impact pad that cushions the shock of impact and minimizes shear when the hoof strikes the ground.

[0006] It is another object of the present invention to provide a composite impact pad that minimizes shoe movement and thereby provides improved stability when the horse pushes off from the toe area of the composite impact pad.

[0007] It is a further object of the present invention to provide a composite impact pad with a retainer member that is fastened to a hoof and shaped to couple to and clasp the cushion member so that the clasped cushion member maintains dimensional stability when the hoof strikes the ground

[0008] It is another object of the present invention to provide a composite impact pad wherein retainer member is adapted to transfer concussive forces into the coupled and clasped cushion member.

[0009] It is still another object of the present invention to provide a composite impact pad where the cushion member has lower shore hardness on a durometer scale than the shore hardness of the retainer member fastened to the hoof.

[0011] It is yet another object of the present invention to provide a composite impact pad that includes a retainer member fastened to a hoof and coupled to the cushion member with a half-lap joint.

[0012] In satisfaction of the foregoing objects and advantages, the present invention includes a horseshoe in combination with a composite impact pad whereby the horseshoe comprises a lateral side, a medial side, a bottom surface, and a top surface that is defined by a toe area, a first quarter area and a second quarter area along

opposite sides of the top surface, and a first heel area and a second heel area along said opposite sides of the top surface, and whereby the composite impact pad includes a retainer member and a cushion member, the retainer member adhesive bonded to the top surface of the horseshoe, adapted for attachment to a hoof, and shaped to receive and capture the cushion member within a coupling provided therein, the cushion member is adhesive bonded to the top surface of the horseshoe, adhesive bonded within the retainer member coupling, and shaped to span the toe, quarter and heel areas of the horseshoe.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a schematic view showing the plantar surface of a horse hoof.

[0014] Figure 2 is a cross-section view showing a prior art impact pad fastened to a hoof. [0015] Figure 3 is a cross-section view similar to Figure 2 showing the prior art impact pad striking the ground. [0016] Figure 4 is an isometric view of the preferred embodiment of the present invention with one-half of the composite impact pad removed. [0017] Figure 5 is a plan view showing the retainer member of the preferred embodiment. [0018] Figure 6 is a plan view showing the cushion member of the preferred embodiment. [0019] Figure 7 is a plan view of the preferred embodiment of the present invention with one-half of the composite impact pad removed. [0020] Figure 8 is a plan view showing the entire retainer member and coupled cushion member. [0021] Figure 9 is a cross-section view showing the impact pad of the present invention fastened to a hoof. [0022] Figure 10 is a cross-section view similar to Figure 9 showing the impact pad of the present invention striking the ground. [0023] Figure 11 is a view similar to Figure 1 showing the preferred embodiment of the present invention fastened a horse hoof. [0024] Figure 12 is a view similar to Figure 11 showing an alternate embodiment of the present invention fastened to a horse hoof. [0025] Figure 13A is a partial isometric view showing an alternate embodiment where the retainer member is integral with the horseshoe.

[0026] Figure 13B is a partial isometric view showing a cushion member coupled to the horseshoe of Figure 13A. [0027] Figure 14 is a partial isometric view showing an alternate coupling embodiment

• of the present invention. [0028] Figure 15 is a cross-sectional isometric view showing a different alternate coupling embodiment of the present invention.

[0029] Figure 16 is a cross-sectional isometric view showing the present impact pad with a mono-hardness cushion.

[0030] Figure 17 is a photograph showing the composite impact pad in Figures 4-1 1 after actual use on a horse.

[0031] Figure 18 is an enlarged portion of composite impact pad shown in the photograph of Figure 17.

[0032] Figure 19 is an isometric view similar to Figure 4, showing an improved impact pad.

[0033] Figure 20 is a view similar to Figure 5 showing the retainer member of the improved laminated impact pad.

[0034] Figure 21 is a view similar to Figure 6 showing the cushion member of the improved impact pad.

[0035] Figure 22 is a view similar to Figure 7 showing one half of the improved impact pad bonded to a horseshoe.

[0036] Figure 23 is a view similar to Figure 13B showing the cushion member of the improved impact pad coupled to a retainer member integral with a horseshoe.

[0037] Figure 24 is a view showing an exemplary process for liquid casting a preferred dual-hardness polyurethane blank used to make cushion members.

[0038] Figure 24A is an isometric view showing multiple cushion members on a blank.

[0039] Figure 24B is an isometric view showing multiple alternate cushion members on a blank.

[0040] Figure 24C is an isometric view of an enlarged portion of a liquid cast multiple- hardness polyurethane blank.

[0041] Figure 25 is an isometric view showing multiple retainer members on a blank.

[0042] Figure 26 is an isometric view of a process for assembling an impact adsorbing horseshoe.

[0043] Figure 27 is an isometric view of a process for assembling an alternate impact adsorbing horseshoe embodiment.

[0044] Figure 28 is an isometric view showing present invention used with a combination full plate insert and horseshoe.

[0045] Figure 29 is an isometric view showing present invention used with a combination spider plate insert and horseshoe.

[0046] Figure 30 is an isometric view showing present invention used with a combination bar plate insert and horseshoe.

DETAILED DESCRIPTION OF THE INVENTION

[0047] Referring to the drawing figures, Figure 1 is a schematic representation showing the plantar surface of a horse hoof 1. The hoof of a horse comprises three broadly defined areas comprising the toe 2, the quarter 3, and the heel 4. The quarter and heel areas can be further defined by a right quarter and left quarter 3a and 3b respectively, and a right heel 4a and a left heel 4b. The right quarter 3a and right heel 4a are shown on the left side of the drawing figure because Figure 1 is a bottom plan view of horse hoof 1. A hoof wall 5 extends along the toe 2 area and quarter areas 3a and 3b to a location proximate bulbs 6 that are located within the right and left heel areas 4a and 4b respectively. The hoof wall includes an anterior side 5a and a posterior side 5b adjacent a white line 7 that encircles sole 8 of the hoof. The hoof further includes a frog 9 having and median groove 9a positioned between bars 10. [0048] Referring to Figure 2 and Figure 3 labeled "Prior Art," various impact absorbing impact pads have been developed in the past to reduce the concussive force generated by the shock of impact when a horse hoof strikes the ground. For example, United States patent 6,497,293 B1 to Miller, 5,505,264 to Morris, et al., and United States patents 5,137,093 and 5,029,648 to Stephens show impact absorbing impact

pads made from various resilient materials. As heretofore mentioned above, such impact pads are nailed, bonded, or both nailed and bonded to the hoof. In the prior art example shown in Figures 2 and 3, impact pad 11 is attached to hoof 1 by driving nails 12 through holes 13 provided in the horseshoe 21. The top surface 14 of impact pad 11 extends between an anterior side 15 and posterior side 16 of the impact pad, and top surface 14 is positioned against the plantar surface of a horse hoof 1. Nails 12 are driven directly through impact pad 11 and into the hoof wall 5 to fasten the horseshoe and impact pad to the hoof.

[0049] Referring specifically to Figure 2, hoof 1 is shown positioned above the ground 17 just before hoof 1 strikes the surface of the ground. When a horse moves at a fast gait, for example a trot, pace, gallop or run, the hoof rotates through a rapid complex movement called breakover. The term breakover refers hoof biometrics associated with the rotation of the hoof where the hoof heel strikes the ground first, then the entire plantar surface contacts the ground, and finally the toe lifts off the ground for the next stride. For example, referring to Figure 3, when the rotating horse hoof 1 strikes the ground 17, the heel 4 normally impacts the ground slightly before the toe 2 makes contact. Such "heel first" contact causes shear in an outward direction as shown by arrow 18 and force is transmitted to the nailed and/or bonded connections that fasten the horseshoe 21 and impact pad 11 to hoof 1. On impact with the ground 17, the outward shear force 18 causes impact pad 11 to distort or elongate a distance "Z" depending on the amount of the applied force and the elasticity of the impact pad material. In a mechanical connection, where the horseshoe 21 and impact pad 11 are fastened to the hoof wall 5 with nails 12, the repeated shear and pad distortion "Z" tends to bend the nail shanks, as shown in Figure 3. Such lateral and/or transverse distortions of the impact pad causes shoe movement or wobble and the horseshoe becomes misaligned with the hoof 1. Over time, the continuous stress can shear the nailed connections and rip the horseshoe from the hoof. In a chemical connection, where the impact pad 11 is bonded to both the horseshoe 21 and to the hoof wall 5 with an adhesive, the horseshoe is suddenly sheared from the hoof without any prior warning as indicated by the shoe misalignment in a nailed connection.

[0050] Referring to Figures 4 through 8 showing a impact pad referred to in the art as a rim pad, the preferred embodiment of the present invention includes a composite impact pad 20 positioned between a horseshoe 21 and the plantar surface of a horse hoof 1 (Figures 9 and 10). Horseshoe 21 includes a top surface 22 normally placed

against the plantar surface of the hoof when a impact pad is not used, or as in the present invention, against the composite impact pad 20 positioned between the horseshoe 21 and the hoof. Horseshoe 21 further includes a bottom surface 23 that contacts the ground, a shoe anterior side 24, and a shoe posterior side 25. The top surface 22 is shaped to provide toe 2', a quarter 3 ¹ , and a heel 4' areas that correspond with the toe, quarter, and heel areas of the hoof shown in Figure 1 , including a right quarter and left quarter 3a ¹ and 3b ¹ respectively, and a right heel 4a' and a left heel 4b'. [0051] The composite impact pad 20 also comprises toe, quarter, and heel areas 2', 3', and 4' that correspond with the like horseshoe areas, and the composite impact pad includes a retainer member 26 and a mono-hardness cushion member 27. The retainer and cushion members are molded or extruded separately from different materials, as shown in Figures 6 and 7, and then bonded together with an adhesive and to the top surface 22 of the horseshoe to provide a completed composite impact pad 20 positioned between the horseshoe and hoof. In the preferred embodiment, retainer member 26 is manufactured from a rubber, plastic or other similar material having a shore hardness greater than about 80 shore on a durometer scale with a preferred hardness of between about 85-95 shore. The cushion member is manufactured from gum rubber or the like and it has a hardness of 70 shore and lower with a preferred hardness range between about 60 to about 65 shore. Alternatively, cushion member 27 may be a liquid cast multi-hardness polyurethane comprising at least two different hardness bonded laminae of as shown in Figure 24A, the preferred dual-hardness cushion material, or as shown in 24C, an alternate cushion material having at least three different hardness bonded laminae.

[0052] The retainer member 26 (Figures 4-5 and 7-8) includes a top surface 28, bottom surface 29, an anterior side 30, and a posterior side 31 that is shaped to couple to cushion member 27. The posterior side also includes elongated opposed terminus end portions 36a and 36b that extend a length "Y" into the heel areas 4a' and 4b' of composite impact pad 20 when coupled to the cushion member. In the preferred embodiment, length "Y" measures between about 0.5 to about 0.625 inches. This provides a long fade or transition between the harder retainer material and the softer cushion material, the long fade extending from the quarter area 3" into the heel area 4" of the composite impact pad 20.

[0053] Similarly, cushion member 27 (Figures 4 and 6-8) has a top surface 32, bottom surface 33, a posterior side 35, and an anterior side 34. The anterior side 34

includes a shaped portion 37 that corresponds with, and couples to, the shaped posterior side 31 of the retainer member, including the terminus end portions 36a and 36b that extend into the heel areas 4a ¹ and 4b' of composite impact pad. Referring to Figure 4, the coupled posterior side 31 , and anterior side 34 comprise a mitered joint 38 connection. The mitered joint extends in a posterior downward direction from the retainer member top surface 28 to its bottom surface 29 so that mitered retainer member 26 extends under and supports a portion of the cushion member 27. As shown in Figure 8, mitered joint length "X" at toe area 2" is smaller than mitered joint length "Y" at the terminus end portions 36a and 36b.

[0054] During use, concussive forces are transferred from the horseshoe into the composite impact pad 20. The shock absorbing material used for cushion member 27 dampens the impact of forces received from the horseshoe while the harder retainer member 26 transfers such incoming concussive forces into the softer cushion member through the mitered joint connection 38. The transfer of forces from the retainer member 26 into the cushion member 27 takes place along the mitered surface of the retainer member that extends beneath the cushion member along joint 38. In addition, the abutting surface of retainer member 26 along the mitered joint connection 38 prevents cushion member distortion as shown in Figure 3 where the prior art impact pad distorts a distance "Z" in response to the hoof striking the ground. [0055] Horseshoes come in various shapes and sizes and the composite impact pad of the present invention may be manufactured to fit any selected shoe configuration with the retainer member being shaped to coincide with the nail pattern of the selected horseshoe. Accordingly, Figures 7 and 8 show a coupled composite impact pad 20 of the present invention fixed to a selected horseshoe. The retainer member 26 and cushion member 27, shown separately in Figures 5 and 6, are coupled together along mitered joint 38 that extends from the retainer terminus end 36a, through the toe area 2, to terminus end 36b. Retainer member 26 is shaped to coincide with and to cover the nail pattern defined by spaced apart nail holes 13 extending through the horseshoe 21 (Figure 7), and the retainer member 26 may include corresponding nail holes 13' to facilitate nailing the combination horseshoe and hoof-pad to the hoof wall. [0056] Referring to Figures 9, 10, and 11 , showing the preferred composite impact pad 20 positioned on a hoof, the horseshoe is removed in Figure 11 for clarity, a first adhesive is applied to the top surface 22 of horseshoe 21 and to one half of mitered joint 38, either the retainer member half or the cushion member half. After the first

applied adhesive is dry, a second adhesive is applied to the bottom surfaces 29 and 33 of the retainer member and cushion member respectively and to the remaining half of mitered joint 38, the half that did not receive the first applied adhesive. While the second adhesive is still wet, the adhesive coated bottom surfaces 29 and 33 are placed onto the dry first adhesive coated top surface 22 of the horseshoe and positioned so that the retainer and cushion members are coupled or interlocked along the adhesive coated mitered joint 38. After the adhesive bond is cured to its full strength, nails are inserted into the nail holes 13 and 13' and they are driven into the hoof wall 5 that extends along the periphery of hoof 1 shown in Figures 1 and 11. In the present invention, the preferred first applied adhesive is a viscous liquid contact type cement and the preferred second applied adhesive is a cyanoacrylate adhesive. However, any suitable chemical bonding system known in the art may be used to couple and affix the composite impact pad assembly 20 to the top surface 22 of horseshoe 21 without departing from the scope of the present invention.

[0057] Additionally, although the preferred embodiment shows nail holes 13" extending through retainer member 26 to facilitate nailing the horseshoe and composite impact pad to the hoof wall, Figure 4 shows the retainer member 26 without nail holes. In such an arrangement, nails may be inserted into the nail holes 13 and the nails are driven through retainer member 26 into the hoof wall to mechanically attach the horseshoe and composite impact pad retainer member to the hoof wall. Alternatively, in such a composite impact pad assembly 20 without nail holes, the impact pad may be chemically bonded to the horseshoe and hoof wall with a suitable adhesive, without nailing.

[0058] Referring again to Figures 9 and 10, the shaped or mitered portion 38 that extends along the anterior side 34 of cushion member 27 in Figure 6, is captured within bounds defined by the retainer shaped posterior side 31 the planter surface of hoof 1 , and the top surface 22 of the horseshoe 21. The harder and less resilient retainer member 26 that is fixed to the horseshoe and hoof wall provides a barrier that prevents the softer and more resilient cushion member 27 from distorting in response to the shock of impact when the hoof strikes the ground. Accordingly, the above mentioned problems associated with prior impact pad arrangements, where the impact pad distorts or stretches a distance "X" (Figure 3) in response to the shock of impact, is eliminated. This reduces or eliminates shoe movement giving the horse greater stability when it pushes off on the harder retainer member that spans the toe area of

the hoof. It also prevents nail break-off and thereby eliminates hoof wall damage associated with shoe loss, where sections of the hoof wall are torn away as the shoe is ripped from the hoof.

[0059] Figures 12, 13A, 13B, 14, and 15, show alternate embodiments of the present impact pad invention. Referring now to Figure 12, the alternate embodiment is a full pad 40 that covers the entire planter surface of hoof 1. The alternate composite impact pad 40 is shown positioned on hoof 1 with the horseshoe removed for clarity. In the full pad embodiment, the physical properties and structural features are similar to the physical properties and structural features described above for the preferred retainer member 26 and the preferred cushion member 27. The full pad, cushion member 42 is coupled to retainer member 41 along joint 43, and cushion member 42 spans the right and left quarters 3a and 3b, and ^' the right and left heels 4a and 4b respectively so that the sole 8 and frog 9 of the horse hoof are covered and protected by cushion member 42. Nail holes 13' corresponding to the nail pattern may be provided in retainer member 41. The composite impact pad members 41 and 42 are bonded to the horseshoe and to each other as described above, and the combination horseshoe and full composite impact pad 40 may be either mechanically or chemically fastened to the hoof wall, or both. Alternatively, cushion member 42 may be a liquid cast multi-hardness polyurethane comprising at least two different hardness bonded laminae of as shown in Figure 24A, the preferred dual-hardness cushion material, or as shown in 24C, an alternate cushion material having at least three different hardness bonded laminae. [0060] Referring to the alternate embodiment in Figures 13A and 13B, a metallic retainer member 45 is manufactured as an integral component of the horseshoe 44 to provide an in-situ retainer member 45 adapted to receive and couple to cushion member 27 (Figure 6) or the like. Accordingly, horseshoe 44 includes a retainer top surface 46 positioned at an elevation above the horseshoe top surface 47, and the posterior side 48 of the in-situ retainer member 45 is shaped to couple to or interlock with the shaped portion 37 of the cushion member 27. The shaped portion of the in- situ retainer member 45 extends below and supports cushion member 27 to transfer concussive forces from the retainer member into the cushion member. Cushion member 27 is bonded to the horseshoe top surface 44 as heretofore described, and nail holes 13 extend through the retainer member portion of the horseshoe to fasten horseshoe 44 to a hoof wall. Alternatively, the horseshoe may be attached to the hoof

wall by chemically bonding top surface 47 to the hoof wall, or by both mechanically fastening and chemically bonding top surface 47 to the hoof wall. [0061] It should be understood that although the preferred embodiment shows a mitered joint connection 38 being used to couple the retainer and cushion members 26 and 27 of the composite impact pad 20, any suitable coupling arrangement may be used to interlock the retainer and cushion members without departing from the scope of the present invention. For example, referring to the alternate embodiment in Figure 14, a half-lap joint 38a is used to couple the retainer member 26a and cushion member 27a of the composite impact pad 20a. The interlocking joint includes a vertical surface 50 that extends in a downward direction from retainer member top surface 28a and intersects inclined surface 52 that extends in a posterior downward direction to bottom surface 29a so that the inclined surface 52 extends under and supports a portion of the cushion member 27a. Retainer member is shaped to coincide with and cover the nail pattern provided by the spaced apart nail holes 13 that extend through horseshoe 21a. Cushion member 27a includes an inclined surface 53 that extends in both an upward and an anterior direction from the cushion member bottom surface 33a so that inclined surface 53 overlaps a portion of retainer member 26a and intersects vertical surface 51 extending downward from the cushion member top surface 32a. The interlocked lap joint 38a is fixed by adhesive bonding, and the bottom surfaces 29a and 33a are adhesive bonded to the top surface of a horseshoe 22a. When the composite impact pad 20a is assembled, inclined surface 50 is positioned below inclined surface 51 so that the concussive forces generated by each hoof beat are transferred from the horseshoe 21a into retainer member 26a and into cushion member 27a through interlocked surfaces 50 and 51. In addition, because the harder retainer member 26a abuts the corresponding interlocked portion of the softer and more flexible cushion member 27a the retainer member prevents the cushion member from distorting in response to the shear forces generated by the shock of impact when the hoof strikes the ground.

[0062] Figure 15 shows another alternate coupling mechanism embodiment used to interlock the retainer and cushion members 26b and 27b of composite impact pad 20b. In this alternate embodiment, the retainer member coincides with, and covers the nail pattern defined by spaced apart nail holes 13 that extend through horseshoe 21 b. Retainer member 26b is shaped to provide a groove 54 that extends along the posterior side 31 b between terminal end portions similar to 36a and 36b of the retainer

member shown in Figure 8. Likewise, the anterior side 34b of cushion member 27b includes a tongue 55 that extends along a shaped portion similar to shaped portion 37 shown in Figure 6. When coupled together, the posterior side 31b and anterior side 34b provide a tongue and groove joint 56. The interlocked tongue and groove joint 56 is chemically bonded with a suitable adhesive, and the bottom surfaces 29b and 33b are chemically bonded with a suitable adhesive to the top surface 22b of a horseshoe 21b as heretofore described above. The retainer member portion of the coupled tongue and groove joint 56 includes an extended bottom leg 57 that extends under and supports a portion of the cushion member 27b so that the retainer member transfers concussive forces into the softer more resilient cushion member 27b when the horseshoe strikes the ground. Figures 14 and 15 are only two exemplary coupling arrangements that could be used to interlock the retainer and cushion members of the present composite impact pad invention without departing from the scope of the present invention.

[0063] Figure 16 shows a retainer member 61 and a mono-hardness cushion member 62 chemically or molecularly bonded together along a joint line 63. The mono- cushion member has a hardness between about 40 and about 65 shore with a preferred hardness of about 55 shore, and the retainer member has a hardness greater than about 80 shore with a preferred hardness between about 85 and about 90 shore. Retainer member 61 is shaped to coincide with and cover the nail pattern in any given horseshoe 64. The composite impact pad 60 is chemically bonded to the top surface 65 of the horseshoe as described above. The harder retainer member prevents cushion distortion when concussive forces generated by the impacting hoof are transferred from horseshoe 64 into cushion member 62.

[0064] Referring to the composite impact pad shown in the photographs labeled Figures 17 and 18, what was believed to be the preferred embodiment of the present invention, shown in the above Figures 4-11 , was reduced to actual practice by using the composite pad 20 on horses competing in thoroughbred, harness races, and other completive events. It was discovered that the gum rubber cushion member 27 failed to provide satisfactory service life due to the continuous pounding it received during such events. However, it was observed that the retainer member 26 was able to withstand the intense pounding received from the impacting hooves, and the retainer successfully prevented nail shear. The photographs in Figures 17 and 18 show damaged areas 66 where substantial portions of cushion member 27 were torn away during the different

events, and the horses required new shoes in approximately two days from shoeing with the composite impact pads.

[0065] As a result of the above problem, extensive research was conducted and the improved impact pad as shown in Figures 19-30 was developed. Referring in particular to Figure 19-22, the improved impact pad 70 is positioned between a horseshoe 71 and the plantar surface of a horse hoof 1 as shown in Figures 9 and 10. Horseshoe 71 includes a top surface or hoof-side 72 normally placed against the plantar surface of the hoof when a impact pad is not used. In the present invention, surface 72 is placed against impact pad 70, and the impact pad is placed against the plantar surface of the hoof. Horseshoe 71 further includes a bottom surface 73 that contacts the ground, a shoe anterior side 74, and a shoe posterior side 75. Referring in particular to Figure 22, showing one half of an impact pad 70 bonded to the top surface 72 of a horseshoe 71 the top surface 72 shoe is shaped to provide toe 2', quarter 3', and heel 4' areas that correspond with the toe, quarter, and heel areas of the of the improved impact pad 70. The quarter area of both the horseshoe and the improved impact pad is further defined by a right quarter 3a ¹ and a left quarter 3b ¹ . Similarly, the heel areas are further defined by a right heel 4a' and a left heel 4b'.

[0066] The improved impact pad includes a retainer member 76 and a cushion member 77. The retainer and cushion members are molded or extruded separately as shown in Figures 20 and 21 , and then are bonded together with an adhesive along a coupled joint 88a. Retainer member 76 is manufactured from a thermal set polyurethane material having a hardness greater than about 80 shore as measured on a shore durometer, with a preferred hardness of between about 85-95 shore. It should be understood that retainer member 76 may be manufactured from any suitable natural or other synthetic material having a shore hardness greater than 80 without departing from the scope of the present invention.

[0067] Referring again to Figure 19, cushion member 77 is a liquid cast multi-hardness polyurethane material comprising a first lamina 78 bonded to a second lamina 79 during casting, the bonded laminae providing a preferred dual-hardness cushion member. The first lamina is manufactured from a liquid cast polyurethane having a hardness between about 40-60 shore with a preferred hardness of about 55 shore. Lamina 78 includes a bottom surface 80 that bears against top surface 72 of the horseshoe, and an top surface 81 bonded to the second lamina 79 during the liquid cast process. Lamina 79 comprises a liquid cast polyurethane having a hardness greater than about 80 shore with a preferred

hardness between about 85-95 shore. In the preferred embodiment, lamina 79 is identical to the material used to manufacture the retainer member 76. However, retainer 76 may be cast from a different material having the same shore hardness and abrasion resistance without departing from the scope of the present invention. [0068] Referring again to Figures 19-22, retainer member 76 is similar in shape to the retainer shown in Figures 4-5 and 7-8 in that retainer member 76 includes a top surface 82, bottom surface 83, an anterior side 84, and a posterior side 85 shaped to couple to cushion member 77 along coupled joint 88a. In addition, retainer member 76 is shaped to overlap the nail pattern provided by apertures 13 extending through horseshoe 71 so that the retainer member provides a nailing edge for attaching the improved impact pad to the hoof. Although it is not necessary, the retainer member may also include apertures or nail holes 13' that correspond with the nail holes in horseshoe 71.

[0069] Similarly, the liquid cast dual-hardness polyurethane cushion member 77 includes a top surface 87 defined by lamina 79 and a bottom surface 80 defined by lamina 78, an anterior side 88, and a posterior side 89. The anterior side 89 includes a shaped portion 90 that corresponds with, and couples to the shaped posterior side 85 of the retainer member along coupling joint 88a.

[0070] During use, concussive forces are transferred from horseshoe 71 into the improved impact pad 70. Retainer member 76 stabilizes the fasteners or nails that fix the horseshoe and retainer member to the hoof so that the nails do not sear in response to forces generated by the shoes impacting on the ground or track as heretofore described and shown above in the prior art Figures 2 and 3. The first lamina 78 in cushion member 77 dampens the concussive forces generated by the impacting horseshoe while the second lamina 79 prevents the horse hoof from tearing and destroying the cushion member as shown in the Figure 17 and Figure18 photographs of the earlier embodiment.

[0071] Referring to Figure 23, and as heretofore mentioned above, the retainer member may be formed as an integral part of a horseshoe 44. In such an alternate, the metallic retainer member 45 provides an in-situ retainer member that is adapted to receive and couple to the liquid cast dual-hardness cushion member 77 of the present invention. Accordingly, horseshoe 44 includes a retainer top surface 46 positioned at an elevation above the horseshoe top surface 47, and the posterior side 48 of the in- situ retainer member 45 is shaped to couple to or interlock with the shaped portion 90

of cushion member 77 including the first lamina and second lamina 78 and 79 respectively.

[0072] Referring to Figures 24, 24A, and 24B, dual hardness polyurethane blanks or sheets 91 are produced in a continuous or batch liquid casting operation. The liquid cast polyurethane sheets comprise a first lamina 78 bonded to a second lamina 79 during the liquid casting process. Lamina 78 has a hardness between about 40-60 shore with a preferred hardness of about 55 shore, and the second lamina 79 has a hardness greater than about 80 shore with a preferred hardness between about 85-95 shore. Figure 24 shows an exemplary continuous caster 102 where the first lamina 78 is cast from a resin supply contained in hopper 103 and the second lamina 79 is cast from a resin supply contained in hopper 104. The cast laminae 78 and 79 pass between twin caster rolls 105 and 106 during curing and bonding. After curing, the cast product is sheared to size to provide the laminated blank or stock material 91 shown in Figures 24A and 24B. While Figure 24 shows lamina 78 being cast at an earlier time with respect to lamina 79, any lamina casting order, in either a continuous or batch process, may be used without departing from the scope of the present invention. After the dual hardness polyurethane sheets are cured, a plurality of dual-hardness cushion members 77 are stamped from the polyurethane sheets 91 as shown in Figure 24A. Alternatively, as shown in Figure 24B, a plurality of dual-hardness full pad cushion members 92 may be stamped from the cured sheets 91. The full pad cushion members 92 include a shaped portion along the anterior side of the cushion member so that it couples to the shaped posterior side of the retainer member along coupling joint as shown in Figure 27. Referring to Figure 25, the preferred retainer members 76 are stamped from a liquid cast polyurethane sheet 93 having a hardness greater than about 80 shore with a preferred hardness between about 85-95 shore. In both instances, the preferred liquid cast dual-hardness polyurethane sheet 91 for cushion pads 77 and 92, comprise a first lamina 78 having a thickness between about 3/32 and about 5/32 inches (about 0.2381 and about 0.3969 cm) with a preferred thickness of about 1/8 inch (about 0.3175 cm), and a second lamina 79 between about 1/64 and about 3/64 inches (about 0.0397 and about 0.1 191 cm) with a preferred thickness of about 1/32 inch (about 0.0794 cm). This provides a dual-hardness polyurethane cushion pad having a total thickness between about 7/64 and about 13/64 inches (about 0.2778 and about 0.5159 cm) with a preferred total thickness of about 5/32 inch (about 0.3969 cm). Retainer members 76 have a thickness that corresponds to the total thickness of the cushion pads 77.

[0073] Cushion members 77 and 92 may be manufactured from a liquid cast multi- hardness polyurethane sheet having more than two laminae. Figure 24C shows cushion members 77a being made from a liquid cast multi-hardness polyurethane sheet 91a where the first lamina 78 is sandwiched between the second lamina 79 and a third lamina 79a. The total thickness of the multi-hardness cushion pads 77a corresponds with the total thickness of the dual-hardness cushion pads 77, and the shore hardness of lamina 79a is greater than about 80 shore with a preferred hardness between about 85-95 shore. [0074] The shaped posterior side 85 of the retainer members 76 and the shaped portion 90 extending along the anterior side 88 of the dual-hardness cushion member 77 are coated with an adhesive as shown in Step A of Figure 26. The adhesive coated members 76 and 77 are bonded together along coupling joint 88a (Step B) to provide an assembled dual-hardness impact pad 70 for use on a horseshoe 71. The bottom surfaces of the assembled members 76 and 77 are coated with an adhesive and the dual-hardness impact pad 70 is bonded to the top surface 72 of horseshoe 71 as shown in Step C.

[0075] Likewise, referring to Figure 27, shaped posterior side 85 of the retainer members 76 and the shaped portion 90a along the anterior side 94 of the alternate dual-hardness cushion member 92 are coated with an adhesive as shown in Step A, and the adhesive coated portions 85 and 90a are bonded together along coupling joint 94a at Step B to provide a full dual-hardness impact pad 95 for use with various horseshoe/insert plate combinations well known in the art. Three such insert plate combinations shown in Figures 28-30.

[0076] Referring specifically to Figure 28, a full dual-hardness impact pad 95 is bonded to the top surface of a full plate insert 96 that is bonded to the top 72 of a horseshoe 71. Such full plate inserts are used to stabilize a hoof and the completed impact adsorbing horseshoe/insert plate combination 97, comprising a the full dual- hardness impact pad 95 prevents nail shear and dampens the concussive forces generated by impacting hooves as described for Figures 19-22. [0077] Referring to Figure 29, a full dual-hardness impact pad 95 is bonded to the top surface of a spider plate insert 98 that is bonded to the top 72 of a horseshoe 71. Such spider plate inserts are used to protect the frog portion 9 of a hoof (Figure 1 ), and the completed impact adsorbing horseshoe/insert plate combination 99 comprising a full dual-hardness impact pad 95 prevents nail shear and dampens the concussive forces generated by impacting hooves as described for Figures 19-22.

[0078] Referring to Figure 30, a full dual-hardness impact pad 95 is bonded to the top surface of a bar plate insert 100 that is bonded to the top 72 of a horseshoe 71. Such bar plate inserts are used in instances where additional support is needed for the horse. The completed impact adsorbing horseshoe/insert plate combination 101 comprising full dual-hardness impact pad 95 prevents nail shear and dampens the concussive forces generated by impacting hooves as described for Figures 19-22. [0079] It should be noted that the present invention is not limited to use with the horseshoe insert plate examples shown in Figures 28-30, and that the full dual- hardness impact pad 95 of the present invention may be used with other horseshoe inserts known in the art without departing from the scope of the present invention. [0080] As such, the present invention has been disclosed in terms of preferred and alternate embodiments that fulfill each one of the objects set forth above, and the invention provides a new and improved impact pad that reduces the shock of impact when a hoof strikes the ground, and eliminates impact pad distortion that causes the horseshoe shear. Of course, those skilled in the art may contemplate various changes, modifications, and alterations from the teachings of the present disclosure without departing from the intended spirit and scope of the present invention.