STIRRUP SUSPENSION

Abstract: An improved stirrup suspension (10) utilizes a multi-stage spring suspension to accommodate the different downward forces generated during normal riding as well as jumping. The stirrup suspension includes a housing (12) having a bottom wall (24) and continuous side wall (26), a plunger (14) slidably received within the housing (12), a stirrup connector (16) mounted to the lower end of said plunger, a first spring element (18) received around the plunger, and a second spring element (20) also received around said plunger. The first spring element (18) is effective for exerting a force F1 under a minimum load while the second spring element (20) is effective for exerting a force F2 that is greater than F1 under a minimum load. In use, the lower end of the plunger (14) is attached to the stirrup which will move up and down relative to the housing. The plunger (14) slidably moves within housing (12) where a flange member (52) at the top of the slide compresses the first and second spring elements (18, 20) upon the exertion of a downward force on the stirrup.

Description: STIRRUP SUSPENSION Cross-Reference to Related Applications: This application is related to co-pending application No. 09/436,574, filed November 19, 1999. Background and Summary of the Invention: The instant invention relates to horse back riding, and in particular relates to a stirrup suspension including a first suspension spring designed to absorb the downward forces attendant to normal riding conditions, and a second more rigid suspension spring designed to absorb the additional downward forces developed during jumping. Typical equestrian riding gear includes a saddle, and stirrups attached to the saddle for receiving the feet of a rider. The weight of an individual seated upon the saddled horse is distributed through the saddle and the stirrups. In forward motion of the horse, the rider's feet in the stirrups act as a natural suspension system through flexion of the ankle joints. The rider places the ball of his foot on the base of the stirrup and by the controlled flexion of the ankle joint, the rider can create a natural suspension system. This type of riding is most prevalent in English riding, and especially in jumping. Sufficient suspension of the rider is necessary to maintain proper balance for performance purposes as well as safety. In addition, proper suspension avoid unnecessary adverse contact of the rider on the horse's back thereby avoiding injury to the horse. In jumping, the problem is compounded by increased vertical forces generated by vertical movement of the rider's weight, and a concentration of those forces directly through the stirrups. The amount of downward pressure on the stirrups is dependent upon the rider's weight, forward momentum, position, the amount of contact in the seat of the saddle and the height of the jump. The amount of downward forces increases dramatically upon take-off and landing. Accordingly, an individual needs to physically create sufficient natural suspension in two stages: 1) when approaching a jump or shortly after landing; and 2) at take-off and landing of the jump. In stage 1, for example, a 160 lb. rider might create between 25 and 125 lbs./sq.in. of downward force in each stirrup depending on body contact in the saddle. However, when jumping, the rider disperses the weight primarily through the stirrups and generates a significantly higher downward force, which depending on the height of the jump and weight of the rider, can reach up to 300 lbs./sq.in. The forces generated during riding and jumping should be absorbed through the ankle's natural suspension. However, the drawback to the ankle's natural suspension is that is relies on the physical limitations of the rider. Effectiveness in executing this riding style depends highly on physical flexibility, range of motion, strength, posture, and experience of the rider. Insufficient flexibility and range of motion will clearly result in inferior riding, loss of balance, and potential injury to the horse and/or rider. This is especially apparent in show jumping. In competitive show jumping, a rider navigates around a course containing several jumps, usually more than a dozen, which are set at prescribed heights depending upon the qualifications of the rider. Therefore, in this environment a rider would encounter both normal riding conditions and jumping conditions rapidly interchanging and would experiences frequent and substantial variations in downward force. Rider's with poor ankle control and flexion are often referred to as having "stiff ankles." The most frequent recommendation to improve strength and flexibility is physical therapy, that is exercises to both strengthen the ankle and calf muscles and to stretch the Achilles tendon to expand range of motion. The prior art has also attempted to provide a variety of energy absorbing devices to remedy the "stiff ankle" problem. These devices have included stirrup suspensions with springs and shock absorbers. While these solutions are effective in some specialized circumstances, they have not yet been widely adopted in the art, and there is thus believed to be a need in the industry, and especially for competitive show jumping, for an improved multi-stage stirrup suspension that can accommodate the different downward forces generated during normal riding as well as jumping. In this regard, the instant invention provides an improved stirrup suspension that utilizes a multi-stage spring suspension to accommodate the different downward forces generated during normal riding as well as jumping. The stirrup suspension includes a housing, a plunger slidably received within the housing, a stirrup connector mounted to the lower end of the plunger, a first spring element received around the plunger, and a second spring element also received around said plunger. The first spring element is effective for exerting a force Fi that would be typical of the force exerted during normal riding, while the second spring element is effective for exerting a force F 2 that is greater than Fi that would be typical of the greater force exerted during jumping landing and take-off. In this regard, it is noted that in stadium jumping, participants compete in different jumping height divisions. For example, there is a 3 '6" jump height division, a 4'3" jump height division, etc. Within each division, all of the jumps are relatively the same height. With the factors of rider weight and jumping height being substantially constant, the spring elements can be individually selected and customized according to a rider's weight, height of jumps, and riding style. This is highly advantageous for marketing and sales purposes. Turning back to the suspension, the lower end of the plunger is attached to the stirrup via a stirrup connector. During riding, the stirrup will move up and down relative to the housing with the plunger slidably moving within housing. A flange member at the top of the plunger compresses the first and second spring elements upon downward movement corresponding to the exertion of a downward force on the stirrup. During normal riding, the first spring is compressed to counter the downward forces exerted. The first spring will be compressed from a minimum load to a maximum load. However, when forces exerted during jumping exceed a percentage of the maximum force (load) on the first spring under compression, the second spring begins to compress to exert additional counter forces. The second spring will thereafter exert forces through its range of minimum compression to maximum compression. In a first embodiment, the springs are concentrically configured around the plunger. The first, i.e. inner spring, has a longer length, and smaller diameter. The second spring has a shorter length and wider diameter and is received around the first spring. In operation, the flange first compresses the first spring through a range of motion. When the forces are great enough to compress the first spring through a predetermined range of compression, the flange then engages the second spring and begins compressing the second spring. In this regard, the first and second springs are simultaneously compressed and cooperate to exert a combined force against the flange. In a second embodiment, the first and second springs are of the same length and diameter and are stacked one upon the other, the upper spring comprising the first spring and the lower spring comprising the second spring. In this regard, the first and second springs actively cooperate to exert forces against the flange and both are active at all times, in contrast with the first embodiment where the first spring is active to a certain point and then the second spring becomes active to cooperate with the first spring. In further embodiments, the first and second springs are pre-loaded in compression to provide a smooth spring action during use. Accordingly, among the objects of the instant invention are: to provide a stirrup suspension for the rider of a horse to create additional suspension over and above what can be achieved physically through the flexion of the ankles; to provide a stirrup suspension that can be customized to individual needs based on body weight and height of jumping; to provide a multi-stage stirrup suspension to accommodate the different levels of downward force that occur during normal riding and jumping; to provide a stirrup suspension that is independent of the stirrup; to provide a stirrup suspension that improves the rider's balance, performance and personal safety; to provide a stirrup suspension that reduces harmful contact with the horse's back; to provide a stirrup suspension that reduces the structural breakdown of the stirrup strap; and to provide a stirrup suspension that reduces strain on the muscle, cartilage and ligaments of the rider's knees, ankles and calves. Other objects, features and advantages of the invention shall become apparent as the description thereof proceeds when considered in connection with the accompanying illustrative drawings. Description of the Drawings: In the drawings which illustrate the best mode presently contemplated for carrying out the present invention: Fig. 1 is an elevational view of the stirrup suspension of the present invention; Fig. 2 is a cross-sectional view thereof as taken along line 2-2 of Fig. 1; Fig. 2 A is another cross-sectional views thereof showing compression of the springs; Fig. 3 is an exploded perspective view thereof; Fig. 4 is a cross-sectional view of an alternative spring configuration; Fig. 5 is a cross-sectional view of a third embodiment showing pre-loading of the springs; and Fig. 6 is a cross-sectional view of a fourth embodiment also showing pre- loading of the springs. Description of the Preferred Embodiment: Referring now to the drawings, a first embodiment of a stirrup suspension constructed in accordance with the teachings of the present invention is illustrated and generally indicated at 10 in Figs. 1-3. As will hereinafter be more fully described, the instant stirrup suspension 10 provides an improved apparatus that utilizes a multi-stage suspension system to accommodate the wide range of downward forces generated during normal riding and jumping. Unless otherwise specified herein, it is to be understood that each of the constituent elements of the present stirrup suspension are preferably constructed or fabricated from a metallic material. Alternatively, certain elements of the structure could be molded from plastic. However, certain structural integrity and durability issues may preclude certain elements from being constructed from plastic or other materials. The stirrup suspension 10 includes a housing assembly generally indicated at 12, a plunger generally indicated at 14, a stirrup connector generally indicated at 16, a first spring element generally indicated at 18, and a second spring element generally indicated at 20. The housing assembly 12 includes a tubular container 22, preferably in the shape of a cylinder, having a bottom wall 24 and a continuous side wall 26 extending upwardly from the bottom wall 24. The container 22 is preferably no longer than about 3 inches in height and about 1.25 inches in diameter. The bottom wall 24 includes an axial opening 28. The housing assembly 12 further includes a yoke 30 which is removably mounted on the upper peripheral edge 32 of the side wall 26. To attach the yoke 30 to the container 22, the upper peripheral edge 32 of the side wall 26 and the inner side wall 34 of the body portion 36 of the yoke 30 are threaded for mating engagement. The upper surface of the yoke 30 includes a slotted formation 38 for connecting the saddle strap (not shown) to the yoke 30. The plunger 14 comprises an elongate rod portion 40 and a flange portion 42 mounted at the upper end of the rod portion. The plunger is slidably received within the housing assembly 12 with the lower end of the rod portion 40 extending downwardly and outwardly through the opening in the bottom wall. Connected to the bottom end of the rod portion 40 is the stirrup connector element 16. The stirrup connector 16 is generally T-shaped with the leg 44 of the connector 16 being threadably mounted to the lower exposed end of the rod portion 40 of the plunger 14. A stirrup connector strap 46 is mounted to the cross-bar 48 of the connector with fasteners 50. It is envisioned that the stirrup connector straps 46 can be made of various materials and can be fastened to the crossbar 48 in a variety of different ways. The first spring element 18 comprises a helical compression spring having a free length Lπ of approximately 3 inches, and a coil diameter D] of approximately 0.5 inch. The wire diameter di will vary according to the rider, and is selected to produce the desired forces at minimum and maximum compression according to conventional spring design formulas. In this regard, the first spring element is preferably effective for exerting a range of minimum and maximum forces Fi that would be typical of the range of forces exerted during normal riding. These forces generally range from about 25 psi to about 150 psi depending on the weight of the rider. A general range for a typical rider of 160 lbs. would be from about 50 psi to about 125 psi. These minimum and maximum forces are used in calculating the required spring length L, core diameter D, and spring wire diameter d. In assembly, the spring 18 is received around the rod portion 40 so that it is captured between the bottom wall 24 of the container 22 and the flange portion 42 of the plunger 14. More specifically, the upper end of the spring 18 engages a washer 52 that sits around the rod portion 40 of the plunger 14 adjacent to the flange portion 42. Downward movement of the plunger 14 will thereby compress the spring 18. The second spring element 20 also comprises a helical compression spring. However, this second spring is concentrically received around the first spring 18 (See Fig. 2). In this regard, the second spring 20 preferably has a shorter free length Lβ (approximately 2 inches) and a wider core diameter D 2 (approximately 1.0 inch). The wire diameter d 2 will vary and is selected to produce the desired forces at minimum and maximum compression. More specifically, the second spring element 20 is preferably effective for exerting a range of minimum and maximum forces F 2 (F 2 > Fi) that would be typical of the range of forces exerted during jumping. These forces generally range from about 50 psi to about 400 psi depending on the weight of the rider and jump height. A general range for a typical rider of 160 lbs. would be from about 150 psi to about 300 psi depending on the height of the jump. Since the housing assembly 12 is designed for easy disassembly, the spring elements 18 and 20 can be custom designed and installed according to the rider's weight, height of jumps, and riding style. In this regard, it should also be noted that the housing length and diameter, spring length, core diameter and wire diameter are all values that can be adapted to particular circumstances depending on changes in loading, deflection lengths of the spring, spring rates, desired size of the assembly, etc. With the factors of rider weight and jumping height being substantially constant in most cases, the spring elements can be individually selected and customized according to a rider's weight, height of jumps, and riding style. This is highly advantageous for marketing and sales purposes. The customization process can also be taken a step further to customized desired percentage loading. More specifically, in addition to customizing the device based on calculated FI and F2 force, it is contemplated that most riders would opt to accommodate only a percentage of the total force. For example, if the FI force was calculated to be a maximum of 150 psi, a rider could select to begin spring compression at 100 psi, and reach full stage 1 compression at 150 psi. Similar customization can be made with the F2 force and stage 2 compression. The above approach, which is only an example of the customization capability, would provide the rider with additional suspension capability other than what could be obtained through the flexion of the ankles, only when approaching the higher and more strenuous force levels. It is noted that the values provided herein are intended to represent examples as contemplated by the Applicant, and are not intended to limit the scope of the claims as defined hereinbelow. Referring now to Figs. 2 and 2A, during riding, the stirrup (not shown) will move up and down relative to the housing assembly 12 with the plunger 14 slidably moving up and down within housing assembly 12. The flange member 42 at the top of the plunger 14 compresses the first and second spring elements 18 and 20 upon downward movement corresponding to the exertion of a downward force on the stirrup. During normal riding, the first spring 18 is primarily active to counter the downward forces exerted. The first spring 18 will be compressed from a minimum load to a predetermined percentage of the maximum load (See Fig. 2 A). When forces exerted during jumping exceed the predetermined percentage of the maximum force (load) on the first spring 18 under compression, the second spring 20 begins to compress to exert additional counter forces. The second spring 20 will thereafter exert forces through its range of minimum compression to maximum compression. In other words, when the forces are great enough to compress the first spring 18 through a predetermined range of compression, the flange 42 then engages the second spring 20 and begins compressing the second spring. In this extended compression, the first and second springs 18, 20 cooperate to exert a combined force against the flange 42. It is noted that there will be a maximum point of compression of the first spring 18 where the coils of the first spring will engage and limit any further compression of the second spring. This theoretical "spring solid" position must be taken into account in overall design and selection of the springs 18, 20) so that the first spring 18 does not reach a solid condition too early in the compression of the outer second spring 20. Referring now to Fig. 4, a second embodiment of the stirrup suspension is illustrated and generally indicated at 10A. The construction of the housing assembly 12, slide element 14, and all other members is identical to the first embodiment 10 with the exception of the spring configurations 18 and 20. In the second embodiment 10 A, the first and second springs 18A and 20 A are generally of the same length L f and the same core diameter D and are stacked one upon the other. Springs 18 A and 20A are preferably separated by a washer 54. The upper spring 18A functions as the first spring 18 (lower spring rate) and the lower spring 20A functions as the second (higher spring rate) spring 20. The basic difference between these two springs 18A, 20A would likely be in the wire diameter d, with the second spring 20A having a larger wire diameter d to provide the higher spring rate needed. However, other configurations of the "stacked" spring embodiment are also possible. For example, the bottom spring 20A could have a wider core diameter D and/or have a different wire diameter d to provide a higher spring rate. In most cases the spring rates will be in different ranges, and there will be very little, if any, compression of the second spring until the forces reached the lower range of the second spring. For example, if the first spring is intended to move to full compression from 75 psi to 100 psi, and the second spring is designed to move to full compression from 200 psi to 250 psi, the second spring would not begin compression until the forces reached a minimum of 200 psi. It can be appreciated that many different combinations and customizations of the springs can be achieved with this type of construction. Referring now to Fig. 5, a third embodiment of the stirrup suspension is illustrated and generally indicated at 56. The present embodiment 56 is similar to the previous embodiment as shown in Fig. 4. However, the structure of the stirrup suspension 56 allows for pre-loading of the springs when assembled. Pre-loading of the springs is desirable with certain spring designs to overcome the initial forces necessary to begin compression of the spring. Where a particular compression range is desired in a spring, for example 100 psi to 150 psi, and the spring provided has a minimum compression value of 75 psi, it may be necessary to pre-load the spring to 100 psi to achieve the minimum value of the compression force desired. More specifically, the stirrup suspension 56 comprises a yoke 58, an outer tube 60, an inner tube 62, a plunger 64, a retaining ring 66, a washer 68, and upper and lower compression springs 70, 72. The upper spring 70 functions as the first spring (same as 18 A in Fig. 4)(lower spring rate) and the lower spring 72 functions as the second spring (same as 20A in Fig. 4)(higher spring rate). In assembly, the retaining ring 66 is received in the bottom of the outer tube 60, and the lower spring 72 is received on top of the retaining ring 66. The washer 68 is placed on top of the lower spring 72. The inner tube 62 is slidably received inside of the outer tube 60 to rest on top of the washer 68, and the upper spring 70 is received inside the inner tube 62 to sit on top of the washer 68. The plunger 64 is received through the center of the upper and lower springs 70, 72 and guided through an aperture in the retaining ring 66. A stirrup interface 74 is connected to the terminal end of the plunger 64 that extends through the retaining ring 66. The stirrup interface 74 provides for connection to the stirrup (not shown). The yoke 58 includes a downwardly depending collar 76 that is outwardly threaded. The threaded portion of the collar 76 is threaded into an inwardly threaded portion of the outer tube 60. As the collar 76 of the yoke 58 is threaded into the outer tube 60, the bottom edge of the collar 76 engages the upper lip of the inner tube 62 forcing the lower lip of the inner tube 62 into engagement with the washer 68 and ultimately compressing the lower spring 72 into a pre-loaded state. In this regard, the lower spring 72 is compressed between the bottom surface of the washer 68 and the upper surface of the retaining ring 66. Likewise, the yoke 58 engages with the flange 78 at the upper end of the plunger 64 and urges the plunger 64 downwardly to compress the upper spring 70 into a preloaded state where the upper spring 70 is compressed between the lower surface of the flange 78 of the plunger 64 and the upper surface of the washer 68. The yoke 58 further includes a floating pin 80 to provide for connection to the saddle straps (not shown). Referring now to Fig. 6, a fourth embodiment of the stirrup suspension is illustrated and generally indicated at 82. The present embodiment 82 is a nested spring embodiment similar to the embodiment shown in Figs. 1-3. As discussed in connection with the embodiment in Fig. 5, this embodiment 82 also allows for pre-loading of the springs when assembled. More specifically, the stirrup suspension 82 comprises a yoke 84, an outer tube 86, a plunger 88, a retaining ring 90, a guide stop 92, and inner and outer compression springs 94, 96. The inner spring 94 functions as the first spring (same as 18 in Fig. 2)(lower spring rate) and the outer spring 96 functions as the second spring (same as 20 in Fig. 2)(higher spring rate). In assembly, the retaining ring 90 is received in the bottom of the outer tube 86, and the guide stop 92 is received on top of the retaining ring 90. A flange portion 98 of the guide stop 92 rests adjacent to the retaining ring 90 and a collar portion 100 extends upwardly into the interior of the outer tube 86. The inner and outer springs 94, 96 are both received on top of the guide stop 92 in nested relation, the inner spring 94 being longer than the outer spring 96 as described in connection with the first embodiment 10. The plunger 88 is received through the center of the inner spring 94 and guided through the collar 100 of the guide stop 92 and then through an aperture in the retaining ring 90. A stirrup interface 102 is connected to the terminal end of the plunger 88 that extends through the retaining ring 90. The stirrup interface 102 provides for connection to the stirrup (not shown). The yoke 84 includes a downwardly depending collar 104 that is outwardly threaded. The threaded portion of the collar 104 is threaded into an inwardly threaded portion of the outer tube 86. As the collar 104 of the yoke 84 is threaded into the outer tube 86, the bottom edge of the collar 104 engages the upper end of the outer spring 96, compressing the outer spring 96 into a pre-loaded state. In this regard, the outer spring 96 is compressed between the bottom edge of the yoke collar 104 and the upper surface of the flange 98 of the guide stop 92. Likewise, the yoke 84 engages with the flange 106 at the upper end of the plunger 88 and urges the plunger 88 downwardly to compress the inner spring 94 into a pre-loaded state where the upper spring 94 is compressed between the lower surface of the flange 106 of the plunger 84 and the upper surface of the flange 98 of the guide stop 92. The yoke 84 further includes a floating pin 108 to provide for connection to the saddle (not shown). In use, the guide stop 92 provides a guide for the plunger 88 to insure proper linear movement of the plunger 88 within the outer tube 86. In addition, the upper edge of the collar 100 of the guide stop 92 provides a stop to limit downward movement of the plunger 88. It can therefore be seen that the rider of a horse can easily use the present stirrup suspension to improve his suspension capability beyond the boundaries of normal physical limitations. The suspension effectively improves rider balance, performance and safety without significant changes to riding style or existing equipment. The stirrup suspension is small and lightweight, and is easily and quickly installed between the saddle stirrup strap leather and the stirrup. In connection with potential design and marketing considerations, it is further contemplated that the stirrup (not shown) could be directly connected to, or integrated with, the plunger 14, thus eliminating the need for the stirrup connector 16 and connector strap 46. Furthermore, the stirrup suspension is designed so that it can be adapted to support the individual requirements of each rider based on body weight, riding style, jump heights, and performance desires. For these reasons, the instant invention is believed to represent a significant advancement in the art which has substantial commercial merit. While there is shown and described herein certain specific structure embodying the invention, it will be manifest to those skilled in the art that various modifications and rearrangements of the parts may be made without departing from the spirit and scope of the underlying inventive concept and that the same is not limited to the particular forms herein shown and described except insofar as indicated by the scope of the appended claims.

Claims: What is claimed is: 1. A stirrup suspension comprising: a tubular housing having a bottom wall and continuous side wall extending upwardly from the bottom wall, said bottom wall having an opening therein, said side wall having an upper peripheral edge; a plunger slidably received within said housing, said slide including a rod having an upper end and a lower end, said upper end including a flange, said lower end extending through said opening in said bottom wall; a first spring element received around said plunger, said first spring element being effective for exerting a force Fi under a minimum load; and a second spring element received around said plunger, said second spring element being effective for exerting a force F 2 that is greater than Fi under said minimum load, said plunger being slidably movable within said housing during riding wherein said flange member compresses said first and second spring elements. 2. The stirrup suspension of claim 1 further comprising a yoke mounted on said upper peripheral edge of said housing. 3. The stirrup suspension of claim 2 wherein said yoke is removable mounted on the upper peripheral edge of said housing. 4. The stirrup suspension of claim 3 wherein said upper peripheral edge of said side wall, and said cap each including corresponding mating formations for removably securing said cap to said upper peripheral edge of said side wall. 5. The stirrup suspension of claim 1 further comprising a stirrup connector coupled to the lower end of said plunger. 6. The stirrup suspension of claim 1 further comprising means for preloading said first and second spring elements in compression. 7. A stirrup suspension comprising: a tubular housing having a bottom wall and continuous side wall extending upwardly from the bottom wall, said bottom wall having an opening therein, said side wall having an upper peripheral edge; a plunger slidably received within said housing, said plunger including a rod having an upper end and a lower end, said upper end including a flange, said lower end extending through said opening in said bottom wall; a stirrup connector mounted to the lower end of said plunger; a first spring element received around said plunger and captured between said bottom wall and said flange of said plunger, said first spring element having a free length L f i and diameter Di, said first spring element being effective for exerting a force Fi under a minimum load; and a second spring element received around said first spring element adjacent to the bottom wall of the housing, said second spring element having a free length L f2 that is less than L f i and diameter D 2 that is greater than Di, said second spring element being effective for exerting a force F 2 that is greater than Fi under said minimum load, said plunger being slidably movable within said housing during riding wherein said flange member compresses said first and second spring elements, said first spring element absorbing downward forces under normal riding conditions, said first and second spring elements cooperating to absorb downward forces under jumping conditions. 8. The stirrup suspension of claim 7 further comprising a yoke mounted on said upper peripheral edge of said housing. 9. The stirrup suspension of claim 8 wherein said yoke is removable mounted on the upper peripheral edge of said housing. 10. The stirrup suspension of claim 9 wherein said upper peripheral edge of said side wall, and said cap each including corresponding mating formations for removably securing said cap to said upper peripheral edge of said side wall. 11. The stirrup suspension of claim 7 wherein said stirrup connector is removably mounted to the lower end of said plunger. 12. The stirrup suspension of claim 7 further comprising means for preloading said first and second spring elements in compression. 13. The stirrup suspension of claim 12 further comprising a yoke threadably mounted on said upper peripheral edge of said housing, said yoke engaging said flange of said slide element and moving said plunger downwardly within said housing to preload said first spring element in compression, said yoke including a downwardly depending collar extending into said housing and engaging an upper end of said second spring element to preload said second spring element into compression. 14. A stirrup suspension comprising: a tubular housing having a bottom wall and continuous side wall extending upwardly from the bottom wall, said bottom wall having an opening therein, said side wall having an upper peripheral edge; a plunger slidably received within said housing, said slide including a rod having an upper end and a lower end, said upper end including a flange, said lower end extending through said opening in said bottom wall; a stirrup connector mounted to the lower end of said plunger; a first spring element received around said plunger said first spring element being effective for exerting a force Fj under a minimum load; and a second spring element received around said plunger, said second spring element being effective for exerting a force F 2 that is greater than Fi under said minimum load, said second spring element being received adjacent to said bottom wall, said first spring element being received on top of said second spring element, said plunger being slidably movable within said housing during riding wherein said flange member compresses said first and second spring elements, said first spring element absorbing downward forces under normal riding conditions, said first and second spring elements cooperating to absorb downward forces under jumping conditions. 15. The stirrup suspension of claim 14 further comprising a yoke mounted on said upper peripheral edge of said housing. 16. The stirrup suspension of claim 15 wherein said yoke is removable mounted on the upper peripheral edge of said housing. 17. The stirrup suspension of claim 16 wherein said upper peripheral edge of said side wall, and said cap each including corresponding mating formations for removably securing said cap to said upper peripheral edge of said side wall. 18. The stirrup suspension of claim 14 wherein said stirrup connector is removably mounted to the lower end of said plunger. 19. The stirrup suspension of claim 14 further comprising means for preloading said first and second spring elements in compression.

Inventors: ZUCCHINI MICHAEL R, ZUCCHINI, MICHAEL, R.
Applicants: MOONRAKER FARM INC, MOONRAKER FARM, INC.
Application year: 2000
Main classification: B68C3
IPC codes: B68C3, F16F1, F16F3