Abstract:
The present invention pertains to a spring or alternative elastic, resilient, compressible media cassette for a touring-style ski binding, such as used in alpine touring or telemark skiing. The touring ski binding slip differential cassette provides the skier with variety of tuning options to manually adjust binding size, stiffness, and range of motion. Manual adjustment of binding size, stiffness, and range of motion enhances the touring ski binding ease of use, adjustability, and overall capabilities, further progressing the touring ski binding. In addition, the slip differential cassette provides the touring skier with cassette presets that match each skier to a predetermined binding size, stiffness, and range of motion based on skier weight and ability.

Description:
CROSS REFERENCE TO RELATED U.S. PATENT APPLICATIONS 
       [0001]    This application is a non-provisional of, and claims the benefit under 35 U.S.C. §119(e) of the earlier filing date of U.S. Provisional Application Ser. No. 61/623,551, filed on Apr. 12, 2012, which is hereby incorporated by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to the field of “free heel” styles of skiing, including, but not limited to, alpine touring, ski touring, telemark skiing, backcountry skiing, and Nordic or cross-country skiing. In particular, the present invention relates to an improved binding mechanism for enhancing the dynamics and control of the “free heel” motion. 
       BACKGROUND OF THE RELATED ART 
       [0003]    For the purposes of this patent application, “touring-style” means skiing styles, including, but not limited to, alpine touring, ski touring, telemark skiing, backcountry skiing, and Nordic or cross-country skiing, and “touring-style” binding means ski binding equipment for use with ski gear appropriate to any one of these skiing styles. 
         [0004]    Touring-style skiing requires touring-style binding equipment, which permits a “free heel” motion. In touring-style skiing the heel-portion of the ski boot is releasably attached to a touring-style binding, which provides an elastic or semi-elastic connection to the ski, a ski plate, or to a binding toe-piece. The binding toe-piece is fixedly attached to the ski or to a ski plate, which is attached to the ski, and releasably attaches to the toe of the ski boot, allowing the heel of the ski boot to move freely within a specific range of motion. 
         [0005]    In touring-style skiing, the binding connects the toe of the ski boot to the ski, directly or indirectly. When connected indirectly, the toe of the ski boot may be attached via the binding toe-piece to a ski plate, which is attached to the ski. In motion, the skier&#39;s heel describes an arcuate trajectory, between a resting point, atop the ski or on top of a binding heel-piece, and a fully extended position. The skier&#39;s heel moves primarily in the plane intersecting the longitudinal axes of the skis and substantially perpendicular to the plane of the top surface of the ski. 
         [0006]    Appropriate motion of the skier&#39;s heel depends on tolerances of the ski, boot, binding, and the skier&#39;s foot and leg and includes a rotating or pivoting action about an axis defined by the intersection of the boot toe and the binding toe-piece. Thus, the skier&#39;s boot can pivot at the attachment between the binding toe-piece and the toe of the ski boot to provide the skier&#39;s heel with free mobility and thereby enable a striding motion. This allows the skier to stride on flat terrain, to initiate and terminate turns, and to ascend steeply inclined slopes, in combination with climbing skins or crampons, without resorting to side stepping or herringboning. 
         [0007]    Conventional cartridge bindings for touring-style skiing offer a single, limited method of adjustment for controlling binding responsiveness , namely, manually changing out binding cartridges of different stiffness ratings. This method requires the skier to acquire and carry multiple cartridges of differing elastic/compressive stiffness categories. When the skier wants to change binding cartridge stiffness to adjust responsiveness and range of motion of the binding mechanism, the skier must manually disconnect the current cartridge and manually connect a new cartridge. 
         [0008]    Touring-style skiers demand equipment that is light, reliable, and capable of accommodating changing terrain, weather conditions, and individual preference. It is apparent that the current cartridge binding systems have specific adjustment and control disadvantages. Further development of touring-style ski binding capabilities to provide for easier, dynamic adjustment and control is hereby acknowledged as necessary to advance the current art. 
         [0009]    The need for a touring-style ski binding cartridge replacement with the ability to manually and dynamically control binding size, stiffness, and range of motion is accordingly recognized. The present slip differential cassette meets these needs, providing superior binding adaptability and permitting the skier to dynamically adjust and control the response of the binding on the fly to accommodate changing conditions and individual preference. 
       SUMMARY OF THE INVENTION 
       [0010]    The present invention pertains to a slip differential cassette for use in “free heel” touring-style ski binding mechanisms and containing a spring or alternative media, wherein such media comprises an elastic, resilient, compressible or semi-compressible media for energy-capture and -return. The slip differential cassette of the present invention has a toe-end and a heel-end and is configured to connect to a touring-style ski binding and to enable a modifiable binding stiffness, responsiveness, and range of motion. The slip differential cassette may also be configured to implement a plurality of re-programmable presets for binding stiffness, responsiveness, and range of motion. 
         [0011]    The slip differential cassette includes a cassette cylinder having a first end and a second end, a cassette nut or cassette cap connected to the cassette cylinder at the first end, a cassette piston having a piston head and a piston shaft, a slip differential bolt having a central conduit and configured to thread into the second end of the cassette cylinder, and at least one of a spring and alternative media held within the cassette cylinder between the piston head and the slip differential bolt, wherein the cassette piston shaft passes through the at least one of a spring and alternative media and through the central conduit of the slip differential bolt, which is configured to adjust a compression applied to the at least one of a spring and alternative media. 
         [0012]    The slip differential cassette may implement presets for binding responsiveness and ranges of motion, which provide the touring-style skier with predetermined stiffness values according to skier weight, ability, and preference. The slip differential cassette may have one or more default, re-programmable presets where the displacement, or differential slip, of the cassette piston shaft, as energetically restored by the cassette spring and/or alternative media mechanism, is manually modifiable. This provides the touring-style skier with a cassette and binding mechanism adaptable to specific sizes, stiffness, responsiveness, and ranges of motion based on default and re-programmable presets. 
         [0013]    The slip differential cassette may be configured to connect to the binding heel-connector and to the one of a binding heel-piece, ski, ski plate, and binding toe-piece via at least two portions provided by one or more of a latch, tubing, solid-core wire, stranded wire, braided wire, cable, cord, chain, band, or other suitable connection mechanism, wherein the at least two portions are configured to connect to the slip differential cassette, the binding heel-connector, and the one of a binding heel-piece, ski, ski plate, and binding toe-piece via one of threading and a flanged head. 
         [0014]    The slip differential bolt may be equipped with a slip differential adjustment knob, configured to facilitate manual rotation of the slip differential bolt, and a slip differential lock-nut, configured to lock in place the respective positions of the slip differential bolt and the cassette cylinder. The slip differential cassette may further include a preset gauge viewing panel, wherein the preset gauge viewing panel may be configured to implement at least one of a transparent window, ruled graphical measures, and color coded indicators of relative position. 
         [0015]    The preset gauge viewing panel may comprise a transparent window on the side of the cassette cylinder configured to show the interior of the slip differential cassette and permit easy identification of a relative position of the slip differential bolt and a corresponding effective stiffness of the slip differential cassette. At least one of ruled graphical measures and color coded indicators of relative position may be implemented directly on the transparent window of the preset gauge viewing panel. 
         [0016]    Alternatively, at least one of ruled graphical measures and color coded indicators of relative position may be implemented via at least one sliding screen mechanism overlaying the transparent window of the preset gauge viewing panel. Additionally, at least one locking mechanism may be configured to lock in place the at least one sliding screen mechanism and thereby enable re-programming of slip differential cassette presets. 
         [0017]    The preset gauge viewing panel may further comprise a computer display electrically connected to and in communication with an on-board microcomputer, which is in turn electrically connected to and in communication with a power source, one or more microcomputer input buttons, and at least one of pressure, strain, and stress sensors incorporated in the slip differential cassette. The at least one of pressure, strain, and stress sensors are configured to detect forces applied to and by the at least one of a spring and alternative media. 
         [0018]    The microcomputer input buttons may be located next to the preset gauge viewing panel computer display and are configured to electronically input and select specific binding stiffness, responsiveness, and range of motion values. The microcomputer may further include a computer readable medium, which does not comprise solely signals or energy, for saving and selecting information including slip differential cassette stiffness, responsiveness, and range of motion presets as well as real time performance data and other parameters. 
         [0019]    A touring-style ski binding may include a toe-piece connected to the top surface of a ski or ski plate and configured to attach to the toe-portion of a ski boot, a heel-piece connected to the top surface of the ski or ski plate and configured to provide a resting place for the heel-portion of the ski boot, at least one slip differential cassette having a toe-end and a heel-end and configured to enable modifiable binding size, stiffness, responsiveness, and range of motion and to implement a plurality of re-programmable presets for binding stiffness, responsiveness, and range of motion, each slip differential cassette including a cassette cylinder having a first end and a second end, a cassette-nut or cassette-cap connected to the cassette cylinder at the first end, a cassette piston having a piston head and a piston shaft, a slip differential bolt, having a central conduit and configured to thread into the second end of the cassette cylinder, at least one of a spring and alternative media held within the cassette cylinder between the piston head and the slip differential bolt, wherein the cassette piston shaft passes through the at least one of a spring and alternative media and through the central conduit of the slip differential bolt, which is configured to adjust a compression applied to the at least one of a spring and alternative media, a heel-connector connected to the at least one slip differential cassette and configured to attach to the heel-portion of the ski boot, wherein the at least one slip differential cassette is also connected to one of the heel-piece, toe-piece, ski plate, and ski. 
         [0020]    The at least one slip differential cassette may be configured to connect to the heel-connector and to one of the heel-piece, toe-piece, ski plate, and ski via at least two portions provided by one or more of a latch, tubing, solid-core wire, stranded wire, braided wire, cable, cord, chain, band, or other suitable connection mechanism, wherein the at least two portions are configured to connect to the at least one slip differential cassette, the heel-connector, and the one of the heel-piece, toe-piece, ski plate, and ski via one of threading and a flanged head. 
         [0021]    Orientation of the slip differential cassette is invertible with respect to the touring-style ski binding. In certain embodiments, the first end of the cassette cylinder comprises the toe-end of the slip differential cassette and the second end of the cassette cylinder comprises the heel-end of the slip differential cassette. In other embodiments, the first end of the cassette cylinder comprises the heel-end of the slip differential cassette and the second end of the slip differential cylinder comprises the toe-end of the slip differential cassette. 
         [0022]    By providing the touring-style skier the ability to manually control the binding size, stiffness, and range of motion, the present slip differential cassette improves touring-style ski binding capabilities. Specifically, the slip differential cassette improves the ease and capacity for binding adjustment while enhancing ski, boot, and binding control during ascent, descent, and traverse movements to advance the sport of skiing. 
         [0023]    The objectives, features and advantages of the slip differential cassette will be apparent from the following detailed description of the invention, which is to be read in conjunction with the accompanying drawings. The scope of the invention will be pointed out in the claims. The following drawings, in conjunction with the subsequent description, are presented to enable one of ordinary skill in the art to make and use the present invention and to implement the various embodiments of the present invention. 
         [0024]    Various modifications, as well as a variety of uses in different applications, will be readily apparent to those skilled in the art. The general principles, defined herein, may be applied to a wide range of embodiments. Thus, the present invention is not intended to be limited to the embodiments presented, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein. Furthermore, it should be noted that unless explicitly stated otherwise, the figures included herein are illustrated schematically and without any specific scale, as they are provided as qualitative illustrations of the concept of the present invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0025]      FIGS. 1A and 1B  illustrate the individual components of a touring-style ski binding, including the ski, boot and binding components. 
           [0026]      FIG. 2  illustrates the individual elements in the component group of the slip differential cassette shown in  FIGS. 1A and 1B  using a spring as the elastic, compressible media. 
           [0027]      FIGS. 3A ,  3 B, and  3 C illustrate an embodiment of the slip differential cassette in cross-section with the cassette set to one of three default presets; pro (A), expert (B), and tour (C), having a cassette chamber containing a spring as the elastic, resilient, compressible media. 
           [0028]      FIGS. 4A ,  4 B, and  4 C illustrate an embodiment of the slip differential cassette in cross-section with the cassette set to one of three default presets; pro (A), expert (B), and tour (C), having a cassette chamber containing a hydraulic or pneumatic fluid as the elastic compressible media. 
           [0029]      FIG. 5A  demonstrates some of the spring parameters that determine the spring constant.  FIG. 5B  depicts an example of a variable pitch spring. 
           [0030]      FIGS. 6A and 6B  illustrate the individual components of the slip differential cassette stiffness adjustment mechanism, including the slip differential bolt, the slip differential lock-nut, and a cassette cylinder cut-away showing the preset gauge viewing panel. 
           [0031]      FIGS. 7A ,  7 B,  7 C, and  7 D illustrate the slip differential cassette piston shaft, including  3  different cable mount attachment mechanisms. 
           [0032]      FIGS. 8A ,  8 B, and  8 C illustrate the slip differential cassette cylinder, including 3 different cable mount attachment mechanisms applicable to either cassette nut or cassette cap embodiments. 
           [0033]      FIGS. 9A and 9B  illustrate the slip differential cassette, including the lockable sliding screen, overlying the preset gauge viewing panel window, and a screen locking mechanism for locking the sliding screen into place to physically program preset ranges. 
           [0034]      FIG. 10A  illustrates the slip differential cassette cylinder including a microcomputer, shown by a dashed outline behind the preset gauge viewing panel, a pressure sensor, and a battery power source.  FIG. 10B  illustrates the slip differential cassette cylinder including the microcomputer input buttons. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0035]    For the purposes of this description, “touring-style” means skiing styles, including, but not limited to, telemark skiing, alpine touring, backcountry skiing, ski touring, and Nordic or cross-country skiing, and “touring-style binding” means ski binding equipment for use with ski gear appropriate to any one of these skiing styles. 
         [0036]    The disclosed touring-style ski binding, slip differential cassette, and other components will become more thoroughly understood through the claims below and the subsequent detailed description and through elaboration of possible embodiments and configurations. The described embodiments and configurations provide exemplary details of the invention only, which should not in any way be interpreted to limit the invention. 
         [0037]    Description of the present invention makes reference to the embodiments and configurations of the included figures.  FIGS. 1A-10B  illustrate components of the slip differential cassette, or cassette  10  for short, described in the current disclosure. The drawings in the figures are not to scale and are not intended to limit the scope of the invention in any way. 
         [0038]    As shown in  FIGS. 1A and 1B , the slip differential cassette  10  is for use in a touring-style binding  100 , which connects the ski  130  to the ski boot  150  to provide the skier with a “free heel” action. The touring-style ski binding  100  includes at least one slip differential cassette  10 , a toe-piece  110 , a heel-connector  120 , and at least two connecting portions  80  and  90  provided by one or more of a latch, tubing, solid-core wire, stranded wire, braided wire, cable, cord, chain, and band, or other suitable connection mechanisms. Such connecting portions  80  and  90  may be made of metal, alloys, alloy-composites, polycarbonates, synthetic fibers, carbon fibers, fiber reinforced polymer composites including but not limited to carbon fiber reinforced plastics, or other suitable materials. 
         [0039]    The binding  100  may also incorporate a binding heel-piece  140 , which may be fixedly attached to the top surface of the ski  130 , to provide a surface upon which the sole of the heel-portion of the ski boot  150  may rest. The at least two connecting portions  80  and  90  connect the slip differential cassette  10  to the heel-connector  120  and to one of the heel-piece  140 , toe-piece  110 , ski plate  132 , and ski  130 , respectively. The at least two connecting portions  80  and  90  may connect to the heel-connector  120  and to one of either the heel-piece  140 , toe-piece  110 , ski plate  132 , and ski  130  via one of threading, a flanged cable head, or other suitably securable connection mechanism. 
         [0040]    The touring-style binding  100  attaches to the ski boot  150  at the binding heel-connector  120  and at the binding toe-piece  110  and provides an elastic or semi-elastic “free heel” connection between the heel-portion of the ski boot  150  and the ski  130 , ski plate  132 , binding toe-piece  110 , or binding heel-piece  140 . The heel-portion of the ski boot  150  is releasably attached to the touring-style binding  100  at the binding heel-connector  120 . The binding toe-piece  110  releasably attaches to the toe of the ski boot  150  and may be fixedly attached, directly or indirectly, to the top surface of the ski  130 . When attached indirectly, the binding toe-piece  110  may be fixedly attached to a ski plate  132 , which is in turn attached, fixedly or releasably, to the ski. Various embodiments of the touring-style binding  100  may be configured and fabricated to incorporate any binding attachment mechanisms known in the art for securing the binding  100 , cassette  10 , and ski boot  150  to the ski  130 . 
         [0041]    In motion, the skier&#39;s heel describes an arcuate trajectory, between a resting point, atop the ski  130  or ski plate  132 , or on top of a binding heel-piece  140 , and a fully extended position.  FIG. 1A  shows the touring-style ski binding  100  in the resting position with the sole of the heel-portion of the ski boot  150  firmly planted on the top of the binding heel-piece  140 .  FIG. 1B  depicts the touring-style ski binding  100  in the fully extended position with the heel of the ski boot  150  at its furthest position from the heel-piece  140 . 
         [0042]    The slip differential cassette  10  provides an elastic, resilient, energy-capture-and-return mechanism for use with touring-style ski bindings  100  to provide a restorative force capable of replacing the heel of the ski boot  150  from the fully extended position to a position of contact with the top surface of the ski  130 , ski plate  132  or binding heel-piece  140 . The cassette  10  comprises a manually adjustable binding component and provides “free heel” touring-style skiers with a modifiable range of binding size, stiffness, responsiveness, and range of motion, extending the capabilities of conventional “free heel” binding cartridges. In some embodiments, the slip differential cassette  10  may be incorporated into a conventional touring-style ski binding  100  as a replacement for conventional binding cartridges. 
         [0043]      FIG. 2  illustrates components of the slip differential cassette  10  depicted in  FIGS. 1A and 1B .  FIG. 2  shows in further detail potential configurations and physical characteristics of the slip differential cassette  10  components. Components of the slip differential cassette  10  may include a cassette cylinder  60 , a slip differential bolt  42 , a spring and/or alternative elastic, resilient compressible media (air, fluid, oil, etc.)  12 , a cassette piston  14 , having a piston shaft  16  and a piston head  18 , and a cassette nut  22  or cassette cap  24 . The cassette  10  and binding  100  may additionally include other appropriate components including but not limited to lock-nuts, bolts, nuts, washers, gaskets, seals, and cables or other attachment and connection mechanisms well known in the respective arts, which may or may not be described herein or depicted in the Figures. 
         [0044]    The cassette cylinder  60  and other components of the slip differential cassette  10  may be made from any suitable materials. Suitable materials may include but are not limited to ruggedized plastics, polycarbonates, carbon composites, fiber reinforced polymer composites including but not limited to carbon fiber reinforced plastic, and metals, alloys, and alloy-composites that may include but are not limited to aluminum, titanium, steel, and other metallic and non-metallic constituents. 
         [0045]    The slip differential cassette  10  employs an elastic or semi-elastic, compressible or semi-compressible, resilient component, including but not limited to a spring, coil, and/or alternative media  12  including but not limited to pneumatic (air) or hydraulic (oil or other liquid) fluid, or other adjustably resilient energy-capture-and-return mechanism to restore the heel position and provide an adjustable range of motion and amount of free-heel extension experienced by the touring-style skier. Springs or coils  12  may be made from any suitable materials including but not limited to metals, including aluminum, titanium, and steel, alloys, and composites, including but not limited to alloy-composites and fiber reinforced composites, and other high-compressive/high-tensile strength materials. 
         [0046]    As depicted in  FIG. 3A-3C  and  FIG. 4A-4C , the volume internal to the cassette cylinder  60  and contained by the cassette piston shaft  16 , cassette piston head  18 , and the slip differential bolt  42  comprises the cassette chamber  62 . The cassette chamber  62  holds the spring and/or alternative media  12 . When the cassette piston  14  is actuated by the striding motion of a skier, e.g. when a skier lifts the heel of a ski boot  150 , the piston head  18  compresses the spring and/or alternative media  12 , as shown in  FIGS. 3A and 4A . Skier striding motion actuates the cassette piston  14  of the slip differential cassette  10  by applying a compressive force to the spring and/or alternative media  12 , which in turn applies a resilient, restorative force upon the cassette piston head  18  to pull the heel of the ski boot  150  back to the starting position on the surface of the ski  130  or ski plate  132 , or a binding heel-piece  140  attached thereto. 
         [0047]    The slip differential cassette  10  provides the skier with re-programmable default presets and the capability to manually select or adjust presets to modify stiffness, responsiveness, and range of motion. Presets can be based on rider ability (style), preference, weight, and boot type.  FIGS. 3A-3C  and  4 A- 4 C depict various settings for the slip differential cassette  10  stiffness and selected range of motion, including pro (FIGS.  3 A/ 4 A), expert (FIGS.  3 B/ 4 B), and tour (FIGS.  3 C/ 4 C). When the slip differential bolt  42  is advanced, as illustrated in FIGS.  3 A/ 4 A, or retracted, as illustrated in FIGS.  3 C/ 4 C, the spring and/or alternative media  12  is respectively compressed, FIGS.  3 A/ 4 A, or released, FIGS.  3 C/ 4 C, effectively modifying the stiffness and range of motion, i.e. action, of the slip differential cassette  10 . 
         [0048]    The cassette cylinder  60  comprises a hollow open-ended cylinder having a first end  20  and a second end  40 . In standard orientation embodiments, the first end  20  of the cassette cylinder  60  comprises a toe-end and the second end  40  of the cassette cylinder  60  comprises a heel-end, as shown in  FIG. 1A ,  FIG. 1B , and  FIG. 2 . In alternative orientation embodiments, the orientation of the cassette  10  may be inverted such that the first end  20  and second end  40  of the cassette cylinder  60  may be reversed with respect to the configurations of the exemplary embodiments as shown in  FIGS. 1A and 1B  and detailed herein. In such alternative orientation embodiments, not depicted in the Figures, the first end  20  of the cassette cylinder  60  comprises a heel-end and the second end  40  of the cassette cylinder  60  comprises a toe-end, with respect to the ski binding  100  depicted in  FIG. 1A  and  FIG. 1B . 
         [0049]    In alternative embodiments, the cassette cylinder  60  may be doubly open-ended, i.e. open on both the first end  20  and the second end  40 , or it may be singly open-ended, i.e. open only on the second end  40  ( FIG. 2  and  FIGS. 7A-7B ). In either of these alternative embodiments, the slip differential bolt  42  is configured to thread into the cassette cylinder  60  at the open second end of the cylinder  60 . The slip differential bolt  42  controls the magnitude of the displacement or action of the spring and/or alternative media  12  during the skier striding motion. 
         [0050]    In doubly open-ended embodiments, the cassette nut  22  or cassette cap  24  may be releasably attached at the first end  20  of the cassette cylinder  60  via threading, or any other means conventionally known in the art. Alternatively, the cassette nut  22  or cassette cap  24  may be affixedly attached at the first end  20  of the cassette cylinder  60  via epoxy or other high-tensile bonding, adhesive, welding, or any other means conventionally known in the art. In doubly open-ended embodiments, where the cassette nut  22  or cassette cap  24  attaches to the cassette cylinder  60  via threading the exterior surface of the cassette nut  22  or cassette cap  24  or the interior surface of the cassette nut  22  may be equipped to receive a tool interface, including but not limited to a hex wrench or a screwdriver head, such as a Philips head or a flat head. 
         [0051]    In doubly open-ended embodiments having a cassette nut  22 , the cassette nut  22  forms a plug that matches the interior surface  64  of the first end  20  of the cassette cylinder  60 . The first end  20  of the cassette cylinder  60  may be tapered to help contain and protect the components internal to the cassette cylinder  60  from wear and tear due to weather, environmental, and terrain conditions. In embodiments where the first end  20  of the cassette cylinder  60  is tapered, the cassette nut  22  can take the form of a truncated cone, having a roughly trapezoidal cross-section, or the form of a truncated cone atop a cylinder, having a cross section of a trapezoid atop a rectangular base. 
         [0052]    The cassette nut  22  may incorporate a cylindrical portion of male threading  26 , extending from the base of the truncated conical plug, for threading into a corresponding portion of female threading  66  on the interior surface  64  of the cassette cylinder  60 . Alternatively, where the first end  20  of the cassette cylinder  60  is not tapered, the cassette nut  22  may have a wholly cylindrical form-factor, or other appropriate shape. 
         [0053]    The cassette nut  22  is partially enclosed by the boundary of the physical interface between the cassette nut  22  and the cassette cylinder  60  at the first end  20  of the cassette cylinder  60 . In preferred embodiments, the cassette nut  22  forms an airtight or nearly airtight seal, with the interior surface  64  and/or the portion of female threading  66  at the first end  20  of the cassette cylinder  60 . 
         [0054]    Alternatively, instead of having a cassette nut  22  secured to the interior surface  64  of the first end  20  of the cassette cylinder  60 , a cassette cap  24  may be secured to the exterior of the first end  20  of the cassette cylinder  60 , either by threading or other appropriate means. In doubly open-ended embodiments having a cassette cap  24 , the exterior of the first end  20  of the cassette cylinder  60  may be equipped with a portion of male threading  68  and the cassette cap  24  may be equipped with corresponding female threading  28  for respectively receiving the first end  20  of the cassette cylinder  60 . 
         [0055]    In preferred embodiments, the cassette cap  24  forms an airtight or nearly airtight seal with the first end  20  of the cassette cylinder  60 . Additionally, a cassette lock-nut  30  may be included, with female threading  32  to ride along the portion of male threading  68  at the first end  20  of the cassette cylinder  60 , to lock in place the relative positions of the cassette cylinder  60  and the cassette cap  24 . 
         [0056]    As shown in  FIGS. 8A-8C , for singly-open ended embodiments, the cassette cap  24  and the first end  20  of the cassette cylinder  60  may be physically joined to form a single solid piece. In these embodiments, the first end  20  of the cassette cylinder  60  includes a solid portion that forms a cassette cap  24  that is not physically separate from the body of the cassette cylinder  60 . This means that in singly open ended embodiments the first end  20  of the cassette cylinder  60  and the cassette cap  24  are physically integrated and joined together, there being no physical boundary or interface separating the first end  20  of the cassette cylinder  60  and the cassette cap  24  as there is between the interior of the cassette cap  24  and the exterior of the first end  20  of the cassette cylinder  60  in doubly open-ended embodiments. 
         [0057]    The slip differential bolt  42  is equipped with a portion of male threading  44 , which threads into a corresponding portion of female threading  70  formed on the interior surface  64  of the cassette cylinder  60  at the second end  40  of the cassette cylinder  60 . In preferred embodiments, the portion of male threading  44  on the slip differential bolt  42  makes an airtight seal, or nearly airtight seal, with the portion of female threading  70  at the second end  40  of the cassette cylinder  60 . 
         [0058]    As depicted in  FIGS. 3A-3C  and  FIGS. 4A-4C , the portion of male threading  44  is partially enclosed by the cassette cylinder  60  and a slip differential lock-nut  46  equipped with female threading  58  rides along the portion of male threading  44  not enclosed by the cassette cylinder  60 . The slip differential lock-nut  46  functions to lock in place the relative positions of the slip differential bolt  42  and the cassette cylinder  60 . A slip differential adjustment knob  48 , for manually advancing and retracting the slip differential bolt  42  along the portion of female threading  70  within the cassette cylinder  60 , is located at the exterior end of the slip differential bolt  42 , which protrudes from the second end  40  of the cassette cylinder  60 . 
         [0059]    Manually advancing and retracting the slip differential bolt  42 , as shown in  FIGS. 3A-3C  and  4 A- 4 C, adjusts the effective displacement and responsiveness of the spring and/or alternative media  12  and provides the slip differential cassette  10  with the ability to control stiffness, responsiveness, and range of motion. Compressing the cassette spring and/or alternative media  12  increases the binding stiffness and releasing the spring and/or alternative media  12  decreases binding stiffness, while binding responsiveness and range of motion becomes less or more active, respectively. 
         [0060]    The slip differential bolt  42  has a central conduit  50 , which comprises a hollow channel along the central longitudinal axis of the slip differential bolt  42 . The cassette piston shaft  16  passes through and slides along the central conduit  50 , allowing the striding motion of the skier to actuate the cassette piston  14  and to alternately compress and release the spring and/or alternative media  12 . In preferred embodiments, the surface of the central conduit  50  makes an airtight or nearly airtight seal with the surface of the cassette piston shaft  16 . 
         [0061]    The cassette piston shaft  16  extends along the length of the central axis of the cassette cylinder  60  from beyond the exterior end of the slip differential bolt  42  at the slip differential bolt adjustment knob  48 , through the slip differential bolt central conduit  50  and inside the spring and/or alternative media  12 , to the piston head  18 . The head-end, or top surface of the piston head  18  rests against the interior facing surface of the cassette nut  22  or the cassette cap  24 . 
         [0062]    The diameter of the cassette piston shaft  16  increases to form the piston head  18  at the interior end of the piston shaft  16  between the spring and/or alternative media  12  and the interior facing surface of the cassette nut  22  or cassette cap  24 . The cassette piston head  18  can incorporate a beveled edge  19  having an outer circumference congruent with the outer circumference of the piston head  18 , on the piston shaft side of the piston head  18 . The outer circumference of the piston head  18  and beveled edge  19  makes contact with and slides along the interior surface  64  of the cassette cylinder  60 . The inner circumference of the beveled edge  19  accommodates the diameter of the spring and/or alternative media  12  and may precisely and snugly fit around the outer circumference of the spring and/or the alternative media  12 . 
         [0063]    In doubly open-ended embodiments having a cassette nut  22 , the interior surface  64  of the cassette cylinder  60  is smooth between the portion of female threading  66  and the portion of female threading  70 . In doubly open-ended embodiments having a cassette cap  24  or in singly open-ended embodiments, the interior surface of the cassette cylinder  60  is smooth between the interior facing surface of the cassette cap  24  and the portion of female threading  70 . 
         [0064]    The smooth interior surface  64  of the cassette cylinder  60 , in combination with a smooth outer circumference of the cassette piston head  18  and beveled edge  19 , allows the cassette piston head  18  and beveled edge  19  to easily slide back and forth along the cylinder interior surface  64 . The cassette piston head  18  may be composed of a friction reducing material, or alternatively the outer circumference of the cassette piston head  18  may be coated in an appropriate friction reducing material known in the art. Alternatively, the outer circumference of the cassette piston head  18  may incorporate a friction reducing apparatus such as a piston ring and/or piston seal, or even ball bearings. In preferred embodiments the outer circumference of the piston head  18  and beveled edge  19  makes an airtight or nearly airtight seal with the smooth interior surface  64  of the cassette cylinder  60 . 
         [0065]    The outer diameter of the spring  12  is limited only by the interior surface  64  of the cassette cylinder  60  or the inside circumference of the beveled edge  19 , depending on the particular embodiment. The inner diameter of the spring is theoretically limited only by the diameter of the cassette piston shaft  16 . Along with the physical properties of the spring material and average spring coil diameter, spring parameters, as shown in  FIG. 5A , including but not limited to mean coil diameter, spring thickness or gauge of the spring wire, the number of active coils, free length of the spring, and the spacing between each of the individual coils also contribute to the spring constant or rate, compressive resistance, and total potential displacement of the spring  12  and the spring&#39;s corresponding ability to capture potential energy. In certain preferred embodiments, the spring  12  may have a thick gauge for a greater strength and a wide spacing between each of the coils to allow and increased range of compression and resilient adjustment. 
         [0066]    In certain preferred embodiments, the cassette chamber  62  may be loaded with two or more nested cassette springs  12 , one set inside of another. In multiple spring embodiments, the springs may have different parameters and spring constants to produce a graduated or graded, staged stiffness and responsive action of the binding mechanism, upon compression of the springs  12  by the cassette piston head  18 . 
         [0067]    In other preferred embodiments, the cassette chamber  62  may be loaded with at least one variable pitch spring, or a spring  12  that has a variable average distance between the active coils, as shown in  FIG. 5B . Additionally, the cassette chamber  62  may be loaded with at least one spring  12  that has a variable average coil diameter and/or variable average spring gauge/thickness. In additional preferred embodiments, the cassette chamber  62  may be loaded with at least one spring  12  and an alternative media  12 , including but not limited to a hydraulic or pneumatic fluid. 
         [0068]    In embodiments employing alternative media  12 , such as hydraulic or pneumatic fluids, or in cases where the alternative media  12  would be capable of escaping the cassette chamber  62 , the interior of the slip differential cassette  10  may be hermetically sealed, i.e. sealed airtight, or at least sealed to such a degree as to prevent the media  12  from escaping the cassette cylinder  60 . In embodiments employing hydraulic or pneumatic alternative media  12 , the composition of the alternative media  12 , i.e. oil, air, and/or other fluid, determines the stiffness and responsiveness of the slip differential cassette  10 . 
         [0069]    In embodiments employing hydraulic or pneumatic media  12 , multiple cassette chambers  62  may be implemented, as is well known in the respective arts. Each cassette chamber  62  may be separated from the other cassette chambers  62  by valves, gaskets, seals or other appropriate mechanisms known in the art. 
         [0070]    In certain preferred embodiments, the at least two connecting portions  80  and  90  comprise cables. The exterior end of the cassette piston shaft  16 , or the end of the piston shaft  16  opposite the cassette piston head  18 , incorporates a cable mount. At one end, the cable  80  attaches to the piston shaft  16  cable mount via a cable-head  82  and at the other end of the cable  80  to an anchor point  122  located on the heel-connector  120 . 
         [0071]    In certain preferred embodiments the cassette piston shaft  16  comprises a hollow cylinder connected to the piston head  18 . As shown in  FIG. 7A , the inside surface of the cassette piston shaft  16  may be tapered at the cable mount to receive and hold in place a flanged cable-head  82  of the binding cable  80 . In such embodiments, the piston head  18  has a central aperture through which the cable and flanged cable head pass, such that the cable also passes through the tapered cable mount at the exterior end of the piston shaft  16 , but the flanged cable-head  82  does not. 
         [0072]    As shown in  FIGS. 7B and 7C , the inside surface of the cassette piston shaft  16  includes a portion of female threading  56  comprising the cable mount and the cable-head  82  includes a corresponding portion of male threading  86 . As depicted in  FIG. 7B , the cable-head  82  is threaded into the piston shaft  16  from the exterior end. As depicted in  FIG. 7C , the cable and cable-head  82  pass through a central aperture in the cassette piston head  18  and through the cassette piston shaft  16 , such that the cable-head  82  threads into the cable mount at the exterior end of the piston shaft  16 . 
         [0073]    Respectively advancing and retracting the male threading within the female threading adjusts extension of the binding cable  80  and binding heel-connector  120 , and therefore binding size. Similarly to the slip differential bolt lock-nut  46  which rides on the slip differential bolt  42  portion of male threading  44  and the cassette lock-nut  30  which rides on the cassette cylinder  60  portion of male threading  68 , a cable lock-nut may be implemented to lock in place the respective positions of the cable  80  and the cable mount of the cassette piston  14 . 
         [0074]    As shown in  FIG. 7D , in some embodiments the cable mount may comprise a male threaded portion  52  at the exterior end of the piston shaft  16  and the cable-head  82  includes a corresponding female threaded portion  84 . 
         [0075]    In both singly open-ended and doubly open-ended embodiments the cassette nut  22  or cassette cap  24  may incorporate a cable mount designed to attach to the cable  90  and a corresponding cable-head  92 , as shown in  FIGS. 8A-8C . The cable  90  attaches to the cable mount of the cassette nut  22  or cassette cap  24  at the cable-head  92  and at the other end of the cable  90  to an anchor point  134  located on the ski  130 , or on the heel-piece  140 , toe-piece  110 , or other component including but not limited to a ski plate  132 , affixed to the ski  130 . In certain preferred embodiments, the cables  80 ,  90  attach to the anchor points  122 ,  134 , respectively, with a free spinning connection, including but not limited to a flanged cable-head/tapered-aperture connection. 
         [0076]    As depicted in  FIG. 8C , the cable mount may comprise a tapered central aperture  34  for receiving and anchoring a flanged cable-head  92 . With the flanged cable-head  92  anchored in the tapered central aperture  34  of the cable mount, the cable  90  passes through the central aperture  34  of the cassette nut  22  or cassette cap  24  and through the first end  20  of the cassette cylinder  60  to attach to the anchor point  134 . 
         [0077]    The cable-head  92  may include a portion of male threading  94  designed to thread into a portion of female threading  36  comprising the cable mount of the cassette nut  22  or cassette cap  24 . As shown in  FIGS. 8A and 8B , the male threading  94  may thread into the cable mount from the exterior facing surface or from the interior facing surface of the cassette nut  22  or cassette cap  24 . 
         [0078]    In certain preferred embodiments, the cable mount comprises a portion of female threading  36  recessed below the exterior surface of the cassette nut  22  or cassette cap  24 , which does not penetrate all the way through to the interior facing surface of the cassette nut  22  or cassette cap  24 . By having the female threading  36  of the cassette nut  22  or cassette cap  24  cable mount not penetrate all the way through to the interior facing surface of the cassette nut  22  or cassette cap  24 , the airtight nature of the interior of the cassette cylinder  60  and cassette chamber  62  is preserved. 
         [0079]    In preferred embodiments, the slip differential cassette cylinder  60 , the cassette nut  22  or the cassette cap  24 , the cable-head  92 , the central conduit  50  of the slip differential bolt  42 , and the cassette piston shaft  16 , all make an airtight or nearly airtight seal with all other respective components. 
         [0080]    The cable mounts, respectively of the cassette piston shaft  16  and cassette nut  22  or cassette cap  24 , and the cable heads  82 ,  92  may be configured to accommodate any suitable connection mechanism known in the art. Likewise, the connections between the cables  80 ,  90  and the anchor points,  122 ,  134 , respectively, may be configured to accommodate any suitable attachment mechanisms known in the art. 
         [0081]    The cassette piston  14  interfaces with the interior facing surface of the cassette nut  22  or cassette cap  24  at the head-end surface of the piston head  18 . The interior facing surface of the cassette nut  22  or cassette cap  24  may be topologically configured to engagedly interlock with the head-end surface of the piston head  18 . 
         [0082]    For instance, the head-end surface of the cassette piston head  18  may be equipped with split, half-circular, cross-tilted faces  17  for preferential alignment with corresponding split, half-circular, cross-tilted faces  25  provided on the interior facing surface of the cassette nut  22  or cassette cap  24 . Any suitable configuration of engagedly interlocking surfaces can be used in forming the interior facing surface of the cassette nut  22  or cassette cap  24  and the head-end surface of the piston head  18 . 
         [0083]    In certain preferred embodiments, including but not limited to embodiments having the configuration of interlocking split, half-circular, cross-tilted faces,  17  and  25 , the interlocking mechanism will encourage a preferential direction of spin of the cassette piston  14 . Such preferential direction of spin can be configured to operate to maintain the locked positions of the various cable mounts in embodiments where the cables  80  and  90  are respectively fixedly connected to the anchor points  122  and  134 , such that the cables  80  and  90  do not spin freely with respect to the anchor points  122  and  134 . In other words, the preferential spinning of the cassette piston may be configured to tighten the connections between the various cable mounts, cable heads, and other components of the slip differential cassette  10 . 
         [0084]    In certain preferred embodiments the slip differential cassette  10  may be configured to select from among one or more default presets by manually adjusting the slip differential adjustment knob  48  to rotate the slip differential bolt  42  clockwise or counterclockwise, to respectively advance or retract the slip differential bolt  42 . The slip differential bolt  42  may be equipped with a slip differential lock-nut  46 , depicted in  FIGS. 6A and 6B , capable of locking in place the relative positions of the slip differential bolt  42  and the cassette cylinder  60 , corresponding to a particular preset or degree of stiffness desired by the skier. 
         [0085]    The slip differential cassette  10  is engaged by lifting the heel of the ski boot  150 , thereby extending the binding  100 , actuating the cassette piston  14 , and compressing the at least one of a spring and alternative media  12  with the cassette piston head  18 . Binding stiffness, responsiveness and range of motion can be precisely controlled by setting the slip differential bolt  42 , which is capable of being precisely locked to individual skier preferences with the help of a preset gauge viewing panel  170  and the slip differential lock-nut  46 . 
         [0086]    In certain preferred embodiments, presets may be implemented, (re-)programmed, and selected via a preset gauge viewing panel  170 , shown in  FIGS. 2 ,  6 B,  9 A,  9 B,  10 A, and  10 B on the side of the cassette cylinder  60 . The preset gauge viewing panel  170  may be configured to implement at least one of a transparent window, ruled graphical measures, and color coded indicators of relative position. 
         [0087]    When implemented as a transparent window on the side of the cassette cylinder  60 , the preset gauge viewing panel  170  shows the interior of the slip differential cassette  10  and the cassette chamber  62  to allow the skier to easily identify the relative positions of the slip differential bolt  42  and the spring and/or alternative media  12  and the corresponding effective stiffness of the slip differential cassette  10 . To aid in the ability to consistently determine a precise relative position of the slip differential bolt  42 , at least one of ruled graphical measures and color coded indicators of relative position may be implemented directly on the transparent window of the preset gauge viewing panel  170 . 
         [0088]    Ruled graphical measures may include, but are not limited to, linear delineations, logarithmic scale delineations, other exponential scale delineations, and combinations of the various aforementioned delineations. Color coded indicators of relative position may include but are not limited to differentiated color zones configured to indicate specific relative positions of the slip differential bolt  42  and the spring and/or alternative media  12  and corresponding ranges of cassette stiffness, responsiveness, and range of motion. Additionally, the slip differential bolt  42  may also be delineated with ruled markings or color coding indicators of relative position and presets for stiffness and range of motion. 
         [0089]    In alternative preferred embodiments, at least one of ruled graphical measures and color coded indicators of relative position may be implemented via at least one lockable sliding screen mechanism  172 , shown in  FIG. 9B , overlaying the transparent window of the preset gauge viewing panel  170 . The at least one lockable sliding screen  172  may, when locked in a desired position atop the window, allow precise determination of the relative position of the slip differential bolt  42  and the spring and/or alternative media  12 . 
         [0090]    In embodiments that incorporate at least one sliding screen  172 , to (re-)program the presets the skier may slide the at least one sliding screen  172  into a desired position and lock it in place with at least one suitable locking mechanism  174 , including but not limited to a latch or button operated lock. The at least one sliding screen mechanism  172  may be configured to give a tactile clicking sensation as they slide from one setting to the next to provide an objective sense of the position of the at least one sliding screen  172 . 
         [0091]    For embodiments with two or more lockable sliding screens  172  overlaying the transparent window, the sliding screens  172  may overlay each other or may be implemented side by side. The sliding screens  172  may be locked in place by individual respective corresponding locking mechanisms  174  or by one single locking mechanism  174  corresponding to all of the sliding screens  172 . 
         [0092]    In additional alternative preferred embodiments, as depicted in  FIGS. 10A and 10B , the preset gauge viewing panel  170  may further comprise a computer display  190  electrically connected to and in communication with an on-board microcomputer  180 , which is in turn electrically connected to and in communication with a power source  184 , at least one microcomputer input buttons  188 , and at least one of pressure, strain, and stress sensors  182 . Electrical connections  186 , which may be housed inside the wall of the cassette cylinder  60 , between the power source  184 , the onboard microcomputer  180 , the computer display  190 , the at least one microcomputer input buttons  188 , and the at least one of pressure, strain, and stress sensors  182 , may provide each of these components with power and/or data. 
         [0093]    The cassette nut  22 , cassette cap  24 , slip differential bolt  42 , piston head  18 , or other cassette components may incorporate the at least one of pressure, strain, or stress sensors  182 . The at least one of pressure, strain, and stress sensors  182  are configured to detect forces applied to and by the at least one of a spring and alternative media  12 . In certain preferred embodiments the interior facing surface of the cassette nut  22  or cassette cap  24 , the surface that engages the cassette piston head  18 , incorporates the pressure, strain, or stress sensors  182 . The cassette nut  22  or cassette cap  24  may also contain a power source  184 , including but not limited to a battery or fuel cell. 
         [0094]    Microcomputer input buttons  188  may be configured to provide input to the onboard microcomputer  180  and to select precise stiffness, responsiveness, and range of motion values. Microcomputer input buttons  188  may be provided at locations on the slip differential cassette  10  including but not limited to next to the computer display  190 . The computer display  190  may show, for example but not limited to, a graphical representation of the actual relative physical position of the slip differential bolt  42  or the physical position of the slip differential bolt  42  as measured in English, metric, or other units, digital readings of pressure, strain, or stress values, equivalent stiffness values, and/or other slip differential cassette  10  status readings. 
         [0095]    In certain preferred embodiments an onboard microcomputer  180  is housed within the wall of the cassette cylinder  60 . With the aid of the onboard microcomputer  180 , the skier may input presets by adjusting the slip differential cassette to the desired setting and using the input buttons  188  to command the onboard microcomputer  180  to save the setting in a memory  192 . Alternatively, the microcomputer  180  may be instructed to save arbitrary values as preset selections in the memory  192 . 
         [0096]    In embodiments implementing presets through an on-board microcomputer  180 , any number of presets may be preprogrammed and stored in the memory  192  of the microcomputer  180 . The memory  192  may comprise any computer readable medium that does not comprise solely signals or energy and for the purposes of this description the term computer readable medium specifically excludes signals and energy. 
         [0097]    The skier may use the input buttons  188  to select any desired preset stored in the memory  192  or to enter an arbitrary desired preset. The skier may then manually adjust the position of the slip differential bolt  42  until the onboard microcomputer  180  alerts the skier, visually—via the computer display  190 , audibly, tactilely (vibration mode), or otherwise, that the desired preset configuration has been achieved. In alternative preferred embodiments where the slip differential cassette  10  informs the skier via a vibration mode or audible tone that manual adjustment of the slip differential bolt  42  has achieved the precise relative positions of the slip differential bolt  42  and the spring and/or alternative media  12  corresponding to the desired preset, the tactile vibration or audible tone alert may be implemented via piezoelectric transducers included in the cylinder  60 , on the onboard microcomputer  180 , or in the computer display  190  or input buttons  188 . 
         [0098]    The claimed invention may be expressed in alternative arrangements while still maintaining the spirit of its original purpose and fundamental features. The described embodiments explain but do not limit the invention to the selected exemplary embodiments. Details concerning the invention are covered in the appended claims rather than the previous description. Additional information in the claims concerning the present invention are to be realized to the extent of their own capacity. 
         [0099]    Various modifications and variations of the described cassette and its components will be apparent to those skilled in the art without departing from the scope and spirit of the invention. Although the disclosure has been described in connection with specific preferred embodiments, it should be understood that the invention as claimed should not be unduly limited to such specific embodiments. Indeed, those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the invention described herein. Such equivalents are intended to be encompassed by the following claims.