Patent Publication Number: US-5251923-A

Title: Support plate for a safety ski binding

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to ski control apparatus for varying the characteristics of a ski according to the nature of the snow being skied upon, the type of skiing being performed, the nature of the ski and the skill of the skier, to improve the quality of the skiing and safety of the skier. It relates in particular to apparatus which vary the stiffness of the ski according to the foregoing conditions. 
     2. Description of Background and Relevant Information 
     Important conditions affecting downhill skiers are the nature of the snow, the type of skiing to be done, the type of skis and bindings used and the skill of the skier. The snow and the ski run can vary during a day, while the ski and the skier are generally invariable. The snow can range from ice hard snow, to very loose or soft snow, sometimes called powder snow. There are profound differences in skiing turns and speed according to the type of snow being skied upon. One primary characteristic of a ski is its ability to bend or flex as it carries a skier. A ski flexes and counterflexes, and keeps the skier in control as he or she follows the contour of a slope and enables a skier to manipulate the skis as he or she bounds and rebounds down the slope. In racing events, the snow can be ice hard both to increase the skier&#39;s speed and to avoid ruts in the snow. Hard snow may limit the bending of the skis. Turning is mainly accomplished in hard snow by the skier tilting the skis to dig the edges at the bottom of the ski into the snow by shifting his or her weight and body position. On the other hand, the ski can bend a large amount in powder snow. The longitudinal sides of skis are convex arcs, and it is through the use of the side cuts and bending of the ski that the skier turns; the edges of the skis are of much less importance in turning in powder snow. Regular snow, that is snow whose texture and packing is between hard snow and powder snow, presents other problems to the skier. Experience, communications with racers and other skiing experts, and testing, indicate that a ski stiffer underfoot of the ski boot may be preferable in very hard snow conditions while an overall more flexible ski appears to be preferable in soft snow conditions. An intermediate situation is preferable for snow of intermediate softness. It is also known that a ski loosely attached to the skier transfers little energy from the ski to the skier when the ski encounters obstacles, thus resulting in higher speed. A loose attachment also results in loss of ski control in turns; hence it is desirable to have a loosely connected ski when traveling essentially in a straight line for greater speed and a tightly connected ski when making turns for greater control. 
     The vibration characteristics of skis are also believed to be important. Skis have several vibration modes which are exhibited during skiing. High frequency vibrations break the contact between the ski bearing surface and the snow, which improves speed. On very hard snow conditions, the breaking of the contact between running surface and snow does not result in the same level of benefit but the ski still vibrates resulting in audible and perceptible chatter. A reduction in chatter is desirable in these conditions. Thus different requirements in underfoot stiffness and vibration exist depending on snow conditions. The ski designer, faced with the different kinds of snow, the different types of skiing, and variations in skiers and their bindings, can only develop skis which can handle all of these varying characteristics reasonably well but are not optimized for any specific condition. 
     All ski bindings have an effect on ski stiffness underfoot. When a ski bends during skiing, the distance between the toe piece and the heel piece varies since they move relative to each other with the upward curvature of the ski. However, the length of the ski boot sole remains constant. Therefore, there is generally limited movement rearwardly of the heelpiece in a clamp on the ski to keep it in contact with the boot. The force required to move the heel unit back results in a stiffening of the ski section directly under the binding and boot. It is believed that most ski bindings on the market fall into this category. Therefore ski manufacturers take this stiffening action of the binding system into consideration in the design of the ski. The underfoot stiffness of the ski/binding combination is thus optimized for the type of skier and preferred snow conditions the ski was intended for. Different binding systems and separate devices to be used in conjunction with the ski and commercially available bindings have been manufactured to either increase or decrease the underfoot stiffness of the basic binding/ski configuration. Other devices can effect the normal vibration of a ski. Combinations which decrease stiffness underfoot may improve soft snow skiability while deteriorating skiability towards the end of the hard snow spectrum. Combinations which increase stiffness have the opposite effect. 
     In some systems, the binding is constructed to render the ski more flexible. In the ESS v.a.r. device, a boot support plate having a forward portion which is slidable in a channel on the ski, should render the ski more flexible. However, the support plate is fixed with additional fastening means to the ski, and thus is believed to limit its benefit on soft snow. The fixing of the support plate decreases the bending of the ski. 
     The Tyrolia Freeflex system utilizes a flexible plate attached to the top of the ski. The plate is fixed to the ski at the toe of the binding and is held in place about the heel by a slidable clamp fixed on the ski. Both toe and heel binding units are affixed on the boot support plate. When the ski bends, the heel clamp moves closer to the toe unit but the flexible plate is allowed to slide rearwardly reducing the tendency of the heel unit to move towards the toe unit as in a normal binding configuration. The ski is thus allowed to flex more underfoot. The plate is allowed to move in the slidable clamp but is also held to the ski by an additional sliding point between the toe and the heel. This mounting configuration increases sliding friction and thus the overall decrease of ski stiffening is relatively small. Devices of this nature are disclosed in U.S. Pat. No. 3,937,481. 
     Most ski binding manufacturers produce bindings which increase the stiffness of skis. The stiffness of a ski provides a firm edge to drive into the snow for making turns in hard or intermediate snow. In this respect, it is much like an ice skater who drives his or her blade into the ice to make a turn. A flexible blade would detract from the skater making a turn, just as a very soft ski in the section directly below the boot would detract from the skier turning in hard snow. 
     Some expert skiers performing giant slalom or super giant slalom have found that their turning ability is enhanced when they attach to the ski, such as by gluing, a thin plate on top of the ski in the binding area. This added plate increases the distance between the skier&#39;s boot and the edges of the ski, and enhances the leverage which the skier has to drive the edges of the ski into the snow. WIPO Document 83/00039 discloses a device wherein glue and an elastomeric material hold a plate for supporting a toe piece and heel piece to the ski. The elastomeric material absorbs some of the vibration of the ski on the hard snow and relieves some of the discomforting noise of the ski rapidly smacking against the snow. Furthermore, the device stiffens the ski/plate/binding combination in the underfoot area of the ski improving edge control on hard snow. In another device called the Rossi-Bar and disclosed in European Patent Office Publication No. 0409749, a support bar on the ski has stops of elastomeric material at its forward and rearward ends. However, the bar is locked to the ski by clamps along the length of the bar, and it is the clamps and not the rubber stops which prevent the bar from sliding on the ski. Thus, the plate reduces the bending of the ski. In U.S. Pat. No. 3,937,481, a ski binding having an elongated plate is slidably mounted thereon for cushioning the skier when a forward abutment in encountered. Only the forward or toe portion of the system is fixed to the ski, so that the plate allegedly follows the bending of the ski. The device in fact impedes the bending of the ski since it is strapped to the ski in a number of places. A similar device with similar shortcomings is disclosed in Austrian Patent 373,786. A device of this type is sold under the name Derbyflex. It has been believed by many experts that raising the ski binding with such a plate detracts from the skier&#39;s ability to control the ski, since it was thought that the skier had to be close to the snow to &#34;feel&#34; the snow and ski accordingly. The present inventors and other manufacturers believe that this notion is wrong for most types of skiers, and that holding a ski boot somewhat high over the ski increases his or her ability to control the ski. Other patents disclosing ski bindings for increasing stiffness in skis include German Patent 2,135,450 and European Publication 0409749A1. 
     Even though the added plate is beneficial, it only applies to skiing on hard snow where a stiffer underfoot ski is desirable. When used on softer or powder snow, the added stiffness detracts from the skier&#39;s ability to control the ski since easier bending adds to the turnability of the ski in soft snow. 
     Other devices are known having movable boot support plates on skis. For example, U.S. Pat. No.4,974,867 discloses a shock absorbing buffer disposed between a ski and a binding, and is not really related to the stiffness of the binding. 
     The skill of the skier is another condition which the skiing apparatus should take into consideration. Although stiff skis are beneficial to good skiers in events such as giant slalom and super giant slalom, novice skiers should generally use flexible skis for all events, since they enable reasonable performance even though edge control in turns may be sacrificed. 
     The inventors are unaware of any ski bindings or skis which are adaptable to vary the stiffness in the binding location of a ski system according to the nature of the snow or the type of skiing being done. They are aware of no skiing system whose stiffness and vibration characteristics can be changed to perform well in the various skiing conditions. 
     BRIEF DESCRIPTION OF THE INVENTION 
     It is an object of the invention to provide an improved device for controlling snow skis according to the nature of the snow, the skiing to be done, the type of skis and/or the skill of the skier. 
     Another aspect of the invention is to provide a support plate for a ski binding which controls the stiffness of skis in different skiing conditions. 
     Another object is to provide a device for controlling automatically the stiffness of skis in various turning conditions. 
     A further object of the invention is to provide a device for controlling the stiffness of skis incorporating a plate fixable to a ski and having a slidable portion, and an impedance device for controlling the slidable device to obtain the desired stiffness. 
     Another object of the invention is to provide a support plate assembly for controlling the stiffness of a ski with the assembly having a plate attached to the ski and an adjustable stop whose position controls the effects of the plate on the amount of bending of the ski. 
     A more particular object of the invention to provide a support plate and an adjustable stop, the adjustable stop being movable to make the device very stiff such as for hard snow, very loose so that the ski can bend such as for soft snow, and at an intermediate position so that the plate can be free when going straight, and be stiffer underfoot in turns. 
     It is yet another object of the invention to provide improved dampening means for a ski, to approve a skier&#39;s control during the vibration of the ski. 
     It is a further object of the invention to provide a continuously adjustable stiffness device for a ski. 
     It is yet another aspect of the present invention to provide a ski binding for controlling the stiffness of the ski, wherein the support plate and the adjustment means are hydraulic in nature. 
     Another related object of the present invention is to provide a hydraulic support plate assembly which can be modified according to the type of snow on which the ski and binding are to be used, and which provides advantages in both the flexing and counterflexing movement of the ski. 
     It is a general object of the present invention to provide an improved ski control system for use with various types of snow, different degrees of skill of the skier and different skiing events, which system is efficient to manufacture and to use. 
     Other objects will become clear from the description to follow and from the appended claims. 
     One part of the present invention relates to controlling the stiffness of the ski to make the ski more suitable for different types of snow, different skiing events, different skills of the skier, and different types of ski. In fundamental form, this part of the invention includes an engagement member which is fixable at one location, to the ski, and an impedance means which effectively engages the engagement member to change movement of the non-fixed or free portion of the engagement member as bending moments are applied to the ski. 
     In its preferred form, the engagement member could be a support plate which supports a ski boot and runs substantially along the length of a ski boot and is attached to the ski. The plate is fixed to the ski at or near one of its ends. The other end of the plate is a free portion which slides longitudinally relative to the ski as the ski flexes or bends longitudinally about an axis or axes transverse to the longitudinal direction of the ski. In this preferred embodiment, an adjustable stop is provided for selectively engaging the free portion of the plate to limit the relative movement of the plate on the ski. Although the term &#34;stop&#34; is used, it can be any impedance member which directly or indirectly cooperates with the plate to change the movement of the plate relative to the ski. In some versions, the adjustable stop engages the plate, the stop and plate act as an integral unit, and essentially preclude the sliding of the plate, so that the ski cannot bend at the stop and plate. This stiffness adjustment is useful when skiing in turns on hard snow, since the rigid ski can engage the snow as the ski turns through the snow and give the ski a firm and stable condition with respect to the snow. If the adjustable stop is moved away from the plate so that the plate cannot touch the stop, the plate becomes slidable relative to the ski as the ski bends, and is particularly useful in turning in powder snow, where the bending of the ski is important in controlling the ski during such turns. It is also helpful to new skiers who find a flexible ski more stable on all types of snow. The adjustable stop can be moved to an intermediate position so that the plate can engage the stop only during turns where the ski bends beyond a determined amount, at which point the plate and stop become a stiffening member to preclude further bending of the ski at the plate and stop. As the ski unbends or before such bending occurs, there is a space between the stop and the plate so that the plate allows substantial bending of the ski. This can be useful in skiing on regular snow wherein stiffness is only desired during turns. 
     With respect to the foregoing discussion, it is an aspect of a preferred embodiment of the invention that the plate is fixed at its end, so that the other end of the plate is mounted for sliding relative to the ski, such as between lower and upper clamps or guides between which the plate can slide as the ski bends. An adjustable stop is provided near the free end. The adjustable stop can be moved between positions where it engages the plate, is totally disengaged from the ski plate or is at an intermediate position where it can engage or not engage the free end of the ski plate according to the bending of the ski. The stop can be in different forms according to the various embodiments of the invention. It is possible that the plate be fixed in the ski and that the stop be slidable relative to the ski, with the same feature of controlling the stiffness of the ski as described above. 
     According to the preferred embodiment of one aspect of the invention, the support plate includes an elongated main member, and a slide member which can be moved longitudinally on the main member to accommodate ski boots of different sizes. The rear or heel end of the main member is fixed to the ski, and the forward end of the main member has a bearing for the slide. At the forward end of the main member and slide member is an adjustable stop, which in this case is a disc cam. The disc cam is rotatable about an axis which is fixable to the ski. The disc cam has a set of surfaces which can be adjustably juxtapositioned to a forwardly facing surface on the slide member to control the amount in which the slide member and thus the support plate can slide on the ski, to thus control the bending or flexing of the ski. 
     According to another embodiment of the invention, a support plate is fixed at one end to a ski, and has a slidable free end. The adjustable stop is a screw or screw driven member which is mounted in a housing fixed to the ski, and the screw can be adjusted to adjust the spacing between the stop and the plate. 
     In another embodiment, a support plate is fixed to the ski at one end, and has at its opposite end a free portion. The adjustable stop is a transversely movable member which is movable transversely to the ski and has a series of projections towards the free portion of the plate. The location of the transversely movable member determines which projection is opposite the plate, the distance (if any) between the projection and the plate, and the point when stiffness is imparted to the ski. 
     According to another embodiment of the invention, a support plate is fixed at one end to the ski. The impedance means is an adjustable member which includes a follower with a piston movable towards and away from the support plate, and an eccentrically mounted rotatable drive member for moving the follower and piston towards and away from the support plate to adjust the spacing therebetween, and when stiffness is to be imparted to the ski. The drive member can rotate about a horizontal or vertical axis. 
     According to other embodiments of the invention, spring force can be used to vary the stiffness of the ski. The impedance means is an adjustable stop spring biased against the support plate. The amount of compression of the spring determines the additional stiffness imparted to the ski. These spring modes of the invention can be continuously adjustable, rather than the discreet forms of adjustment where the stop only stiffens the ski when it engages the engagement means. 
     According to another embodiment of the invention, a support plate is fixed at one end to the ski and has a sliding free portion. An adjustable stop includes a fixed member opposite the support plate and spaced therefrom, to provide an intermediate stiffening means. In addition, a spring urged member can also engage the support plate to provide a continuously adjustable stiffness as well. One or both of the compression of the spring and the location of the adjustable stop can be adjusted by the skier. 
     The present invention also includes hydraulic embodiments. According to one hydraulic embodiment, a hydraulic cylinder is attached to the ski, to the adjacent free end of the support plate, whose opposite end is fixed to the ski. A piston located within the cylinder has an arm fixed to the free hand of the support plate. Flow valves control the rate of hydraulic fluid flowing as the ski bends and the cylinder moves relative to the piston. The system can be set for flexing or counterflexing. 
     In another related embodiment of the invention, the impedance means can be an adjustable force rocker or stop comprising an inertial pivot arm pivotable about a fulcrum fixable to the ski, the arm having one end attached to spring means while the other end is free. The arm is designed to pivot as a result of the inertial forces acting thereon so that the free end is brought into juxtaposition with the surface of the slide member, to limit the distance which the slide member can slide and thus control the stiffening effect of the support plate during turns when inertial forces bring the arm into juxtaposition with the surface of the slide member. The slide member preferably has a bifurcated forked configuration, and the inertial pivot arm is brough into juxtaposition with the forked end to obtain the stiffening result. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be better understood when reference is had to the following drawings in which like numbers refer to like parts, and in which: 
     FIG. 1 is a schematic drawing of a basic form of the invention, showing an engagement means as a support plate, and an impedance means as an adjustable stop. 
     FIGS. 2 and 3 show two settings of the apparatus shown in FIG. 1. 
     FIG. 4 is a schematic drawing of the apparatus of FIG. 1, but with an adjustable clamp. 
     FIG. 5 is a schematic drawing of a form of the invention where the impedance means includes a progressively variable member as the ski flexes and counterflexes. FIG. 6 is a schematic drawing of a form of the invention, having a screw adjustable stop. 
     FIG. 7 is a schematic drawing of another form of the invention, where the adjustable stop is a transversely movable member. 
     FIG. 8 is a schematic drawing of still another form of the invention, where the adjustable stop includes an eccentric rotatable on a horizontal axis transverse to the ski. 
     FIG. 9 is a schematic drawing of a form of the invention where the adjustable stop includes an eccentric rotatable about an axis vertical to the ski. 
     FIG. 10 is a schematic drawing of a form of the invention where the impedance means is a continuously variable bias device including a friction member. 
     FIG. 11 is a schematic drawing of a form of the invention where the impedance means is a continuously variable device. 
     FIG. 12 is a schematic drawing of a form of the invention where the impedance means includes both a discrete stop device and a continuously variable device. 
     FIGS. 13 and 14 are schematic drawings of the invention where a hydraulic system comprises the impedance means. 
     FIGS. 15A and 15B are exploded isometric views of rearward and forward portions of a support plate assembly of the invention mounted on a portion of a ski, with the cover plate displaced from the assembly to make the components of the assembly more straightforward. 
     FIG. 16 is a plan view of the support assembly of FIG. 15 without a cover plate. 
     FIG. 17 is a cross-section of the support assembly of the invention along the line XVII--XVII of FIG. 16. 
     FIG. 18 is a cross-section of the support assembly along line XVIII--XVIII of FIG. 16. 
     FIG. 19 is a plan view of a further embodiment of the invention, without a cover plate. 
     FIG. 20 is a cross-section of the latter embodiment taken along the longitudinal centerline of FIG. 19. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION 
     The invention is directed to the changing of the stiffness of a ski. It includes an engagement means, which can be a member fixed relative to the impedance means described below (such as being fixed to a ski), and an impedance means which cooperates with the engagement means to change the stiffness of the ski. The engagement means moves relative to the ski as the ski bends, unless this movement is changed, such as by being restricted or stopped by the impedance means. In some forms of the invention, the engagement means is a plate fixed to the ski and the impedance means is a stop for engaging the plate to change--in this case increase--the stiffness of the ski by means of a discrete change such as to stop the articulation between the plate and the stop. In other cases, the engagement means and the impedance means are operatively connected by biasing means or hydraulic means to change--by varying--the stiffness of the ski to modify the articulation between the plate and the stop. The engagement means and the impedance means can be positioned at different places on the ski to control the stiffness at different areas of the ski. However, in its preferred embodiment, the engagement means is a support plate for supporting the ski boot on the ski, and the impedance means is an adjustable stop for engaging the support plate to vary the underfoot stiffness of the ski. The following discussion relates to various schematic drawings of different embodiments, and to a detailed disclosure of one apparatus. 
     A stiffness controlling assembly 101 is shown in FIG. 1. The assembly includes an engagement means which can be a support plate 103, one of whose ends 105 is fixed to the ski 107 as indicated by fastening member 108 and its second end 109 is a free end which can slide in a longitudinal direction of ski 107 within guide means such as a support clamp 111. For the sake of this discussion, end 109 is closest to the forward end of the ski. An impedance means, shown here as an adjustable member, control member or stop 113, can be moved forwards or rearwards to preselected positions as indicated by the arrow 115 within its holding member or clamp 117. As shown, adjustable stop 113 can be moved relative to plate 103 and ski 107, within clamp 117 as indicated by arrow 115. Referring to FIG. 4, a movable clamp 121 can be moved as well with stop 113 held therein for preliminary adjustments, such as by a store or ski shop, to set the stiffness controlling assembly for the type of ski and skill of the skier, as indicated by arrow 119. A space of variable distance between stop 113 and end 109 is designated by the letter S. 
     When assembly 101 is to reduce the bending of the ski, as for example when the ski is to be turned in hard snow, adjustable stop 113 is moved to engage free end 109 of support plate 103, so that S equals 0, as shown in FIG. 2. This renders plate 103 substantially unable to move as bending moments are applied to the ski, and makes the ski stiff beneath plate 103. When the ski is to have its bending unimpaired, stop 113 is moved away from plate 103 as shown in FIG. 1, with S having a relatively high value. Then, regardless of the bending of the ski 107, plate 103 cannot engage stop 113, and no additional stiffness is added to the ski. For an intermediate stiffening condition, as where the skier is making turns on regular snow, S is set to a moderate value as shown in FIG. 3, so that free end 109 only contacts stop 113 during turns when the ski bends sufficiently for the contact to occur, to avoid further bending and improve edge control. The assembly could be arranged so that stop 113 is only set for intermediate stiffness control as shown in FIG. 3, in which holder 117 would not allow the adjustment of stop 113. 
     It should be noted at this time that the foregoing and many of the drawings to follow are schematic in nature, and that S need not be a complete space but could have some substance therein; however, the stiffening feature of the invention will nonetheless apply. Also, the support plate 103 has been shown as an integral member, but it could include a number of members whose effect is as shown for stiffening the ski. Likewise, the adjustable member or stop can have different forms, some of which are shown below. 
     Another form of the invention is illustrated schematically in FIG. 5, showing an embodiment where a substance is included in space S. As in the previous figures, the assembly 151 of FIG. 5 includes a plate 103 held fast at one end to ski 107 by an attachment 108, and its free end 109 is supported for sliding movement in support clamp 111. An adjustable stop 113 is held by a clamp 117. A biasing means such as a coil spring 153 is connected between the end of free end 109 and the end of stop 113 facing it. As free end 109 moves towards stop 113 when ski 107 bends, spring 153 compresses. As spring 153 compresses more with increased bending, the spring forces get progressively greater, resisting the sliding of free end 109. This impedes further bending of the ski. As ski 107 continues to bend, the spring eventually becomes totally compressed, S declines to 0 (S being the distance between the end of free end 109 and the end of the totally compressed spring 153). At this point, assembly 151 is set for turning in hard snow, and plate 103 is unable to slide towards stop 113 and the ski beneath plate 103 is stiff. The counterflexing movement of ski 107 is easier as the ski continues to unbend, since the tension on spring 153 gets progressively less. When the ski is unloaded in this configuration, spring 153 releases its energy against stop 113 and free end 109 of plate 103, causing the ski to counterflex with progressively greater energy and speed. This, in turn, allows the skier to unweigh during counterflex, so that the skiing apparatus rather than the skier absorbs much of the shock as the skier goes down a slope. 
     A schematic of another embodiment 201 of the invention is shown in FIG. 6. Here, a support plate 203 is mounted above a ski 107, with one end, here its rearward end (not shown), fixed to the ski, and its opposite end, which is free and clamped for sliding engagement over the ski by clamps or guides 205. Free end 207 is mounted for engagement with a control member or an adjustable stop 209 which is urged forwardly or backwardly by a screw 211 having threads 213 and a head 215. Screw 211 is mounted in a housing 217. A base plate 219 having thread receiving slots 221 is mounted beneath housing 207 on ski 107. With adjustable stop 209 in engagement with free end 207 of the support plate, the support plate 203 is in a stiff configuration, and cannot bend with the ski but rather restricts the ski from bending beneath assembly 201. In this implementation, the space S between free end 207 and adjustable stop 209 can be adjusted simply by turning screw 211. With S=0 the ski is relatively stiff underneath assembly 201. If S is very large, assembly 201 has essentially no impact on the stiffness of the ski under the assembly. The skier can also adjust S for different relatively small values to stiffen the ski more or less during turns. 
     FIG. 7 shows a transversely movable assembly 301 as part of another embodiment of the invention. Here, a partial top view of the ski 107 includes a support plate 303 which is fixed to the ski at one end, here the rear end, and which is free at its other end 305. End 305 has a narrow portion 307 which ends in a forwardly facing abutment 309. Transversely movable assembly 301 comprises a transversely movable control member 311, a housing 313 including a top wall 315, a base 317, walls 319, 321, and an aperture 327. Member 311 is mounted for movement transverse to ski 107, and has a rearwardly facing protuberance 323 with a rearward abutment face 325 and a peg or handle 329 attached to slide 311 which extends through aperture 327. Surfaces are provided defining a recess 331 which extends partly transverse to the ski and is adjacent protuberance 323. Member 311 can be moved across the ski by sliding peg 329 along aperture 327. Top wall 315 retains member 311 in place. Support walls 321 and 319 extending transverse to the ski are provided for maintaining member 311 in place when member 311 is in either of its positions, i.e., on the upper part of FIG. 7 when recess 331 faces abutment 309, or when (as shown) abutment 325 opposes abutment 309. 
     When the ski is to be placed in its extremely stiff mode, such as when the skier is going to perform giant slalom or superior giant slalom events in hard snow, the skier moves slide 311 so that the slide abutment face 325 engages abutment 309 as shown in FIG. 7. As the ski attempts to bend or flex, support plate 303 is held fast by member 311, giving the ski its stiff underfoot quality, giving the skier more control during his turns on the ski run. On the other hand, when the ski is to be used in softer snow, slide 311 is moved upward so that recess 331 faces abutment surface 309. In this setting plate 203 is free to move forward when the ski flexes and the ski is not stiffened. This embodiment, shown with two positions could be implemented with additional positions and intermediate recesses for obtaining intermediate stiffening conditions. 
     Still another embodiment of the invention is shown in FIG. 8. Here, a support plate 403 is fixed at one end, shown here as its rear end towards the back of ski 107, and has a front end 405. A clamp or guide 407 holds plate 403 for sliding engagement relative to ski 107. A retaining member 409 has a rearwardly extending control arm 411 having a downwardly extending foot 413 whose rearwardly facing face 415 is an abutment or contact 415. The retaining member 409 includes a horizontal cylinder 417 having its axis perpendicular to the axis of the ski. An axis of rotation 419 is offset from the natural rotational axis. Cylinder 417 is rotatable about an axis 419 forward of the center of rotation of the foregoing cylinder by means of a tool such as a screw driver inserted into the head 421 of the eccentric. Rotation of head 421 counterclockwise rotates eccentric 424 counterclockwise, moving the arm 411 forwardly and away from the supporting plate 403. Sufficient movement of arm 411 provides a space between abutment 415 and the free end 405 of support plate 403, providing a space between the two members so that support plate 403 allows limited bending of ski 107. The further forward arm 411 is from support plate 403, the more bending is possible. 
     Referring next to FIG. 9, the device somewhat similar to that shown in FIG. 8 is illustrated. Here, a support plate 503 includes one end which is fixed to the ski (not shown), which here is the rear end of the support plate, and a forward end 505 which is tapered towards its longitudinal axis to form a forwardly extending leg 507 from which two legs 509 extend on opposite sides of a centrally located recess 511. Forwardly of the support plate is disposed an eccentric adjustment or control member 513 having a cylindrical member 515 and with a turning head 517. Eccentric 513 rotates about the central axis of cylinder 515 as head 517 is rotated. Adjustment member or stop 513 includes a follower 519 defining a cylindrical bore in which cylindrical member 515 is concentrically located, and a rearwardly extending leg 521, terminating in a transverse leg 523 having a rearwardly extending abutment face 525. The latter abutment face faces abutment face 527 of support plate 503. The follower has flat surfaces 529 on opposite sides thereof for engagement with opposite, external surfaces 531 of spring 533 extending from a base plate. 
     The stiffness of the apparatus shown in FIG. 9 depends upon the location of adjustment face 525 and the abutment face 527 of support plate 503. In its rearward position, the adjustment member engages face 527 of support plate 503, so that the support plate cannot move relative to the ski, to render the ski stiff. If the eccentric is turned counterclockwise, the follower moves forwardly and creates a space with forward part 509 of the support plate 503. If the space is sufficient so that no amount of bending will cause surface 525 to engage the support plate 503, considerable bending of the ski is possible, and would be particularly useful in powder snow. On the other hand, where the ski is to become stiff only in conditions of hard curves, the eccentric is moved to create a space between abutment surfaces 525 and 527. When there is not sufficient bending of the ski, as in straight skiing down a slope, the support plate allows the ski to bend. However, if there are hard turns made, the rearwardly facing abutment surface 529 engages the forwardly facing abutment surface 527, rendering the ski stiff and inflexible. The rotation of the eccentric thus determines the spacing between the two abutment surfaces and the relative stiffness of the ski. 
     Referring next to FIG. 10, a stiffness controlling assembly 601 is shown including a support plate 603 which is fixed to the ski 107 at one end, here the rear end of the plate, and is free at its opposite end, which shown here is the forward end 605. The free end has tapered portions at the upper and lower part of plate 603 with inclined faces shown at 607 and 609, which run transverse to ski 107. An adjustment, control or retainer member 611 has a housing 612 which is attached to the ski by means of a fastener such as screw 613 and a holding member 615, which is attached to the ski, for receiving retainer or fastening member 613 through a bore 617 contoured to receive the fastener. A spring such as helical spring 619 is disposed in housing 612 and is located to be compressed by compression member such as washer 621 as fastener 613 is rotated. Spring 619 is compressible between shoulder 622 in housing 612 and member 621. 
     Retainer member 611 includes a flange 623 which extends rearwardly, and has an inclined abutment face 625 which is contoured to engage the face 607 of plate 603. Holding member 615 also has a flange 627 extending partly along the length of ski 107, and having an inclined portion with a face 629 contoured to engage the face 609 of plate 603. 
     Screw 613 has a flange 631 which is seated beneath the upper end wall of housing 612 of adjustment member 611, and has a head 633 which can be turned to either move nut 621 into holding member 615 to compress spring 619, or to be urged in the opposite direction to relieve the compression on spring 619. 
     The stiffening in the apparatus shown in FIG. 10 is accomplished by friction rather than by spacing between an adjusting member and a support plate. The apparatus is continuously adjustable. 
     Therefore, in the operation of assembly 601 in FIG. 10, if further stiffening of the ski is desired, screw 613 is tightened to move nut 621 towards the ski to compress spring 619. This compression urges adjusting member 611, and the face of leg 623 against face 625 of plate 603. The tension created by face 607 and face 625, and face 609 and face 629, essentially clamps plate 603 to the ski at its forward end 605, to substantially prevent bending of ski 107 betweem fastener 611 and the anchor between the support plate and the ski. In its most compressed condition, the ski apparatus is extremely stiff underfoot, and is particularly useful in curves made on hard snow. As fastener 613 is loosened, the compression on spring 619 decreases, and the tension on end 605 of support plate 603 becomes less and less. In its least compressed condition, the portion of ski 107 under support plate 603 is essentially bendable, and is particularly useful for skiing on loose or powder snow. There is no need for a clamp to guide support plate 603 along ski 107 as the ski bends, since the forward end of the plate is confined between the retainer 611 and the holding member 615. The friction device 601 has some useful features. First, the spring is a progressive force, the spring force increasing as the support plate between the retainer 611 and the holding member 615, increasing stiffness as the ski bends. Second, the spring provides greater friction for flexing than for counterflexing. However, the friction approaches 0 as the angle α approaches 0. 
     Another continuously adjustable stiffening system is shown in FIG. 11. Here, a support plate 703 is attached to the ski 107 at one end, here the rear end 705, by a clamp or anchor 706, and is slidable at its other end, here the front end 707, in a clamp 709 through which the forward end can slide as the ski bends. A spring 710 is disposed in a housing 711 of a retainer 713. Housing 711, is fixed to ski 107. The housing has a rearward face 715 having a bore through which forward part 707 of plate 703 extends. An enlarged portion 719 urges end 707, and is larger than the bore in face 715 to preclude it from being removed from housing 711. Spring 710 rests against portion 719 and extends forwardly to a shoulder 721 through which a control fastener 723 extends. Fastener 723 extends through housing 711 along a longitudinal axis above ski 107, opposite plate 703. 
     In order to change the stiffness of the skiing apparatus shown in FIG. 11, fastener 723 can be moved to change the compression of spring 710, such as by turning its screwhead 725 with a screwdriver. At its extreme stiffness, fastener 723 is moved to completely compress spring 710. As the fastener is turned to release spring 710, the stiffness of the skiing apparatus beneath plate 703 decreases. Thus, the harder the snow and the more turns being made, the fastener 723 is adjusted to compress spring 710. As the snow gets softer, spring 710 should be decompressed to enable the control of the ski as discussed earlier. 
     A modification of the embodiment shown in FIG. 11 is shown in FIG. 12. Here, a support plate 753 is fixed as described above with respect to FIG. 11, and has a flange 755 attached to forward end 757, with a block 759. A housing 761 holds a spring 763 and control fastener 765, and these all function as corresponding members did in the preceding figure. Housing 761 rests on a support 764 which is fixed to ski 107. A stop 767 extends through support 764 opposite plate 753. A space S&#39; exists between the rearward end of stop 767 and the forward end 757 of plate 753. The stiffness of the ski is continuously adjustable by means of fastener 765 and the compression of spring 763. In addition, the ski also becomes stiff during curves when end 757 of plate 753 contacts stop 767. Stop 767 could be adjustable, and could be moved away from plate 753 so that these members do not contact each other at all, or less frequently, as for example in powder snow. Stop 767 can thus be spaced from plate 753 by an intermediate amount so that end 757 and stop 767 only contact during curves as described previously. Stop 767 could also be adjusted to contact end 757 to allow the skier to stiffen the ski under the assembly to a maximal value. Forward end 757 slides relative to ski 107 through clamps 769. 
     Hydraulic embodiments of the invention are shown in FIGS. 13 and 14. In these figures, support plates 803 are fixed at one end to the ski by anchors 805. The free end 807 is slidable in a clamp 809 attached to ski 107 as the ski bends longitudinally. The free end 807 of plate 803 is attached to a piston 811 slidable in a fluid cylinder 813, which is part of a hydraulic circuit. Cylinder 811 is fixed to ski 107. The part of the cylinder chamber forward of piston 811 is connected by fluid lines to an adjustable valve 815, a selected one of oppositely directed, uni-directional valve heads 816, 817 and a manual fluid valve selector 818 connected to a fluid line for the fluid in cylinder 813 on one chamber or side of piston 811. When the system is set up as shown in FIG. 13, as the ski bends or flexes, forward end 807 and piston 811 move rapidly through the chamber in cylinder 813 since fluid is forced from the cylinder through fast flowing, one way or uni-directional valve head 816, through valve selector 818 and into the side of the cylinder chamber behind piston 811. In this configuration the ski can flex downwardly freely and easily since piston 811 encounters little resistance in its forward movement. When the downward loads which caused the ski to flex are reduced--such as the end of a turn--the ski will tend to return to its normal flex state as fluid flows from the right hand side of cylinder 813, through adjustable valve 815 and into the cylinder on the left hand side of piston 811. The rate of counterflexing will be determined by the adjustment of adjustable valve 815. The counterflex speed of the ski can thus be adjusted by the setting of valve 815, and the counterflex can be dampened. 
     In FIG. 14, valve selector 818 is operatively connected to uni-directional valve head 817. Now when the ski flexes, free end 807 forces piston 811 to the right, and fluid flows through adjustable valve 815; this is generally a slow flow rate depending on how valve 815 is adjusted. During counterflex, the fluid moves very quickly from the left side of piston 811, through one way valve 817 so that the piston returns quickly to the embodiment shown in FIG. 14. This is good for the free and easy counterflexing movement of the ski. 
     FIGS. 15, 15A and 15B are partial exploded isometric views of a support assembly of a preferred embodiment of the invention mounted on a portion of a ski 107. As shown, the support assembly comprises a support plate main member, generally 904, and a support plate slide member, generally 905. The main member 904 and its attached slide member 905, may from time-to-time be referred to as the support plate. The rearward end 903 of the support plate main member 904 is somewhat thicker than the rest of the main member allowing the forward portion of the main member to be spaced from the underlying ski 107. The rearward end of the support plate main member is provided with screw holes 902 for purposes of mounting the main member to the ski and to permit the heel portion of a ski binding to be mounted on the support plate. 
     The support plate main member 904 is connected to the support plate slide member 905, and to the cover plate, generally 906, by means of attachment screws, not shown, which pass through screw holes 911 and which are threaded into threaded bushings 908 attached to slide member 905. 
     As will be seen, the end of the support plate main member 904 opposite the rearward end 903 has a bifurcated, forked configuration with slots 910 in each of the forks and with a slot 933 positioned between the forks extending into the main member. The attachment screws referred to hold the support plate main member 904 securely to the support plate slide member 905, minimizing longitudinal movement between the two. However, in a preferred embodiment of the invention, a ribbed surface is provided at the interface between the two members, and in an especially preferred embodiment, an intermediate layer, for example, an elastomeric material, such as ebonite, is positioned as in intermediate layer between the main member and the slide member. Such a layer not only serves to assure that no longitudinal movement between the two members will occur, but provides an additional advantage in that it tends to dampen vibrations transmitted from the ski to the binding. 
     In the embodiment shown, the support plate slide member 905 is tapered toward the front, culminating in an abutment member 931 which serves to engage a peripheral edge of a control cam disc 920 which serves as an adjustment member or adjustment stop, as will be explained in more detail in the following. The cam disc can be pivoted about a smooth shanked fastener or special purpose screw 909 to juxtapose different peripheral surfaces to abutment member 931 thereby controlling the amount of bending or flexure of the ski, as will also be explained in more detail hereinafter. A head or cam setting lever 930 is employed to position the cam disc as desired, while resilient lugs 924 and 925 are provided to maintain the cam disc in the selected position. 
     A portion of the support assembly, together with the cam disc and other associated structure are positioned between a base plate 913 having lateral edges 914 and 915, and the cover plate 906, which together serve to form a protective housing for parts of the mechanism. The forward ends of the base plate act as a guide for the pivoting movement of the cam disc 920, as will be better seen in FIG. 17. (FIGS. 16-18 are enlarged from that of FIG. 15B for the purpose of clarity). Slot 912 in the cover plate 906 accommodates movement of the forward end of the support plate which occurs during flexure of the ski. 
     While the back end of the support plate, specifically the rearward end of the support plate main member 903, is fixed to the ski and thus immovable, the forward end of the plate, namely, the slide member portion 905, which is supported by a slide bearing yoke, better seen in the other figures, is free to move backward and forward, relative to the surface of the ski, thereby accommodating its flexing. The cam disc 920, in conjunction with abutment member 931 serves to control the degree of permissible movement, thereby providing a means to control the degree of flexure or stiffness which the ski is capable of experiencing. 
     FIG. 16 is a plan view of the support plate of FIG. 15B, however, with the cover plate removed in the interest of clarity. The figure shows the bifurcated forked configuration of support plate main member 904 and its attachment to support plate slide member 905 by means of attachment screws 907 inserted into the threaded bushings 908 extending through forked slots 910, the bushings forming a part of the support plate slide member. Attachment screws 907, which fasten the main member to the slide member, are better seen in FIG. 18. 
     The support plate slide member 905 is retained in slide bearing yoke 918, but is free to move or slide back and forth therein. As stated, the forward part of the slide member tapers to form a projecting abutment member 931 which is juxtaposed to selected peripheral sections of cam disc 920. Depending upon the clearance between the abutment 931 and the peripheral section, the cam disc either prevents, limits, or allows the essentially uncontrolled longitudinal movement of the forward end of the support plate. 
     As illustrated in FIG. 16, the abutment member 931 is juxtaposed to a slightly recessed peripheral section 922 of cam disc 920, thereby allowing some degree of forward movement of the abutment to accommodate flexure or bending of the ski. Should the cam disc be rotated counterclockwise to bring the recessed peripheral section 923 opposite the abutment, substantially unlimited forward travel of the abutment would be possible. However, were the cam disc to be pivoted in a clockwise direction to bring the outer periphery 921 in juxtaposition with abutment 931, essentially no movement of the slide member would be possible, in which case the support plate would act as a stiffening brace for the ski, particularly desirable where a large amount of stiffness is required, for example, during turns on hard snow. The cam disc is moved to its desired position by manipulation of cam setting lever 930. It will be seen that the resilient detents or lugs 924 and 925 engage detent recesses 926 and 927 when the cam disc is in its intermediate position, or, respectively, are located in a position abutting detent projections 928 and 929, locking the cam disc in either its slide member arresting position, or in the position permitting maximum sliding movement. The lateral edges of the base plate are also illustrated in the figure, as is a forward portion 917 of the base plate. While a cam disc with a periphery having distinct &#34;steps&#34; of different radii has been described, it is also possible for the cam disc to have a periphery whose radius varies in a continuous manner. 
     FIG. 17 is a cross-section of a support plate of the invention along line XVII--XVII of FIG. 16. In this figure, the front jaw of the safety ski binding can be seen attached to the cover plate 906 and to the support plate main member and support slide member, 904 and 905 respectively. The figure also shows a ski boot in phantom positioned in the binding. Illustrated in FIG. 17 is the base plate 913 including its front portion 917 and a setback portion 916, which together with the lower portion of the base plate form an opening through which the cam setting lever 930 projects for easy access. A smooth shanked fastener in the form of a screw 909 serves the multiple functions of fastening the base plate to the ski, of serving as a pivot point for the cam disc, and to prevent any lifting or lateral movement of the forward part of the ski binding&#39;s front jaw. As previously indicated, the pivot fastener slot 912 accommodates the back and forth movement of the cover plate, which it will be remembered is attached to the main member and slide members of the support plate during flexure of the ski. 
     Referring again to FIG. 16, a useful feature of the invention, whose function is better seen in FIG. 17, is to be found in the positioning of an elastomeric pad or plate 932 between a portion of the peripheral edge surface of the cam disc 920, and a surface of abutment member 931. As shown, the positioning of the pad can be accomplished by attaching it to the cam disc by pins located on the cam disc, over which the pad is secured by means of holes located in the latter. As is seen particularly clearly in FIG. 17, before the abutment member 931 can make contact with the peripheral edge of the cam disc 920, it must compress the elastomeric pad. The resistance of the pad to such compression exerts a desirable dampening affect which resists flexing of the ski to a degree determined by the resiliency of the pad. The pad may be disposed over one or more of the recessed peripheral sections of the cam disc to obtain the dampening function described. 
     FIG. 18 is a cross-section of the support plate along line XVIII--XVIII of FIG. 16 showing details of the sliding support, which allows the support plate of the invention to accommodate flexure of the ski. 
     FIG. 18 shows the manner in which the support plate slide member 905 is retained by a U-shaped slide bearing yoke 918, the latter being fastenable to a ski by means of fastening screws 919. The support plate main member 904, together with cover plate 906, is fastened to support plate slide member 905 by means of attachment screws 907 which extend into threaded bushings 908 forming a part of the slide member. The lateral edges 914 and 915, respectively, of the base plate enclose the slide bearing yoke 918 and their upper ends are offset inwardly at the top to function as guide rails for the cover plate 906 so that the cover plate, together with the front jaw may slide during ski flexure in relation to the base plate along the longitudinal axis of the ski. As is clear from the figure, the lateral edges of the base plate, in conjunction with the cover plate, form a housing about a portion of the support plate assembly, protecting the parts thereof from damage and dirt which might otherwise be adventitiously introduced. 
     As shown in FIG. 17 and FIG. 18, the attachment screws 907 and 919 are positioned coaxially to each other. This is of considerable advantage since it makes it possible to employ the same drilling template for locating the support plate attachment holes in the ski, as is used for installing the safety ski binding screws. 
     In installing the support plate of the invention, the slide bearing yoke 918 is first screwed to the ski. The support plate slide member 905 is thereafter inserted into the yoke, and the base plate is placed thereon and positioned as desired. Thereafter, the rear end 903 of the support plate main member with the heel part thereon is fastened to the ski. 
     The forked slots 910 in the support plate main member 904, which have the threaded bushings 908 of the slide member 905 fitted therethrough, allow the positioning of main member 904 to slide member 905 to accommodate whatever length of ski boot sole is to be used in the ski binding. In this connection, boot adjustment slot 933 is provided to accommodate the shank portion of fastener 909 in instances where the ski boot sole is extremely short. 
     After placement of the support plate main member 904, the cover plate 906 is placed in position and smooth shank fastener 909 screwed into the ski. The front jaw is then placed on the cover plate in position and attachment screws 907 are screwed into the threaded bushings 908, simultaneously connecting support plate main member 904 to slide member 905, preventing their longitudinal movement relative to each other. 
     With the support plate of the invention installed as described, the cam disc 920 is adjusted to the position desired. In regard to such adjustment, as long as the support plate slide part 905 is free to slide in the slide bearing yoke 918, there will be no stressing of the ski, which will be free to flex or bend in conformity to the terrain over which it is passing. The cover plate 906 and the front jaws participate in such movement since the parts are connected together as indicated. Where the elastomeric pad 932 is present, however, such displacement will occur against the resistance of the pad which functions as a dampening element. 
     An elastomeric pad 934 is attached such as by some appropriate adhesive to slide member 905, to dampen the vibration between member 905 and main member 904 during skiing. Such vibration dampening means can be applied between any horizontally disposed units in the system. 
     FIG. 19 is a plan view of a further embodiment of the support plate of the invention, shown without a cover plate, with like parts to those shown in FIGS. 15-18 having like numerical designators. As illustrated, a support plate main member 904 is fastened to a support plate slide member 935 by means of attachment screws 907, not shown, inserted into threaded bushing 908. The support plate slide member 935 is retained in slide bearing yoke 918, being free to slide therethrough, and is bifurcated at its unattached end having forks 939 and 940 located thereon. The forks are provided with fork abutment surfaces 941 and 942, respectively, adapted for juxtaposition to surface 943 to the free end 944 of pivot arm 937 which serves as an abutment or control member, or abutment stop. The opposite end of the pivot arm is attached to spring 938 whose other end is anchored, for example, to base plate 936, better seen in FIG. 20. 
     In this embodiment, the pivot arm or abutment stop itself cooperates in limiting the amount of longitudinal movement of which the support plate slide member is capable. In this regard, the inertial force acting on the free end 944 of the pivot arm, for instance, when the ski is running on its edge, serves to automatically pivot the arm so that the outermost radial surface 943 of the free end of the pivot arm 937 pivots to a point at which it is juxtaposed to either fork abutment surface 941 or 942, where it acts to restrain their movement. The pivoting motion acts against the force imposed by the weak spring 938; however, when the inertial force is no longer operable, the spring acts to realign the pivot arm along the longitudinal axis of the ski. 
     Advantageously, the juxtaposed surfaces of abutment surfaces 941 and 942, as well as the outermost radial surface 943 of pivot arm 937 having mating curved surfaces which conform to a radial arc whose center is the pivot point of the pivot arm 937. 
     FIG. 20 is a cross-section view of a support plate of the invention along the longitudinal centerline of FIG. 19. The construction of the pivot arm or adjustment stop is much the same as that previously described in connection with FIGS. 15 through 18, the support plate main member 904 being connected to the support plate slide member 935 by means of attachment screws 907, which engage the threaded bushing 908 disposed in the fork slots of the bifurcated end of the support plate main member 904. The slide member 935 is retained in slide bearing yoke 918, which in turn is fastened to a ski by fastening screws 919. The pivot arm 937, pivotable about the smooth shanked fastener 909 which also fastens base plate 936 to the ski, is urged into a longitudinal position, relative to the ski, by weak spring 938 anchored to the base plate 936. The figure illustrates the thickened section of the pivot arm 944, not only adds inertial mass to the arm, but also provides the necessary surface area 943 at its end to efficiently engage the forked abutment surfaces 941 and 942, respectively. 
     The jaws of the binding and cover plate 906 are fastened to the assembly by attachment screws 907, as previously indicated, while the front end of the jaws are prevented from upward and lateral movement by the smooth shanked fastener 909. 
     If desired, provision may be made for moving the pivot arm 937 along the longitudinal axis of the support plate assembly to allow the clearance between surfaces 941 and 942 with surface 943 to be adjusted in a way allowing more or less movement of the support plate slide member 935, thus adjusting the freedom of the ski to flex. 
     As will be appreciated, the support plate slide member is free to slip back and forth through the slide bearing yoke 918 so long as the ski is moving in a direction of the fall line of the slope, a condition in which no stiffening of the ski adjacent to the support plate will occur. On the other hand, when the ski is moved into a turn, a condition in which inertial force acts on the pivot arm 937, the arm will swing out of the intermediate position illustrated in the figure, the surface 943 of its free end thereupon being juxtaposed with one of the abutment surfaces 941 or 942. In this position, the movement of the slide member 935 is restrained, preventing flexing of the ski and allowing short, rapid turns to be accomplished with precision, even on hard snow. 
     Various systems for controlling the stiffness of a ski have been described above. The skier may manually, or perhaps with the ski pole or some other device, adjust the apparatus according to the type of stiffness to be desired. In the last embodiment, this adjustment is made by the apparatus itself. The skier need not have different skiing apparatus for different types of snow or different abilities of the skier, and need not settle for a binding which is appropriate for only one type of skiing or which approximate different types of skiing but cannot adequately control the stiffness precisely for different types of skiing. Now, the skier need only adjust the apparatus for the type of stiffness desired and to participate in the skiing event. The settings can be changed as the skier desires. The invention further includes dampening means for controlling the vibration of the skis. Furthermore, in some embodiments the skier can continuously adjust the stiffness of the ski. The adjustable member could be at places other than at the forward end of the support plate, such as at the rear end, at both ends and/or in the middle. Although many embodiments are given, it should be appreciated that other variations will fall within the scope of the invention. 
     The invention has been described in sufficient detail to enable one skilled in the art to practice the invention, but variations and modifications within the spirit and scope of the invention may occur to those skilled in the art to which the invention pertains.