Abstract:
A control system for downhill skis enables effective, continuous control of ski-to-surface resistance, to accommodate changing steepness and other conditions during a downhill ski run. Controllably positionable brake elements are mounted on the skis, centrally between the side edges thereof. Positioning motors are mounted on each ski and are operable to controllably project or retract the brake elements relative to the ski bottoms, continuously or in finite increments, allowing the skier to maintain a safe and comfortable skiing experience over almost any ski slope under a wide variety of ski conditions. The braking elements, preferably blade-like and oriented at right angles to the ski axis, are positioned close to the skier&#39;s feet, allowing the skis to be easily controlled in turns and other maneuvers. A spring-loaded, hinged mounting arrangement allows the mechanisms to momentarily pivot to retracted positions whenever the braking elements engage a rock or other immovable object.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates to speed control arrangements for downhill skis, to enable downhill skiers to better control their speed of descent. In principle, and invention is also applicable to other snow recreational devices that slide over a snow surface, such as snow boards. toboggans and the like. 
       BACKGROUND OF THE INVENTION 
       [0002]    In downhill skiing, speed of descent can be controlled in a variety of ways, depending upon factors such as steepness of the slope, snow conditions, irregularities in the terrain, skill and strength of the skier, etc. A skilled skier can check speed by executing a series of turns in relatively rapid succession while maintaining a generally downward trajectory. A less skilled person may tend to ski laterally back and forth across the slope, minimizing the vertical component of the path and executing less frequent turns. Regardless of the level of skill of the skier, however, the condition of a particular area of terrain, unsatisfactory weather conditions, reduced visibility toward the end of the day and/or fatigue can make it difficult at times for a skier to maintain speed at a safe and comfortable level and/or to respond to an emergency condition or obstacle. 
         [0003]    It has been proposed heretofore to provide downhill skis with devices for projecting one or more elements into the snow surface over which the skis are moving, in order to add resistance and reduce the speed of the skis. In the Smith U.S. Pat. No. 4,152,007, for example, brake elements are pivotally mounted at the trailing ends of the skis and are actuated by hydraulic cylinders mounted on the skis. A hand-operated hydraulic pump is mounted on a ski pole and can be operated by the skier who desires to reduce speed. The brake elements are pivoted downward by their respective cylinders and dig into the snow behind the skis to introduce resistance and reduce the speed of the skis. The Daniel U.S. Pat. No. 5,509,683 also has brake elements pivoted at the trailing ends of the skis. The brake elements of Daniel are actuated by electric motors driving linear screw shafts in much the same manner as the hydraulic cylinders of the above-mentioned Smith patent. The Rassman U.S. Publication 2009/0200772 discloses a device with pivoted braking elements, mounted either at the trailing ends of the skis or, if forward of the trailing ends, in straddling relation to the individual skis. In one embodiment of the Rassman device, the braking elements are actuated by a flexible cable connected to grips on the ski poles and operated somewhat in the manner of standard bicycle brakes. In another embodiment, the cables are operated by electric motors on the individual skis, operated by a wireless control carried by the skier. 
         [0004]    The known devices have several significant shortcomings. For example, devices that are attached to the trailing ends of the skis can change the desired balance of the skis by adding extra weight at the trailing end extremities. Moreover, when the trailing end devices are actuated, they can make steering of the skis difficult by tending to hold the ski tails on a pre-existing path instead of allowing them to freely move laterally to enable the skier to change the direction of the skis. When seeking to reduce speed or to stop, the ability to change the direction of the skis relative to the fall line of the hill can be very important. 
         [0005]    In some embodiments of the Rassman et al publication, while the braking elements are mounted forward of the ski tails, a pair of braking elements is arranged to straddle each of the skis. This increases the likelihood of the two skis becoming engaged during skiing to interfere with the skier&#39;s control and also provides exposed sharp edges that could result in injury in a fall. 
       SUMMARY OF THE INVENTION 
       [0006]    The present invention relates to a new and improved control system which provides a downhill skier with a high level of control against excessive speeds, enabling the skier to impose and release variable levels of speed control as he or she descends over different types of terrain on the ski slope. The skier is thus enabled to “downshift” appropriately when starting into a steep or otherwise difficult section of the hill, in order to keep speed at a comfortable level in relation to the skill level of the skier and/or such factors as snow conditions, fatigue, visibility, etc., and to resume greater or full speed as conditions permit. Thus, in a typical descent, a skier may engage and release speed control on a repetitive basis as he or she encounters and traverses areas of increasing and moderating difficulty, enabling the skier to ski under full control at all times. The procedure is not unlike touching and releasing the brakes of an automobile to maintain speed under proper control for the driving conditions. 
         [0007]    In accordance with one aspect of the invention, the control system includes a controllably projectable and retractable braking element which extends downward through each ski, between the side edges thereof, and can be projected variable distances from the bottom of the ski, as necessary or desirable in order to control the level of resistance of the ski to movement over the snow surface. A controllable positioning motor is mounted on top of each ski, directly above the braking element. Preferably the braking element is located as close as practicable to the heel of the ski binding. Normally, the braking elements are maintained in fully retracted positions, with their lower end surfaces substantially flush with the bottom surfaces of the skis. In their retracted positions, the braking elements have no significant effect on the slideability of the skis, and the skier can ski as fast as he or she feels comfortable and under control. When the skier feels a need or desire for some speed-controlling resistance, the positioning motors are actuated to project the braking elements downward, below the bottom surfaces of the skis. The braking elements can be projected incrementally, under the control of the skier, until a comfortable speed level is established. With experience, a skier is able to make an anticipatory “downshifting” adjustment upon starting into a steep, icy or otherwise difficult section of the ski slope, and thus can proactively avoid even short periods of excessive speed for the conditions. 
         [0008]    In an advantageous embodiment of the invention, the control system includes provisions for a plurality of finite positions of increasing projection of the braking elements below the bottom surfaces of the skis, such that the skier can add resistance incrementally, either to reduce current speed or in anticipation of conditions that might otherwise result in excessive speed for the circumstances. This allows the skier to enjoy a more satisfying skiing experience, with the ability to ski up to the maximum level that personal skills and slope conditions permit, without fear of losing control if the skier is confronted with something unexpected. The invention also enables a skier to maintain his or her skis oriented more toward the fall line of the hill while maintaining speed and control, providing a more enjoyable skiing experience and perhaps also contributing to the skiers overall skiing skills. 
         [0009]    To advantage, the braking elements of the new device are mounted at a position spaced well forward of the trailing ends of the skis and preferably as close as practicable to the feet of the skier. The surface engaging elements are thus positioned close to a center of downward force derived from the weight of the skier and also in an area where the snow has been compacted by the weight of the skier on the moving skis, providing increased resistance to a projected braking blade. This is also a region of maximum strength of the skis, allowing the skis to be provided with through openings to receive the braking elements and their supporting structure. The arrangement of the invention also enables the necessary mechanisms to be located entirely between the edges of the skis, such that the braking elements are a minimal impediment to the ability of the skier to make turns and otherwise maneuver in a normal manner, maintaining the skis in a closely spaced, parallel arrangement. 
         [0010]    In a particularly preferred form of the invention, the braking elements are relatively flat, stiff blades, which are disposed transversely to the principal axis of the ski. When the blades are projected incrementally from the bottom of the ski, they present relatively broad surfaces to the snow, to impart resistance to forward movement, while presenting minimal surface area laterally, to minimize resistance to lateral movements of the skis. Minimizing lateral resistance is of particular significance as it minimizes interference with the ability of the skier to make turns as necessary or desirable, even while the braking elements are projected for braking effect. 
         [0011]    In a preferred embodiment of the invention, each of the braking element blades is operably connected to a positioning motor mounted on the upper surface of the ski. A threaded connection between the positioning motor and the braking element enables the braking element to be controllably projected and retracted in accordance with rotations of its positioning motor. Advantageously, the positioning motors are stepper motor linear actuators whose rotations can be precisely incrementally controlled by the skier during continued skiing. 
         [0012]    Because skiers can accidentally run their skis over relatively non-movable objects, such as rocks, tree roots and the like it is desirable to provide shock relief for occasions in which the skier encounters such non-movable objects while the surface-engaging elements are in partially or fully projected positions. To this end, in a particularly preferred embodiment of the invention the positioning motors and blades are pivotally mounted on the skis and spring-urged into their normal operating positions in which the blades are oriented for desired braking effect when projected downward from the ski. However, should a projected blade engage a rock, root or other immovable object, the motor and blade can pivot upwardly momentarily to allow the blade to pass over the object without damaging the mechanism or causing the skier to fall. 
         [0013]    Normally, the positioning motors are driven by associated battery sources housed on each ski. Desirably, the batteries are rechargeable, with the capacity to easily handle a full day of skiing and be recharged overnight. However, should the skier be confronted with exhausted batteries during the course of the skiing day, provisions are made for easy manual operation of the braking elements, if necessary, to enable a skier to continue skiing. 
         [0014]    In one preferred embodiment of the invention a wireless control sender is provided in one ski pole and includes a manually engageable, trigger type control element. Each of the positioning motors is associated with a wireless receiver which receives signals from the sender unit and responds accordingly, instantaneously and synchronously, to re-position the braking element as directed by the sender. Advantageous circuit arrangements are provided, by which each actuation by the skier for added resistance results in a predetermined incremental projection of the braking elements. Retraction of the braking elements can also be controlled incrementally. However, preferentially, the skier can press and hold the sender control for a short interval (e.g., 2 seconds) to first fully retract the braking elements and thereafter re-set them, if indicated, for a desired level of speed control. 
         [0015]    An additional and rather significant advantage of the new system is that, when it is necessary for the skier to walk up an incline without removing the skis, the braking elements may be projected below the ski bottoms, to provide traction for ascending the incline. Normally, in order to walk upward on an incline, a skier must either use an awkward herringbone walking procedure, in which the skis are splayed outwardly at a sufficient angle to minimize the tendency for the skis to slide back down the hill. Alternatively (and/or in addition), substantial backward pressure can be applied to the ski poles to minimize or prevent backsliding. The skier can also turn both skis sideways to the hill and sidestep up the incline. Any of the foregoing procedures are awkward and slow, and require considerable strength and energy. Moreover, skiers sometimes will fall, occasionally resulting in a release of the ski binding which necessitates an awkward and sometimes difficult reengagement of the ski binding on a sloping surface. With the system of the invention, by projecting the braking blades below the ski bottoms, a skier can simply walk the skis directly up the incline, allowing the blades to dig into the snow with each step to prevent one ski from sliding backward while the other is being advanced by the skier. 
         [0016]    For a more complete understanding of the above and other features and advantages of the invention, reference should be made to the following detailed description of a preferred embodiment thereof and to the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]      FIG. 1  is a fragmentary orthographic view of a ski incorporating the ski brake system of the invention. 
           [0018]      FIG. 2  is a top plan view of the ski brake system of  FIG. 1 . 
           [0019]      FIG. 3  is a side elevational view of the ski brake system of  FIG. 1 , showing the braking element in an extended position. 
           [0020]      FIG. 4  is a side elevational view, similar to  FIG. 3 , with parts broken away to illustrate certain details and with the braking element shown in a retracted position. 
           [0021]      FIG. 5  is a back elevational view of the ski brake system of  FIG. 1 , with the braking element shown in an extended position. 
           [0022]      FIG. 6  is a view similar to  FIG. 4 , but partially in cross-section and showing the brake mechanism in a tilted orientation. 
           [0023]      FIG. 7  is an orthographic view, from above, of a base member forming part of the brake system of  FIG. 1  and used for mounting the brake mechanism on a ski. 
           [0024]      FIG. 8  is an orthographic view, from below, of the base member shown in  FIG. 7 . 
           [0025]      FIG. 9  is a longitudinal cross-sectional view along a centerline of the base member of  FIG. 7 . 
           [0026]      FIG. 10  is in orthographic view, from below and in front, of a motor housing forming part of the ski brake system of the invention. 
           [0027]      FIG. 11  is an orthographic view, from below and behind, of the motor housing of  FIG. 10 . 
           [0028]      FIG. 12  is a longitudinal cross-sectional view of the motor housing of  FIG. 10 . 
           [0029]      FIG. 12   a  is an enlarged, fragmentary cross-sectional view of a portion of  FIG. 12 , showing details thereof. 
           [0030]      FIG. 13  is an orthographic view, from above and behind, of the motor housing of  FIG. 10 . 
           [0031]      FIG. 14  is a cross-sectional view taken generally on line  14 - 14  of  FIG. 12 . 
           [0032]      FIG. 15  is a back elevational view of a braking blade element utilized in the ski brake system of the invention. 
           [0033]      FIG. 16  is a top plan view of the blade element of  FIG. 15 . 
           [0034]      FIG. 17  is a side elevational view of the blade element of  FIG. 15 . 
           [0035]      FIG. 18  is an orthographic showing the underside of a cover member used in association with the motor housing of  FIG. 10 . 
           [0036]      FIG. 19  is a central cross-sectional view showing the cover member of  FIG. 18  assembled with a rotatable element for manually operating the braking system, if necessary. 
           [0037]      FIG. 20  is a schematic diagram of a control transmitting system incorporated into a ski pole and operable by a skier for actuating the braking system of the invention 
           [0038]      FIG. 21  is a schematic diagram of a control receiving system mounted on the skis for receiving signals from the transmitting system and actuating the braking systems in accordance therewith. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0039]    Referring to the drawings, the reference numeral  30  designates a typical ski on which is mounted a boot binding, indicated schematically at  31 . Closely adjacent to and behind the boot binding  31  is the braking system of the invention, designated generally by the reference numeral  32 . The braking system  32  comprises a motor unit  33  and a battery box  34 , which also houses electronic controls for the motor unit  33 . The motor unit  33  comprises a base member  35  (see  FIGS. 7-9 ), which includes a mounting flange  36  and a downwardly projecting cylindrical portion  37 . The cylindrical portion  37  has a diameter which is somewhat less than the width of the ski, and is received in a cylindrical through opening  38  provided in the ski ( FIG. 6 ). For example, in a practical embodiment of the invention, the cylindrical projection may have a diameter of about 1.875 inches, for installation on a ski, the width of which, in the region of the boot binding  31 , may be approximately 3.25 inches. The flange  36  has openings  38  to receive fastening screws for securing the base member to the ski  30 . Additionally, both the flange  36  and the cylindrical projection  37  may be adhesively bonded to the ski to provide increased overall strength of the assembly. Locating the unit directly behind the boot binding  31  serves to place the braking unit as close as feasible to the skiers weight, and also places it at a location where the ski tends to have the greatest strength. 
         [0040]    The cylindrical form of the projection  37 , described above, can be advantageous for aftermarket installation of the brake system, because of the relative ease of forming a cylindrical opening in the ski. However, for installations made by original equipment manufacturers (OEM), or where an aftermarket installer has equipment capable of forming non-circular openings in the skis, the projecting portion  37  of the base member  35  may preferably be of rectangular or other non-circular configuration. Where the projecting portion  37  is a rectangular shape, for example, the strength of the ski and brake assembly can be optimized, and the design of component parts of the system is somewhat simplified. 
         [0041]    In the illustrated form of the invention, the base member  35  is provided at its forward edge with a pair of spaced apart hinge lugs  39 . A motor housing  40  is connected to the hinge lugs  39  by a hinge pin  41 , which engages the lugs  39  and also a hinge lug  42  at the forward side of the motor housing. The motor housing is thus mounted on the base member for forward-upward tilting motion, as reflected in  FIG. 6 . 
         [0042]    The motor housing  40 , shown in  FIGS. 10-13 , comprises a bottom wall  43 , front and back walls  44 ,  45  and opposite side walls  46 . In the illustrated embodiment, the motor housing is adapted for the reception of a motor  47  of generally square external configuration, and thus the motor housing is formed with a correspondingly configured internal cavity  48  for the reception of such motor. 
         [0043]    A particularly advantageous, but non-limiting, example of a motor unit for use in the system of the invention is a DINGS&#39;-Motion hybrid stepper motor linear actuator. Such a motor is available from Chang Zhou DINGS&#39; Electrical &amp; Mechanical Co., Ltd. of Changzhou Jaingsu, China. The selected motor has an internal rotor element  49  of tubular form, which is provided with a threaded insert engaging a threaded rod  50  forming part of a braking element  51  ( FIGS. 15-17 ) to be further described. The stepwise rotation of the rotor sleeve  49  enables the threaded rod  50  to be controllably retracted (raised) or extended (lowered) rapidly and with precision. 
         [0044]    As reflected in  FIGS. 10-13 , a guide member  52  projects downward from the bottom wall  43  of the motor housing. Preferably, the projecting length of the guide member is such that it&#39;s flat bottom wall  53  is substantially flush with the bottom of the projection  37  of the base member, and thus with the bottom surface of the ski  30 , when the motor housing is in its normal (non-tilted) position, with its bottom wall  43  flush against the top of the base flange  36 . Both the flange portion  36  and projecting portion  37  of the base member are provided with a through opening  54  of a size and shape to closely receive the guide member  52 , when the motor housing is in its normal position. To accommodate for the upward-forward pivoting action of the motor housing  40 , the back surface  55  of the guide member, and the back surface  56  of the through opening  54  are of arcuate form, curved on a radius extending from the axis of the hinge pin  41 . Accordingly, the guide member  52  is of a size and shape to fit snugly within the through opening  54 , with the arcuate surfaces  55 ,  56  in close proximity, while at the same time allowing for the pivoting action of the motor housing, as will be further described. 
         [0045]    In accordance with an aspect of the invention, the braking system includes a blade-like braking element  51  ( FIGS. 15-17 ) including a transversely elongated blade portion  57 , advantageously of rectangular shape as shown in  FIG. 15 , which is attached to the bottom of the threaded rod  50 . The rod  50 , as previously mentioned, is engaged by a threaded insert in the tubular rotor  49  and thus is adapted to be raised and lowered by operations of the motor  47 . In the illustrated embodiment, the blade  57  is vertically oriented and its side edges  58  are formed in a rounded, semi-circular configuration. The bottom surface  59  of the blade is angled slightly (e.g., 10°), such that the forward edge  60  of the blade lies slightly below the back edge thereof. This forms an edge that can dig into an icy or hard-packed surface for better braking action on such surfaces. If desired, the edge  60  may be serrated to further enhance its braking action on icy surfaces. The center portions of the blade are of slightly increased thickness, forming vertical ribs  61 . This enables the diameter of the threaded rod  50  to be somewhat greater than the thickness of the blade, to provide adequate strength. The vertical ribs  61  also cooperate with a corresponding vertical recesses  61   a ,  61   b  formed in the front of the guide member  52  and in the rearwardly facing surface of the through opening  54  to provide support against lateral forces applied to the blade  57  during skiing. 
         [0046]    Although the motor unit  33  and the braking blade  57  are vertically oriented in the illustrated embodiment of the invention, it will be understood that the blade and motor unit can alternatively be installed to be normally tilted at an angle extending downward and rearward. The alternative arrangement is such that, when the blades are projected below the bottom surfaces of the skis there is a component of force pressing downward on the snow surface. 
         [0047]    As shown in  FIG. 10 , the forwardly facing side of the guide member  52  is recessed to a depth to receive approximately ½ the thickness of the blade  57 . In addition, the bottom wall  43  of the motor housing is formed with a downwardly opening recess  62  of a cross-section corresponding closely to that of the blade  58 , such that the upper portion of the blade can be partly received in the recess  62 , when the blade is fully retracted. 
         [0048]    Although in the illustrated and preferred form of the invention the braking element  51  is in the form of a flat blade  57 , it will be understood by those skilled in the art that other forms of projectable elements may be employed, such as, but not limited to, individual rod-like elements arranged in a lateral array. 
         [0049]    In its fully retracted position, the blade element  57  is positioned with its lower, forward edge  60  substantially flush with the bottom surface of the ski  30 , as shown in  FIG. 4 . When the blade is fully extended, it projects a distance (e.g., ⅜″-⅝″) below the bottom surface of the ski, in order to engage the snow surface and impart resistance to forward movement of the ski. As will be further described, the degree of projection of the blade  57  can be precisely incrementally controlled, in order to give the skier continuous variable control of the resistance in order to respond to differing conditions on the ski slope during a typical ski run. 
         [0050]    When the blade  57  is extended during skiing, significant rearward pressure is applied to the blade, as will be understood. The blade is supported against such rearward pressure by the rigid guide element  52 . Even in a fully projected position of the blade, as reflected in  FIG. 6 , there is sufficient overlap between the upper portion of the blade and the lower portion of the guide element to provide the necessary support. Because the rearward pressures on the blade during braking can result in substantial friction between the blade and the guide member  52 , the system of the invention advantageously includes an anti-friction roller  63  ( FIG. 14 ) which is rotatably received in a recess  64  in the guide member and bears against the back surface of the blade  57  in all operative positions thereof. This facilitates repositioning of the braking blade  57 , as desired, during a ski run. 
         [0051]    As will be well understood, in the course of a ski run, when the skier has the blade element  57  fully or partially projected below the bottom of the ski, there is potential for the projected blade to engage a rock, tree root or other fixed object. Accordingly, to avoid damage to the braking unit and/or causing the skier to fall, it is an aspect of the invention that the entire motor housing, including the blade  57  and guide member  52 , can momentarily be pivoted upward by the forward momentum of the skier, such that the blade can be partially or entirely recessed within the opening  54 , as shown in  FIG. 6 . In this respect, the positioning of the brake element  57  in relation to the arc of curvature of the surface  56  of the through opening  54  in the cylindrical projection  37  is such that, even in a fully projected position, the lower edges of the braking element lie on or inside of (i.e., forwardly of) the arc of curvature. This enables the blade to be momentarily retracted into the through opening  54  when the blade encounters a fixed object. 
         [0052]    In the above described alternative embodiment of the invention, in which the motor unit  33  and braking blade  57  are normally disposed at a downward-rearward angle, engagement of a braking blade with a fixed object can be accommodated in part by upward-forward pivoting action of the motor unit and blade and in part by momentary upward displacement of the ski itself. This combination of effects can be advantageous in minimizing sudden forces on the skier that might tend to affect the stability of the skier. In the alternative embodiment, the initial (normal) angle of the blade can be in the range of 30°-45° from the vertical. 
         [0053]    In the illustrated form of the invention, control over the upward tilting of the motor housing is provided by means of a pair of extensible coil springs  65  (see  FIG. 6 ). The lower ends of these springs are secured by means of a threaded pin  66  which is received in openings  67  in anchor lugs  68  extending from the back side of the base flange  36  ( FIG. 7 ). The upper ends of the springs  65  are anchored by a pin  69  which is received in upwardly opening grooves  70 - 72  formed in ribs  73 - 75  extending vertically along the back wall  45  of the motor housing. The springs  65  are quite strong, and are preloaded in a manner that the motor housing is held tightly downward against the base flange  36  during normal skiing and braking conditions. However, should the projected blade  57  encounter a fixed object or other extraordinary resistance, the springs  65  will allow momentary upward tilting of the entire motor housing, along with the guide member  52  and blade  57 . This allows the braking blade to clear the obstruction, after which the motor housing is returned to its normal position, flat against the base flange  36 , and the blade  57  resumes its desired braking action. 
         [0054]    Although extensible coil springs  65  are utilized in the described, exemplary embodiment of the invention, it will be understood that other forms of resilient elements may be employed. For example, a suitable torsion spring arrangement, not shown, can be incorporated into the pivot mounting of the motor housing to perform the same function as the springs  65 . The use of torsion springs may be preferred in many cases, as providing a neater, cleaner structure, less affected by ice and snow. A further alternative is to secure the motor housing by means of an adjustably releasable detent (not shown), which could be easily set to the skill level of the skier. Upon engagement of a rock or the like, the detent would release the motor housing for upward pivoting movement. The skier would thereafter manually return the motor housing to its operative position, as by pressing downward on the motor housing element with a ski pole. 
         [0055]    Power and control is supplied to the motor  47  from the battery box  34 , which contains suitable batteries, preferably of a rechargeable type. The battery box also houses appropriate circuitry for controlling the operation of the motor  47  pursuant to the skier&#39;s control inputs, as will be further described. A flexible conductor cable  76  connects the batteries and circuitry of the battery box to the motor housing, while allowing the necessary tilting movements of the motor housing. 
         [0056]    In the illustrated embodiment, the battery box  34  is provided at its front and with a central connecting lug  77  which is received between the anchor lugs  68  of the base member  35  and is engaged by the spring anchoring pin  66  (see  FIG. 4 ). This arrangement allows some relative pivotal movement between the battery box  34  and the base of the motor housing  40  to accommodate normal flexing of the ski during a ski run. The back portion of the battery box may be secured to the ski by means of a screw  78  ( FIG. 4 ) and/or adhesive means. The screw  78  advantageously is received in an opening  79  which is elongated somewhat in the longitudinal direction of the ski in order to allow for limited sliding motion between the battery box and the ski during flexing movements of the ski. Alternatively, the battery box may be formed integrally with the base member  35  in a manner to accommodate a certain amount of flexing of the integrated structure along with flexing of the ski. 
         [0057]    In view of the rather harsh environment to which ski equipment is exposed, often being in the sustained contact with wet snow, melting snow, ice, etc. it is contemplated that the batteries and circuitry may be fully encapsulated in a suitable plastic material. In the illustrated embodiment of the invention, which assumes an aftermarket installation, a housing of plastic material, constituting the encapsulated battery and circuitry, can be mounted on the upper surface of the ski, behind the boot binding, generally in the same position and in the same manner as the battery box  34 . However, installations that are made by an original equipment manufacturer of the skis can be integrated directly into the ski structure. Thus, for OEM systems, the fully encapsulated battery and circuitry for the control system can be incorporated into the ski structure, preferably in the region of the boot binding, in a location underneath where the skiers boot will be positioned during skiing. 
         [0058]    Is contemplated that the batteries installed in the battery box  34 , or encapsulated in a block of plastic material, will readily accommodate a full day&#39;s skiing before requiring a recharge. Desirably, the battery containment will include a suitable port (not shown) for a plug-in connection of a recharger for overnight recharging of the batteries. Advantageously, an on-off switch and an associated on-off LED indicator light (not shown) can be associated with the recharging port or otherwise provided on the battery containment. 
         [0059]    Is contemplated that, under certain circumstances, the skier may forget or be unable to recharge batteries between skiing sessions, leaving the skier open to the possibility of losing power on the ski slope with the braking blade  57  in a projected position. To this end, the system of the invention includes a simple arrangement to allow the skier to manually retract the braking blade and continue skiing without the braking facility, as well as to manually extend the braking element in anticipation of a difficult descent. In the illustrated arrangement, the motor housing  40  is provided with a cover  80  ( FIG. 18 ) which is received over the top of the motor housing and secured thereto by suitable screws or other means. The top wall  81  of the cover is provided with a through opening  82  in the center and a recess  82   a  surrounding the opening on the inside of the cover. 
         [0060]    A manipulating disk  83 , typically of circular form, is received over a circular boss  84  on the cover for rotation about center of the cover. A shaft  85 , which is integral with or fixed to the disk  83 , extends through the opening  82  in the cover and is engaged on the underside of the cover by means of a spring washer  86 , such that the disc is secured to the cover but can rotate with respect thereto. The lower end of the shaft  85  is formed with axially extending ribs  87  which are received in slots  88  in the upper end of the tubular rotor element  49 , as shown in  FIG. 19 . Near a peripheral edge, the disk  83  is provided with a circular rib  89  by which the disk may be engaged and rotated, enabling manual rotation of the rotor  49 , if necessary, to retract the braking blade  57  and enable skiing to continue in the desired manner. The size of the circular rib  89  is large enough to enable the skier to operate the disk without removing his or her ski gloves. Alternatively, the disk  83  may be provided with a plurality of radially disposed ribs, indicated by the reference numeral  89   a , to allow the skier to engage and rotate the disk for manual adjustments. Of course, it typically will be necessary for the skier to temporarily stop in order to effect manual adjustments. Nevertheless, the arrangement will enable the skier to proceed safely to the bottom of the hill under all circumstances, even in cases of battery failure or other system malfunction. 
         [0061]    In order to limit downward projection of the braking blade  57  during manual operations thereof, as described above, the back side of the blade  57  is provided with a vertically disposed, U-shaped groove  120  extending from its bottom edge to a point near its upper edge (see  FIG. 15 ). A pin or setscrew  121  is received in a threaded opening  122  provided in the lower extremity of the guide member  52  ( FIG. 12   a ). A projecting end of setscrew  121  is received in the groove  120  to stop downward movement of the blade when the setscrew engages the upper and of the groove. This feature functions only during manual adjustment, of course, as the upper and lower limits of blade movement during normal operations are controlled by position sensor  106 , referred to herinafter. 
         [0062]    It is intended that control and operation of the brake system on the ski  32  will be carried out wirelessly by the skier, preferably by means of a control module  91  incorporated into one of the ski poles  90  as illustrated in  FIG. 1 . The control module  91  preferably is built into the handle  92  of the ski pole and is actuated by means of a trigger switch  93 , which is positioned to be engaged by the skier during a ski run and enables continuous control to be effected by actuations of the trigger switch. The control module  91  preferably includes a wireless sending unit, the signals from which are received in a wireless receiving unit contained in the battery box  34  (or within a block of encapsulating material as previously described). Thus, as the skier proceeds downhill, when the need for braking action is indicated, the skier simply actuates the trigger switch  93  one or more times to actuate the motor  47  in step fashion, with each trigger actuation resulting in a predetermined number of rotational steps of the motor, causing the threaded rod  50  to be moved incrementally downward to apply the desired braking action. Desirably, the control module  91  includes an array  94  comprising a plurality of LED elements which are illuminated in a progressive manner so that the skier can ascertain visually the amount by which the braking blade  57  is projected below the ski bottom. 
         [0063]    In a representative but non-limiting example, it may be convenient to provide an array of six LED indicators. These may include a plurality (e.g., 4) of a first color (e.g., green) and two additional indicators of a different color or colors. The latter would be intended to alert the skier that the braking blades were in or near their fully extended positions. 
         [0064]    As heretofore mentioned, is contemplated that the braking features of the invention are not limited to skis and may be incorporated into, for example, snow boards. Although snow boarders typically will not carry ski poles, a hand-held control module can be provided for the snow boarder in, for example, a form similar to the handle portion of a ski pole having the functional features of the described control module  91 . 
         [0065]      FIG. 20  illustrates schematically an advantageous form of the controller  91  utilized in the system of the invention. The trigger switch  93  allows the user to control the level of braking action according various actuating sequences, which may be comprised of, but not limited to, presses of short duration, presses of long duration, double presses occurring with a specified time period, etc. An alternative trigger switch action could also allow the user to control the braking level according to the level of force imparted upon the trigger, although individual trigger actuations are preferable because skier does not have to be concerned about maintaining a constant trigger force during skiing. Particular examples of trigger switches include, but are not limited to, electrical contacts, magnet and reed switches, magnet and hall effect sensors, photoelectric devices, and force transducers. 
         [0066]    The trigger switch  93  is electrically connected to a controller  95 , which interprets the user&#39;s pressing actions upon the trigger switch, to determine the level of braking action desired by the user. Particular examples of controllers include, but are not limited to, microprocessors, microcontrollers, FPGAs (Field Programmable Gate Arrays), ASICs (Application Specific Integrated Circuit) and discrete logic circuits. Such devices can be readily programmed using routine programming procedures known to the skilled artisan. In a preferred system, pressing and holding the trigger switch  93  for a period of, say, 5-6 seconds will activate the controller and make it ready for controlling the ski brakes. 
         [0067]    In the illustrated system, the controller  95  generates a signal stream within which braking information is encoded. This braking information can be comprised of a number of braking actions or tasks, such as increasing the braking level, decreasing the braking level, applying full braking, or disabling any braking. It is well within the ability of the skilled artisan to encode braking information in a signal stream. Desirably, the controller  95  is associated with the LED array  94  to provide visual feedback to the user of the operative braking level. 
         [0068]    A transmitter  96 , electrically connected to the controller  95 , transmits the signal stream. Particular examples of transmitters include, but are not limited to, a RF (Radio Frequency) transmitters, IR (Infrared) transmitters, and ultrasound transmitters. An antenna  97  associated with the transmitter  96  radiates the signal stream. Particular examples of antennas include, but are not limited to, RF (Radio Frequency) antennas, LEDs (Light Emitting Diodes), and sound transducers. Advantageously, the antenna  97  can be in the form of a wire element extending downward in the ski pole  90 . 
         [0069]    Suitable batteries  98 , preferably of a rechargeable type, are associated with the transmitter apparatus to provide power. A charging port  99  provides a means for the user to connect a charging cable to recharge the batteries when necessary. The batteries may be housed in upper portions of the ski pole  90 , including the handle portion  92 . A power circuit  100  regulates the voltage from the batteries for the controller  95  and transmitter  96 . This power circuit can comprise circuits such as, but not limited to, linear voltage regulators and switching voltage regulators. 
         [0070]      FIG. 21  shows schematically an advantageous form of a ski-mounted brake system  32  for controlling the speed of downhill skiing. Each ski  30  is provided with such a system which, in the illustrated and preferred form of the invention, is controlled by a single controller  91  incorporated into one of the ski poles  90 . The controller  91  provides instantaneous, wireless control of the braking system  32  for each ski. Additionally, the wireless control instructions are precisely synchronized in both skis, so that the skier experiences identical braking response on both skis. 
         [0071]    A suitable antenna  102  receives the signal transmitted from the transmitter apparatus  91  of  FIG. 20 . Particular examples of suitable antennas include, but are not limited to, RF (Radio Frequency) antennas, phototransistors, photodiodes, and sound transducers. A receiver  103  receives the signal from the antenna  102  and provides the necessary amplification and discrimination to reproduce the signal stream generated by the transmitting controller  95 . A ski-mounted controller  104  receives the signal stream from the receiver  103  and interprets the information encoded therein to determine the desired braking level demanded by the user. Particular examples of a controller include, but are not limited to, microprocessors, microcontrollers, FPGAs (Field Programmable Gate Arrays), ASICs (Application Specific Integrated Circuits) and discrete logic circuits. Such devices can be readily programmed using routine programming procedures known to the skilled artisan. 
         [0072]    Upon receipt of control signals from the ski pole-mounted controller  91 , each ski-mounted controller  104  instructs an associated motor driver  105  to operate the associated positioning motor  47  in a desired rotational direction for a predetermined number of steps or rotations, or a predetermined time period, in order to achieve the desired braking level. Particular examples of motor drivers include, but are not limited to, transistors, MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors), and IGBTs (Insulated Gate Bipolar Transistors). Particular examples of motors include, but are not limited to, stepper motors, such as the previously described DINGS&#39; linear actuator, DC (Direct Current) brush motors, and DC (Direct Current) brushless motors. 
         [0073]    An position sensor  106  is associated with the motor  47  to communicate the motor position to the controller  104 . The controller can be programmed to stop the motor in an appropriate number of predetermined positions, corresponding to predetermined projections of the blade  57 , to achieve various degrees of braking action. 
         [0074]    Batteries  107 , preferably rechargeable, are associated with the braking system  32  to provide power. A charging port  108  provides a means for the user to connect a charging cable (not shown) to recharge the batteries as necessary. A power circuit  109  regulates the voltage from the batteries for the receiver  103 , controller  104 , and motor driver  105 . This power circuit can comprise circuits such as, but not limited to, linear voltage regulators and switching voltage regulators. 
         [0075]    If desired, a ski boot-activated power switch  110  can be associated with the power circuit  109  to automatically activate the electronic system upon the insertion of the user&#39;s boot into the boot binding  31  of the ski. Particular examples of such power switches include, but are not limited to, electrical contacts, magnet and reed switches, magnet and hall effect sensors, photoelectric devices, and force transducers. The boot-activated power switch  110  can be associated with either the boot itself or the boot binding mechanism. When the user removes the boot from the binding the system will be automatically powered off. 
         [0076]    An optional speed sensor  111  can be used to communicate the speed of the ski to the controller  104  to allow the controller to automatically modulate the braking level to achieve desired speed levels or to prevent excessive speeds during the course of a downhill run. Particular examples of suitable speed sensors include, but are not limited to, electrical contacts, magnet and reed switches, magnet and hall effect sensors, photoelectric devices, and DC (Direct Current) brush motors. The described modulation can be readily implemented using routine closed loop control procedures known to the skilled artisan, much like a typical cruise control of an automobile. 
         [0077]    The system of the invention is particularly advantageous in that it can be easily incorporated into the ski at the ski shop, using simple, readily available tools. In this respect, skis typically are provided to the sellers in a plain form, without boot bindings or other features. These accessories typically are installed by the seller, after being chosen by the purchaser. Nevertheless, the system of the invention can advantageously be included as an OEM installation, in which case the batteries and circuitry that otherwise would be mounted on the surface of the ski can be encapsulated and incorporated directly into the ski structure, preferably in a position to underlie the skiers boots when secured by the boot bindings. 
         [0078]    The new system is functionally superior to known systems, in that it is contained wholly within the width of the ski and the braking blades are located as close as practicable to the feet of the skier. Several important advantages are derived from this arrangement. Among other things, the braking element, being close to the feet of the skier, is maintained in a desired contact with the skiing surface for optimum braking effect. The optimized braking effect is realized in part because the weight of the skier on the ski, directly ahead of the braking element, serves to pack the snow surface somewhat to present greater resistance to the projected blade. Additionally, because the blade is close to the skier&#39;s center of weight on the skis, maximum downward pressure is applied to the blade to maximize the depth of contact of the blades with the underlying snow surface. This central location on the ski also is a region of maximum strength of the ski, such that the ski can accommodate the presence of the braking system without unduly weakening the structure of the ski. 
         [0079]    Importantly, location of the braking mechanisms near the feet of the skier, in conjunction with configuration of the braking element as a transversely disposed, relatively thin blade-like element, facilitates the skier&#39;s ability to slip the skis sideways during turns and for stopping while the blades are projected downward from the ski bottoms for braking action. This allows the skier to maintain optimum control over the orientation of the skis while utilizing the braking system for speed control. The last mentioned feature is significant in that it enables and encourages the skier to utilize the braking feature preemptively throughout a ski run such that the skier may in effect “downshift” when approaching difficult areas of a ski slope without concern that the braking elements will interfere with the ability to control the skis in an otherwise normal manner. The new system, providing instantaneous, synchronized and precisely controlled braking action, makes it easy and convenient for the skier to utilize the braking feature continuously during a ski run while maintaining otherwise substantially normal skiing techniques. 
         [0080]    The braking system of the invention is also unique in providing for substantially instantaneous and momentary release in the event that a projected braking element encounters a rock, tree root or other fixed object. The hinged and resiliently seated motor housing, carrying the projectable braking element, enables the braking element to be momentarily retracted by the forward momentum of the skis and skier. The upward pivoting motion of the motor housing and braking element enables it to clear the object and allow the skis to pass over without a sharp deceleration of the skis or other action that might damage the equipment or cause the skier to fall. Where the motor unit and braking blade are initially disposed at a downward-rearward angle, an optimum balance can be provided between upward pivoting of the blade, and upward displacement of the ski, when a rock or other fixed object is encountered. This enables the skis to pass over the fixed object with minimum effect upon the momentum and balance of skier. 
         [0081]    The new braking system also enables the skier to “walk” the skis up an incline without having to remove the skis or resorting to slow and awkward procedures such as “herringbone” walking and/or sidestepping and/or pushing strongly backward on the ski poles. The new system enables the skier to project the “braking” blades below the bottom surfaces of the skis, so that the blade digs into the snow surface to prevent or significantly minimize backsliding of the skis when the skis are pointed uphill. Walking uphill, on a reasonable incline, is as simple as elevating the back of one ski and sliding it forward while maintaining weight on the opposite ski. The arrangement significantly minimizes the time and energy involved in walking up an incline. 
         [0082]    It should be understood, of course, that the specific forms of the invention herein illustrated and described are intended to be representative only, as many changes may be made therein without departing from the clear teachings of the disclosure. Accordingly, reference should be made to the following appended claims in determining the full scope of the invention.