Patent Publication Number: US-7722509-B2

Title: Handicapped accessible exercise machine

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
   (Not Applicable) 
   This application claims the benefit of U.S. Provisional Application No. 60/941,845 filed Jun. 4, 2007. 

   STATEMENT REGARDING FEDERALLY-SPONSORED RESEARCH AND DEVELOPMENT 
   (Not Applicable) 
   REFERENCE TO AN APPENDIX 
   (Not Applicable) 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention relates generally to exercise equipment and more particularly to a handicapped accessible exercise machine that incorporates a number of features to simplify operation for users having limited mobility and/or dexterity. 
   2. Description of the Related Art 
   The vast majority of weight training machines that are currently available on the market are designed to accommodate users who possess a full or nearly full range of physical mobility and dexterity. Such machines often incorporate features that require a user to perform intricate manual adjustments to attach and adjust various components, or that require users to position and orient their bodies in tight spaces to accommodate the machines&#39; seating and muscle isolation structures (i.e., benches, backrests, support pads, etc). These features make it difficult, and sometimes impossible, for handicapped users having limited mobility and dexterity to effectively use the machines. For example, a wheelchair-bound paraplegic user may not be able to lift himself onto a bench or move into a cramped space behind the chest pad of a traditional weight machine. Similarly, a user having diminished finger dexterity may have a great deal of difficulty operating conventional spring-loaded locking pins of the type commonly used in weight machines for securing the positions of the machine&#39;s adjustable components. 
   Due to the spatial requirements of a wheelchair and the limited mobility of a wheelchair&#39;s occupant, most weight training machines that are designed for wheelchair-bound users feature highly specialized structures and configurations. The components of such machines must be specially positioned and oriented for accommodating the size and shape of the wheelchair and the seated position of the user, while at the same time isolating the user&#39;s muscles in an effective manner. The result of this high degree of specialization is that conventional “wheelchair friendly” machines have traditionally exhibited a lack of versatility. Most of these machines are very large and very expensive, but are only capable of facilitating a single type of exercise. A wheelchair-bound individual must therefore use a variety of different specialized machines to perform a complete workout. Moreover, most weight machines that are designed for accommodating wheelchairs are poorly suited for users who do not use wheelchairs. Therefore, in order for a training facility to provide a complete array of wheelchair friendly equipment, the facility must spend a great deal of money and allocate a great deal of floor space to purchase and accommodate a plurality of machines that are largely unusable by the non-wheelchair-bound majority of its clientele. Such an investment is not economically practical for most facilities, thus leaving wheelchair-bound individuals with limited and ill-suited options for weight training. 
   It is therefore desirable to have a weight training machine that can be easily and effectively used by handicapped individuals and non-handicapped individuals alike that is able to facilitate a wide variety of different exercises. 
   BRIEF SUMMARY OF THE INVENTION 
   The present invention relates to a weight lifting machine that incorporates several features for allowing both able-bodied users and users with limited mobility and/or dexterity to easily and effectively perform a wide variety of weightlifting exercises. 
   The apparatus of the present invention preferably includes a central housing with two weight stacks enclosed therein. Two extension arms are pivotably mounted to opposite sides of the housing. Each arm can be releasably locked in a pivoted position relative to the housing. Each arm has a cable guide that can be slidably moved and releasably locked along the length of its respective arm. Cables are linked to each weight stack and extend to the cable guides through a series of pulleys in the manner of a conventional weightlifting machine. A user may thus connect a user interface, such as a handlebar, rope, or strap to the cables for performing various exercises. It is preferred that the cables terminate in J-hooks so that a user with limited manual dexterity can easily connect and disconnect various user interfaces. 
   By adjusting the angular positions of the extension arms relative to the housing and the longitudinal positions of the cable guides relative to the arms, the configuration of the apparatus can be modified to accommodate users of all body types, as well as to facilitate a broad range of weight machine exercises, such as curls, pull downs, crossovers, shrugs, and presses. 
   Button-operated push-locks are preferably mounted to the apparatus for allowing the adjusted positions of the extension arms and the cable guides to be releasably secured. Each of the push-locks operates in the manner of a conventional click-pen and allows a user to lock and unlock the positions of the arms and the guides by successively pressing a button. The push-locks are incorporated as an alternative to conventional, spring-loaded locking pins for allowing users with diminished finger dexterity to easily adjust and secure the configuration of the apparatus. 
   A resistance assembly is preferably located within the central housing and includes a solenoid tower having two solenoid driven pins mounted to vertically movable tracks. The solenoid tower is operatively connected to a user interface located on the front of the housing. The user interface is provided with a plurality of buttons that each correspond to weight increments of the weight stacks in the central housing. When a user presses a button that corresponds to a desired weight increment, the solenoid tower shifts locking pins into engagement with the appropriate weights in the weight stacks to offer the desired amount of resistance. The solenoid tower and the user interface are provided as an alternative to conventional, spring-loaded locking pins for allowing users with diminished finger dexterity to easily adjust the amount of resistance provided by the apparatus. 
   An adjustable support pad preferably extends from the front of the central housing for restricting the movement of a user relative to the central housing and allowing a user to isolate specific muscle groups while performing a workout. The pad can preferably be extended, retracted, and vertically pivoted relative to the housing for accommodating different users and different exercises. Button-operated solenoids are preferably provided for allowing a user to easily lock the pad in various positions along its range of motion. 
   A wheelchair stabilization member preferably extends from the base of the central housing and preferably includes a plurality of retractable cables that extend from two laterally-opposing arms. Each cable terminates in a fastening hook and can be releasably locked in an extended position by a button-operated lock. A user can secure his wheelchair against movement relative to the central housing by positioning his wheelchair between the arms, extending the retracting cables from the arms, mounting the fastening hooks to his wheelchair, and locking the cables with the button-operated locks. 
   A sliding bench is preferably provided by allowing non-wheelchair bound users to operate the apparatus in a seated position. The bench incorporates a spring-loaded catch that mates with a docking bar on the central housing for locking the bench to the housing. A handle preferably protrudes from the front of the bench and is operatively coupled to the catch for allowing a user to unlock the bench from the housing by pulling the handle. 

   
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       FIG. 1  is a perspective view illustrating the preferred embodiment of the present invention. 
       FIG. 2  is a right side view illustrating the preferred embodiment of the present invention shown in  FIG. 1 . 
       FIG. 3  is a front view illustrating the preferred embodiment of the present invention shown in  FIG. 1  with user interfaces attached and in extended positions. 
       FIG. 4  is a right side view illustrating the preferred embodiment of the present invention shown in  FIG. 1  with a number of weight plates shown in an elevated position and with the sliding bench removed. 
       FIG. 5  is a top view illustrating the preferred embodiment of the present invention shown in  FIG. 1  with the sliding bench removed. 
       FIG. 6  is a perspective view illustrating the mounting bracket and push-lock of the left extension arm of the preferred embodiment of the present invention. 
       FIG. 7   a  is a detail view of the push-lock of the left extension arm shown in a locked position. 
       FIG. 7   b  is a detail view of the push-lock of the left extension arm shown in an unlocked position. 
       FIG. 8  is a perspective view illustrating the left arm of the preferred embodiment of the present invention with the proximal end of the arm shown in phantom. 
       FIG. 9  is a front view illustrating the left arm of the preferred embodiment of the present invention with the positioning cam and the positioning aid show in phantom. 
       FIG. 10  is a front view illustrating the positioning cam and positioning aid of the left extension arm of the preferred embodiment of the present invention with the left extension arm show in phantom. 
       FIG. 11  is a front view illustrating the positioning cam and positioning aid of  FIG. 10  in a rotated position. 
       FIG. 12  is a perspective view illustrating the cable guide of the left arm of the preferred embodiment of the present invention. 
       FIG. 13   a  is a detail view of the push-lock illustrating the cable guide of the left extension arm shown in a locked position. 
       FIG. 13   b  is a detail view of the push-lock illustrating the cable guide of the left extension arm shown in an unlocked position. 
       FIG. 14  is a detail view of the cable guide illustrating the left arm of the present invention with various components shown in phantom. 
       FIG. 15  is cross section view illustrating the interior of the cable guide of the left arm of the present invention. 
       FIG. 16  is a front view illustrating the left arm of the present invention with a user interface mounted to the cable. 
       FIG. 17  is a front view illustrating the cable guide of the left arm of the present invention with a user interface mounted to the cable. 
       FIG. 18  is a detail view illustrating the resistance assembly of the present invention. 
       FIG. 19  is a detail view illustrating a pin driver of the resistance assembly shown in  FIG. 18  with the pin disengaged from a weight plate. 
       FIG. 20  is a detail view illustrating the pin driver of  FIG. 19  with the pin engaging a weight plate. 
       FIG. 21  is a detail view illustrating a two-piece pin of the present invention with the locking pin removed from the driving pin. 
       FIG. 22  is a detail view illustrating a two-piece pin shown in  FIG. 21  with the locking pin axially engaging the driving pin. 
       FIG. 23  is a detail view illustrating a weight stack of the present invention with several of the weight plates in an elevated position. 
       FIG. 24  is a right side view illustrating a solenoid tower of an alternative embodiment of the present invention. 
       FIG. 25  is a right perspective view illustrating the support pad of the present invention. 
       FIG. 26  is a right side detail view illustrating the support pad of the present invention with various components of the pad shown in phantom. 
       FIG. 27  is a right side detail view illustrating the support pad of  FIG. 26  in an extended position. 
       FIG. 28  is a left perspective view illustrating the support pad of the present invention. 
       FIG. 29  is a left side detail view illustrating the support pad of the present invention with various components of the pad shown in phantom. 
       FIG. 30  is a left side detail view illustrating the support pad of  FIG. 26  in a pivoted position. 
       FIG. 31  is a perspective view illustrating the wheelchair stabilization member of the present invention. 
       FIG. 32  is a top view illustrating the wheelchair stabilization member of the present invention. 
       FIG. 33  is a cross-sectional view illustrating the left arm of the wheelchair stabilization member of the present invention with the push-lock shown in an unlocked position. 
       FIG. 34  is a cross-sectional view illustrating the left arm of the wheelchair stabilization member of the present invention with the push-lock shown in a locked position. 
       FIG. 35  is a cross-sectional view illustrating the sliding bench of the present invention. 
       FIG. 36  is a detail view illustrating the connective portion of the sliding bench shown in  FIG. 35  with the catch in a locked position. 
       FIG. 37  is a detail view illustrating the connective portion of the sliding bench shown in  FIG. 35  with the catch in an unlocked position. 
       FIG. 38  is a perspective view illustrating the present invention being used to perform a pull down exercise. 
       FIG. 39  is a perspective view illustrating the present invention being used to perform a curl exercise. 
   

   In describing the preferred embodiment of the invention which is illustrated in the drawings, specific terminology will be resorted to for the sake of clarity. However, it is not intended that the invention be limited to the specific term so selected and it is to be understood that each specific term includes all technical equivalents which operate in a similar manner to accomplish a similar purpose. For example, the word connected or terms similar thereto are often used. They are not limited to direct connection, but include connection through other elements where such connection is recognized as being equivalent by those skilled in the art. 
   DETAILED DESCRIPTION OF THE INVENTION 
   As shown in  FIGS. 1-4 , the exercise machine  10  is generally provided with a central housing  12 , pivoting extension arms  14  and  16 , sliding cable guides  18  and  20 , independent cable systems  22  and  24 , user interfaces  26  and  28 , a resistance assembly  30 , an adjustable support pad  32 , a wheelchair stabilization member  34 , and a sliding bench  36 . For the sake of convenience and clarity, terms such as “front,” “rear,” “top,” “bottom,” “up,” “down,” “inwardly,” “outwardly,” “lateral,” and “longitudinal” will be used herein to describe the relative placement and orientation of various components of the invention, all with respect to the geometry and orientation of the machine  10  as it appears in  FIG. 1 . Said terminology will include the words specifically mentioned, derivatives thereof, and words of similar import. 
   The central housing  12  is a vertically elongated, generally rectangular enclosure having a base  38 , a front wall  40 , a rear wall  42 , and a top  44  that are preferably formed of steel, although all other sufficiently rigid and durable materials, including, but not limited to aluminum, plastic, and various composites, are contemplated. The housing  12  additionally includes two removable sidewalls  46  and  48  (sidewall  46  is not within view, but is substantially identical to sidewall  48 ) that are preferably formed of polymethyl methacrylic (PMMA or “acrylic glass”). The sidewalls  46  and  48  prevent users from extending their limbs into the interior of the housing  12  while providing visibility of the resistance assembly  30  and cable systems  22  and  24  (described in greater detail below). Although it is preferred that the sidewalls  46  and  48  be formed of a transparent or partially transparent material, it is contemplated that the sidewalls  46  and  48  can be formed of any suitably rigid material, including, but not limited to steel, aluminum, glass, and various composites. The sidewalls  46  and  48  are mounted to the rest of the housing  12  by any conventional means, such as by removable fasteners, magnetic brackets, and/or hinges. One or both of the sidewalls  46  and  48  may thus be removed or pivoted open for allowing convenient access to the interior of the housing  12  for maintenance or repair. It is contemplated that one or both of the sidewalls  46  and  48  may alternatively be omitted, thereby leaving the interior of the housing  12  exposed. 
   Referring to  FIGS. 3 ,  4 , and  23 , each of the user interfaces  26  and  28  is coupled to one of the weight stacks  50  and  52  by a cable system  22  and  24  in the manner of a conventional exercise machine. In particular, each cable system  22  and  24  includes a flexible member  54  and  56  that extends from a user interface  26  and  28  and operatively engages a series of pulleys that is located in the extension arms  14  and  16  and within the central housing  12 . Pulleys  58  and  60  in each series are mounted to lift shafts  74  and  76  (lift shaft  74  is not within view, but is substantially identical to shaft  76 ) that engage the weight stacks  50  and  52 , respectively. When secured to a selected weight plate by a locking pin (described in greater detail below) each lift shaft  74  and  76  causes any tensile force applied to its corresponding user interface  26  and  28  to be transmitted to the lift shaft&#39;s respective weight stack  50  and  52 . The flexible members  54  and  56  are formed of nylon cable, although various other flexible members including metal cables, ropes, cords, and chains of suitable tensile strength are contemplated. 
   Each weight stack  50  and  52  includes a plurality of conventional weight plates  62  and  64  that are slidably mounted on vertical support shafts  66 ,  68 ,  70 , and  72  (See  FIG. 23 : shaft  66  is not within view, but is substantially identical to shafts  68 - 72 ). The configuration of the pulleys within the central housing  12  causes any force that is transmitted through either flexible member  54  and  56  to be directed toward lifting a predetermined number of weight plates of a corresponding weight stack  50  and  52  upwardly on a lift shaft  74  and  76 , along the support shafts  66 - 72 . Although a particular configuration of pulleys, flexible members, and weight stacks is represented in the previously described figures, it will be appreciated that various other conventional and equivalent configurations are contemplated for achieving similar operative relationships. For example, it is contemplated that a single flexible member can be used to link both user interfaces to a single weight stack. 
   Referring now to  FIG. 3 , the extension arms  14  and  16  are coupled to the mounting brackets  78  and  80  that extend laterally from opposite sides of the front wall  40 . The cable guides  18  and  20  fit over the extension arms  14  and  16  for allowing the user interfaces  26  and  28  to be adjustably positioned relative to the arms  14  and  16 . The extension arms  14  and  16 , mounting brackets  78  and  80 , cable guides  18  and  20 , and user interfaces  26  and  28  on either side of the exercise machine  10  are substantially identical, and will now be described with reference to the components on the left side of the machine  10  only. Referring to  FIGS. 5 and 6 , the mounting bracket  78  is a generally U-shaped member (as viewed from above) that includes front and rear mounting plates  81  and  82 . The plates  81  and  82  are vertically oriented and are parallel to one another to form a vertical channel  84  of predetermined width therebetween. The plates  81  and  82  extend forward from the housing  12  at a preferred angle of about 30 degrees, although any angle in the range of about 0 degrees to about 90 degrees is contemplated. 
   The extension arm  14  is an elongated, hollow, and generally rectangular member. The arm  14  is preferably about four feet in length, although any length in a range of about 2 feet to about 8 feet is contemplated. The extension arm  14  has a proximal end  86  nearest the central housing  12  and a distal end  88  furthest from the housing. The arm  14  has an elongated cable slot (not within view) formed in its bottom surface that extends from adjacent the proximal end  86  to adjacent the distal end  88 . The proximal end  86  of the arm  14  fits within the vertical channel  84  of the mounting bracket  78  and is pivotably mounted therein by an axle pin  90  that extends perpendicularly between, and that is rigidly mounted to, the front and rear mounting plates  81  and  82 . The pin  90  extends through the extension arm  14  and engages conventional replaceable bearings located therein for allowing the arm  14  to smoothly pivot 90 degrees in either direction from the orientation shown in  FIG. 3 . The width of the extension arm  14  is substantially equal to the width of the vertical channel  84  for providing snug engagement between the arm  14  and the mounting bracket  78  without inhibiting the rotational movement of the arm  14 . 
   Referring to  FIG. 8 , the extension arm  14  has a plurality of arm positioning holes  92  formed in its front surface in an evenly spaced, circular pattern coaxial with the axle pin  90 . The locations of the positioning holes  92  correspond to securable angular positions of the extension arm  14  (described in greater detail below). 
   Referring to  FIGS. 6-8 , a push-lock  94  is located on the front plate  81  of the mounting bracket  78  intermediate the axle pin  90  and the edge of the bracket  78 . The push-lock  94  is a spring-loaded locking mechanism that is generally provided with a button  96 , a shaft  98 , a spring  100 , and a catch (not pictured). The push-lock  94  operates in the manner of a conventional click-pen, allowing a user to move the shaft  98  axially between a locked position (as shown in  FIG. 7   a ) and an unlocked position (as shown in  FIG. 7   b ) by pressing or striking the head with a moderate amount of force. For example, if the push-lock  94  is in an unlocked position and a user exerts sufficient axial force on the button  96  to overcome the resistance of the spring  100 , the spring  100  becomes compressed, which forces the catch into engagement with the spring  100 , thereby securing the shaft  98  in a locked position. Conversely, if the push-lock  94  is in a locked position and a user exerts sufficient axial force on the button  96  to overcome the resistance of the partially compressed spring  100 , the spring  100  is compressed further, which forces the catch to release the spring  100 , thereby allowing the spring  100  and the shaft  98  to extend to their unlocked positions. 
   The push-lock  94  is thus used as a convenient substitute for a conventional locking pin of the type commonly used in traditional exercise machines for adjustably securing component positions and weight increments. Unlike a locking pin, the push-lock  94  can be easily operated by users having limited manual dexterity. Whereas the manipulation of a conventional locking pin requires a great deal of finger dexterity, the push-lock requires little or no manual dexterity and can be easily operated with a fist, the flat of a hand, a forearm, or even an elbow. 
   Referring to  FIGS. 7   b  and  8 , the shaft  98  of the push-lock  94  is axially aligned with an arm locking hole  102  formed in the front plate  81 . The distance between the locking hole  102  and the axle pin  90  is equal to the radius of the circle about which the arm positioning holes  92  are disposed. By pivoting the extension arm  14  about the axle pin  90 , the various positioning holes  92  can be arcuately shifted into and out of axial alignment with the arm locking hole  102 . When a positioning hole corresponding to a desired angular position of the extension arm  14  is moved into alignment with the locking hole  102 , the push-lock  94  can be engaged, thereby forcing the shaft  98  of the push-lock  94  into axial engagement with the two holes and locking the arm  14  against further angular movement. 
   Referring to  FIGS. 9-11 , a positioning cam  104  is located within the extension arm  14  adjacent the proximal end  86  of the arm  14 . The cam  104  is rigidly mounted to the axle pin  90 , and thus remains in a fixed orientation when the arm  14  is pivoted about the pin  90 . The cam has a semi-circular, outwardly directed edge that features a plurality of evenly spaced, radially extending detents  106 . Like the arm positioning holes  92 , each of the detents  106  corresponds to a securable angular position of the extension arm  14  (described in greater detail below). 
   An adjustable, spring-loaded positioning aid  108  is located within the arm  14  adjacent the positioning cam  104 . The positioning aid  108  generally includes a bearing  110 , a bearing mount  112 , a spring  114 , a threaded adjustment screw  116 , a fixed washer  117 , and an adjustment washer  118 . The fixed washer  117  is rigidly mounted to the interior of the arm  14  and its axis is radially oriented with respect to the axle pin  90 . The adjustment screw  116  threadedly engages the fixed washer  117  and can be longitudinally displaced relative to the washer  117  by rotating the screw  116  about its axis. The adjustment washer  118  is rigidly fixed to adjustment screw  116 . One end of the spring  114  fits over an end of the adjustment screw  116  and abuts the adjustment washer  118 . The bearing mount  112  is rigidly affixed to the opposite end of the spring  114 . The bearing  110  is a circular body that is rotatably mounted to the bearing mount  112  by an axle pin  120 , thereby allowing the bearing  110  to rotate freely about its axis. The spring  114  holds the bearing  110  in firm engagement with the positioning cam  104 . The amount of force exerted on the positioning cam  104  by the bearing  110  may thus be increased or decreased by rotating the adjustment screw  116  clockwise or counterclockwise about its axis to compress or decompress the spring  114 . 
   When a user pivots the extension arm  14  about the axle pin (as indicated by the curved arrow in  FIG. 11 ), the spring  114  compresses and extends (as indicated by the longitudinal arrow in  FIG. 11 ) as the bearing  110  moves over and between the detents  106  of the cam  104 . The engagement between the bearing  110  and the detents  106  provides a user with a palpable sensation as the user adjusts the angular position of the arm  14 . Specifically, the arm  14  is slightly more difficult to rotate when the bearing  110  is moving over a detent  106  than when the bearing  110  is moving into a space between the detents  106 . The detents  106  are positioned to indicate axial alignment between the arm locking hole  102  and an arm positioning hole  92  whenever the bearing  110  is positioned between two of the detents  106 . A user is thus able to tell by manual sensation when the push-lock  94  can be effectively engaged in order to secure the arm  14  in a desired position. 
   In addition to providing an indication of alignment between the arm locking hole  102  and the arm positioning holes  92 , the forceful engagement between the bearing  110  and the detents  106  of the cam  104  also acts as a counterbalance to the weight of the extension arm  14 . That is, the radial force provided by the spring  114  is great enough to hold the bearing  110  in place between two of the detents  106  against the force of gravity acting on the extension arm  14 . Thus, when a user unlocks the push-lock  94 , the arm  14  will stay in place until the user shifts the arm  14  manually. 
   An alternative embodiment of the invention is contemplated in which the extension arm  14  is provided with a conventional counterweight on the proximal end of the arm  14  for allowing the arm  14  to be easily articulated by a user with the application of relatively little force. The counterweight can be formed of lead, iron, or any other suitably heavy material for counteracting the weight of the arm  14 . The counterweight can be provided in addition to, or in lieu of, the spring-loaded positioning aid  108  described above. Alternatively, the arm  14  can be moved by a prime mover or any conventional power-operated device. 
   Referring to  FIG. 6 , a plurality of radially disposed alignment dots  122  are provided on the front surface of the front mounting plate for allowing a user to readily ascertain visually whether axial alignment exists between the arm locking hole  102  and an arm positioning hole  92 . Specifically, the alignment dots are positioned to indicate axial alignment between the locking hole  102  and one of the positioning holes  92  when any of the dots  122  are longitudinally aligned with the guide cuff positioning holes  156  (described in greater detail below). A user is thus provided with a clear visual indication of alignment in addition to the palpable indication of alignment provided by the spring-loaded positioning aid  108 . 
   The alignment dots  122  are preferably painted circles, although it is contemplated that any other visual indicia may alternatively be used to achieve the functionality described above, including, but not limited to holes, notches, ridges, tabs, depressions, and raised areas of various shapes and sizes. 
   Referring now to  FIGS. 12-15 , the cable guide  18  includes a guide cuff  128 , a pivot extension  130 , and a push-lock  132 . The guide cuff  128  is a generally rectangular body having an opening that receives the extension arm  14  therethrough. The interior dimensions of the cuff  128  are slightly larger than the exterior dimensions of the extension arm  14  for permitting the guide cuff  128  to surround and slidably engage the arm  14 . Thus, the cuff  128  snugly engages the extension arm  14  while allowing longitudinal sliding movement of the cuff  128  relative to the arm  14  for adjustment. The cuff  128  has a cable port  134  formed in its bottom wall. A cable termination bracket  136  extends upwardly from the bottom of the cuff  128 , through an elongated cable slot formed in the bottom of the extension arm (not within view), and into the interior of the extension arm  14 . A first end of the flexible member  54  is permanently affixed to the cable termination bracket  136 , and a second end of the flexible member  54  extends downwardly from the cable slot and through the cable port  134 . 
   The pivot extension  130  is a generally rectangular, hollow body that is pivotably mounted to the bottom of the guide cuff  128  by a hinge  138 . The hinge  138  allows the extension  130  to freely pivot 180 degrees backwards and forwards (90 degrees in both directions from the position shown in  FIG. 15 ). Two opposing pulleys  140  and  142  are rotatably mounted within the pivot extension  130  in a longitudinally close clearance relationship to form a vertical channel  144  therebetween. A cable inlet port  146  and a cable outlet port  148  are formed in the top and bottom surfaces of the pivot extension  130 , respectively, for providing a vertical passageway through the extension  130 . The flexible member  54  extends downwardly from the cable port  134  into the pivot extension  130 , between the opposing pulleys  140  and  142 , and terminates in a J-hook  146  (described in greater detail below) below the pulleys  140  and  142 . The flexible member  54  thus extends from the J-hook  146 , through the outlet port  134 , around a first pulley  148 , to the distal end  88  of the extension arm  14 , around a second pulley  150 , back to the proximal end  86  of the arm  14 , through the rest of the of the cable system  22 , back to the proximal end  86  of the arm  14 , and finally terminates at the cable termination bracket  136 . 
   Given the configuration of the cable guide  18  and positions of the two ends of the flexible member  54 , any longitudinal movement of the guide  18  along the extension arm  14  results in a corresponding longitudinal movement of the ends of flexible member  54 . The result of this relationship is that the guide  18  can be moved along the extension arm  14  while the flexible member  54  remains substantially taught, thereby obviating the need for any type of cable take-up means. For example, if the cable guide  18  is moved from the distal end  88  of the arm  14  toward the proximal end  86  of the arm  14 , the movement of the first end of the flexible member  54  toward the housing  12  causes the member  54  to slacken, while the movement of the second end of the flexible member  54  toward the housing  12  simultaneously causes the member  54  to be pulled taught by an equal amount. The movement of the ends thus causes the entire flexible member  54  to cycle around all of the pulleys in the cable system  22 . 
   Referring to  FIGS. 12 ,  13   a , and  13   b , the push-lock  132  is located on the front of the guide cuff  128 . The push-lock  132  is substantially identical in structure and in function to the push-lock  94  described above. The shaft of the push-lock  132  is axially aligned with a guide cuff locking hole  154  that is formed in the front surface of the guide cuff  128 . The extension arm  14  has a plurality of evenly spaced, longitudinally disposed guide cuff positioning holes  156  along its length. The guide cuff locking hole  154  is longitudinally aligned with each of the guide cuff positioning holes  156 . In order to adjust the longitudinal position of the cable guide  18  relative to the extension arm  14 , the guide cuff  128  is slid along the arm  14  while the push-lock  132  is in an unlocked position. When the desired position of the guide cuff  128  is reached, the cuff  128  is further adjusted to bring the guide cuff locking hole  154  into axial alignment with a nearest guide cuff positioning hole. The head of the push-lock  132  is then depressed, thereby forcing the shaft through the guide cuff locking hole  154  and into axial engagement with the selected guide cuff positioning hole  156  and securing the push-lock  132  in a locked position. The guide cuff  128  is thereby fixed against longitudinal movement along the extension arm  14  until the push-lock  132  is unlocked. 
   Referring now to  FIG. 17 , the user interface  26  is operatively connected to the J-hook  146  by extending one end of the J-hook through an attachment ring  160 . The user interface shown is a conventional cable machine handle, although it is contemplated that the interface can be any of a variety of conventional cable machine attachments that will be recognized by those skilled in the art, including a lateral bar, a curl bar, or an ankle cuff, or any other structure that the user of the machine  10  engages to enable the user to apply a tensile force to the flexible member  54 . 
   The J-hook  146  is incorporated as a substitute for a conventional carabineer clip of the type commonly employed in traditional exercise machines for attaching user interface components to a flexible member. As with the push-locks  94  and  132  described above, the J-hook  146  is in important feature for allowing users who have limited manual dexterity to easily attach and remove interface components. Whereas a carabineer clip requires intricate manual manipulation to fasten and unfasten, the J-hook  146  allows a user to simply place the attachment ring  160  of a user interface over the point of the hook  146 . In addition to being easy to use, the J-hook  146  maintains secure engagement with the attachment ring of a user interface under significant loads. Although the J-hook is the preferred means for securing a user interface to the flexible member, various other hooks, clips, and removable fasteners, including conventional carabineer clips, are contemplated. 
   Referring now to  FIGS. 18-23 , the resistance assembly  30  includes a pin tower  162 , two pin drivers  164  and  166 , and a selection interface  168 . The pin tower  162  is a vertically elongated housing that is positioned horizontally intermediate the weight stacks  50  and  52 . The pin drivers  164  and  166  are mounted to the front and rear of the pin tower  162  in a vertically movable relationship. The pin drivers  164  and  166  are substantially identical, and will now be described with reference to the pin driver  166  on the rear of the pin tower  162 . The pin driver  166  includes a conventional solenoid  170  and a two-piece pin  172 . The solenoid has a coil  174 , a spring  176 , and a retention collar  178 . The two-piece pin  172  is defined by a driving pin  180  and a locking pin  182 . The driving pin  180  axially engages the coil  174  and is held in place by the spring  176  and the retention collar  178 . The spring  176  biases the driving pin  180  away from the weight stack  52 . 
   The driving pin  180  is provided with a head  184  having a larger diameter than the shaft  186  of the pin  180 . The locking pin  182  has a rounded claw  188  with an interior recess  190  for matingly engaging the shaft  186  and the head  184  of the driving pin  180 , respectively. The claw  188  fits over the shaft  186  from above and the head  184  fits into the recess  188  from below, thereby providing secure axial engagement between the driving pin  180  and the locking pin  182  while allowing the locking pin  182  to be moved upwardly, off of the driving pin  180 . 
   The pin tower  160  houses a control unit and a drive system (not shown). The control unit is configured to receive electrical signals from the selection interface  168  for controlling the drive system and the pin driver  166 . The drive system moves the pin driver  166  vertically, along recessed tracks in the pin housing (not within view) in response to command signals from the control unit. The control unit can be any type of conventional control unit, including, but not limited to a microcontroller and programmable logic controller. The drive system can be any type of conventional drive system, such as a combination of a conventional servo motor, a conventional series of sprockets or pulleys, and drive chains or belts. 
   The selection interface  168  is located on the front of the central housing  12  and includes an energized key pad  192  having a plurality of numbered buttons  194  representing the weight increments of the weight stack  52 . The interface  168  is electrically coupled to the control unit in the pin tower  162  by a control wire  196 . When one of the buttons  194  on the keypad  192  is depressed, an electrical signal is transmitted through the control wire  196  for communicating the selected weight value to the control unit. The control unit then activates the drive system to vertically shift the pin driver  166  until the locking pin  182  is in axial alignment with a pin channel  197  in the proper weight plate. For example, if each of the weight plates weighs 10 pounds, and the user depresses the 10 pound key on the key pad  192 , the pin driver  166  will be shifted until the locking pin  182  is in axial alignment with the pin channel  197  in the top weight plate of the weight stack  52 . Once the locking pin  182  is properly positioned, the control unit energizes the coil  174  of the solenoid  170 . The solenoid  170  then imparts an axial force on the driving pin  180  that is sufficient to overcome the resistance of the spring  176 , thereby forcing the driving pin  180  laterally toward the weight stack  52  and shifting the locking pin  182  into axial engagement with the pin channel  197  of the weight plate and a corresponding pin hole in the lift shaft  76  (as shown in  FIG. 20 ). As a user exercises and applies a lifting force to the lift shaft  76 , the selected weight plates, and the locking pin  182  travel up and down along the vertical shafts  70  and  72 . The engagement between the recessed claw  190  of the locking pin  182  and the head  184  of the driving pin  186  allows the locking pin  182  to be freely lifted off of the driving pin  180  (as shown in  FIG. 23 ) and then returned. 
   When the user has completed his exercise, the selected weights are brought to rest on the weight stack  52  and the locking pin  182  is brought back into engagement with the driving pin  180 . When the user selects a different weight increment on the keypad  192 , the control unit de-energizes the solenoid  170 , which allows the spring  176  to force the driving pin  180  away from the weight stack  52 , thereby drawing the locking pin  182  out of the pin channel of the previously selected weight plate. The process described above is then repeated for selectively engaging another weight plate. 
   Referring to  FIG. 24 , an alternative embodiment of the invention  10  is shown in which the drive system of the embodiment described above is omitted and in which the pin tower is provided with a pin driver for each weight plate in the weight stacks. The position of the solenoid of each pin driver is fixed relative to the pin tower, and the locking pin of each driver is axially aligned with the pin hole of a weight plate. When a particular weight is selected by a user, the solenoids that correspond to the appropriate weight plates are energized. No vertical movement of the pin drivers is necessary in this embodiment. 
   Another alternative embodiment of the invention is contemplated in which conventional hydraulic cylinders are incorporated as an alternative to the solenoids of the pin drivers described above. Yet, another alternative embodiment of the invention is contemplated in which the resistance assembly  30  is entirely omitted, and push-locks, similar to the push-locks  94  and  132  described above, are incorporated for lockably securing the weight plates  62  and  64  of the weight stacks  50  and  52 . Yet another embodiment is contemplated in which conventional locking pins, like those incorporated in traditional weight machines, are used for weight selection. 
   Referring now to FIGS.  1  and  25 - 30 , the adjustable support pad  32  is mounted to the front of the central housing  12  and generally includes a pad  198 , an extension shaft  200 , an extension sleeve  202 , a pivot wheel  204 , an extension locking button  206 , a pivot locking button  208 , and horizontal and vertical pin drivers  210  and  212 . The pivot wheel  204  is rotatably mounted to the interior of the housing  12  by a central axle (not within view) for allowing the wheel  204  to freely rotate about its axis. The wheel  204  is vertically oriented and protrudes slightly through a vertically elongated slot  214  formed in the front surface of the housing  12 . The wheel  204  is preferably a hollow body and has a plurality of evenly spaced, radially disposed positioning holes  216  formed in its curved surface. 
   The extension sleeve  202  is a tubular, generally rectangular body that extends through the pivot wheel  204  and is rigidly mounted thereto. The sleeve  202  preferably protrudes several inches from the front and from the rear of the wheel  204  and provides a rectangular passageway therethrough. The sleeve  202  has a locking hole (not within view) formed in one of its sidewalls for providing a horizontal passageway therethrough. 
   The extension shaft  200  is an elongated, generally rectangular body having exterior dimensions that are substantially equal to the interior dimensions of the extension sleeve  202 . The shaft  200  fits axially within the extension sleeve  202  in a close clearance relationship for allowing the shaft  200  to slide axially relative to the sleeve  202 . The shaft  200  has a plurality of evenly spaced, longitudinally disposed positioning holes  218  formed in one of its sidewalls for providing a plurality of horizontal passageways therethrough. The positioning holes  218  are longitudinally aligned with the locking hole in the extension sleeve  202 , thus allowing various positioning holes to be moved into and out of axial alignment with the locking hole by sliding the shaft  200  relative to the sleeve  202 . 
   The pad  198  is an elongated cylindrical body that is defined by a rigid support member  219  covered with a layer of dense foam padding  221 . The pad  198  is rigidly mounted to the front end of the extension shaft  200 . Although it is preferred that the pad  198  be cylindrical in shape, it is contemplated that the pad  198  can be a variety of other shapes, including, but not limited to rectangular, triangular, or irregularly shaped to accommodate contoured engagement with various parts of a user&#39;s body as will be appreciated by those skilled in the art. It is further contemplated that the pad  198  may be formed of any another type of suitable material and can incorporate any another type of suitable covering, including, but not limited to various plastics, foams, fabrics, and rubber. 
   The horizontal pin driver  210  is substantially identical in structure and in function to the pin driver  166  described above but has a one-piece pin (not within view) instead of a two-piece pin. The horizontal driver  210  is rigidly mounted to the exterior of the pivot wheel  204  with the one-piece pin axially aligned with and directed toward the locking hole in the extension sleeve  202 . The extension locking button  206  is located on the right side of the support pad  32 , although it is contemplated that the button  206  can be located anywhere on the machine  10 . The pin driver  210  is electrically connected to the extension locking button  206  by a control wire  220  that passes longitudinally through the extension shaft  200 . By successively pressing the extension locking button  206 , a user can energize and de-energize the solenoid of the horizontal driver  210 , thus extending and retracting the one-piece pin into and out of engagement with the locking hole. For example, in order to adjust and secure the longitudinal position of the support pad  32 , a user shifts the pad  32  longitudinally until the locking hole is in axial alignment with one of the positioning holes  218 . The user then presses the extension locking button  206 , which causes the pin to shift axially through an aperture formed in the side of the pivot wheel  204  and into axial engagement with the locking hole and the selected positioning hole. The longitudinal position of the support  32  pad is thereafter fixed until the locking button  206  is pressed again, at which time the one-piece pin will be withdrawn from the holes. 
   The vertical pin driver  212  is substantially identical in structure and in function to the horizontal pin driver  210 . The vertical driver  212  is rigidly mounted to the interior of the central housing  12  adjacent the pivot wheel  204  and has a one-piece pin  222  that is vertically oriented and longitudinally aligned with the positioning holes  216  in the wheel  204 . The pivot locking button  208  is located on the left side of the support pad  32 , although it is contemplated that the button  208  can be located anywhere on the machine  10 . The pin driver  212  is electrically connected to the pivot locking button  208  by a control wire  224  that passes longitudinally through the extension shaft  200 . By successively pressing the pivot locking button  208 , a user can energize and de-energize the solenoid of the vertical driver  212 , thus extending and retracting the one-piece pin  222  into and out of engagement with a selected positioning hole in the pivot wheel  204 . For example, in order to adjust and secure the pivoted position of the support pad  32 , a user pivots the pad  32  about the central axle until the one-piece pin  222  is in axial alignment with one of the positioning holes  216 . The user then presses the pivot locking button  208 , which causes the pin  222  to shift into axial engagement with the selected positioning hole. The pivoted position of the support pad  32  is thereafter fixed until the locking button  208  is pressed again, at which time the one-piece pin  222  will be withdrawn from the positioning hole. 
   An alternative embodiment of the invention is contemplated in which conventional hydraulic cylinders are incorporated as an alternative to the solenoids of the horizontal and vertical pin drivers  210  and  212  described above. Another alternative embodiment of the invention is contemplated in which the vertical and horizontal pin drivers  210  and  212  are omitted, and push-locks, similar to the push-locks  94  and  132  described above, are incorporated for lockably engaging the positioning holes  216  and  218  of the extension shaft  202  and the pivot wheel  204 . Yet another embodiment is contemplated in which conventional locking pins, like those incorporated in traditional weight machines, are used for securing the extended and pivoted positions of the support pad  32 . It should be noted that all other conventional means for isolating and restricting the movement of a user relative to the central housing  12  may be incorporated in addition, or as an alternative, to the support pad  32  without departing from the spirit of the invention. 
   Referring now to FIGS.  1  and  31 - 34 , the wheelchair stabilization member  34  is a U-shaped body having two arms  226  and  228  that extend forward from the base  38  of the central housing. The arms  226  and  228  are spaced apart from one another a sufficient distance for allowing a wheelchair  230  of conventional size to easily fit therebetween (as shown in  FIG. 31 ). The arms  226  and  228  are substantially identical to one another, and will now be described with reference to the left arm  226  only. A spooling member  229  is located within the arm  226  and generally includes proximal and distal spools  232  and  234 , proximal and distal retracting cables  236  and  238 , a master axle  240 , a locking gear  242 , and a push-lock  244 . 
   The proximal and distal spools  232  and  234  are positioned adjacent proximal and distal cable apertures  246  and  248  that are formed in the inward-facing surface of the arm  226 . The spools  232  and  234  are vertically oriented (with their axes substantially horizontal) and are rigidly mounted to the master axle  240 . The ends of the master axle  240  are rotatably mounted to the interior of the arm  226 , such as by mounting in conventional replaceable bearings, for allowing the axle  240 , and therefore the spools  232  and  234 , to rotate freely about a common horizontal axis. 
   The proximal and distal retracting cables  236  and  238  are each mounted at one end to the proximal and distal spools  232  and  234 , respectively, and terminate in fastening hooks  248  and  250  at their opposite ends. The spools  232  and  234  are rotatably spring-loaded in the manner of a retractable lanyard for keeping the cables  236  and  238  fully wound about the spools  232  and  234  when there is no tensile force applied to the cables  236  and  238 . Thus, when a sufficient amount of tensile force is applied to a cable, the resistance of the cable&#39;s respective spring can be overcome and the cable can be extended through its corresponding cable aperture. When the tensile force is relaxed, the spool is allowed to rotate in the direction in which it is biased by its spring, thereby pulling the cable back through the aperture and recollecting it about the spool. 
   The locking gear  242  is rigidly mounted to the master axle  240  in a manner similar to the spools  232  and  234 . The gear  242  is vertically oriented and has a plurality of radial gear teeth (not shown). The push-lock  244 , which is substantially identical to the push-locks  94  and  132  described above, is mounted to the top surface of the arm  226  and is axially aligned with a locking hole  252  formed therethrough. Thus, when the push-lock  244  is in a locked position (as shown in  FIG. 34 ) the shaft of the lock extends through the locking hole  252  and terminates intermediate two of the gear teeth. The gear  242  is thereby prevented from rotating, which in turn prevents the master axle  240  and the spools  232  and  234  from rotating. 
   To use the wheelchair stabilization member  34 , a user moves his wheelchair  230  between the arms  226  and  228  and positions the chair  230  properly to facilitate a desired exercise. The user then grasps a loop handle  256  that extends from one of the hooks  248  and  250 . The loop handles  254  and  256  are provided for allowing users with limited manual dexterity to easily pull and manipulate the hooks  248  and  250 . The user then pulls on the handle  256  to extend the hook  250  and the cable  238  toward the wheelchair  230  (as shown in  FIG. 31 ). The hook  250  is then fastened to a front corner of the frame of the wheelchair  230  while the spring-loaded spool  234  keeps the cable  238  taught. The above-described process is repeated with the other hook  248  on the arm  226 , with the hook  248  being fastened to a rear corner of the frame of the wheelchair  230 . Once both hooks  248  and  250  are securely fastened to the wheelchair  230 , the user presses the push-lock  244 , thereby locking the locking gear  242  and preventing the cables  236  and  238  from extending any further from the arm  226 . The proximal retracting cable  236  thus prevents the wheelchair  230  from moving away from the central housing  12 , and the distal retracting cable  238  prevents the wheelchair  230  from moving toward the central housing  12 . Together, the cables  236  and  238  prevent the wheelchair  230  from moving or tipping away from the arm  226 . The spooling member of the opposite arm  228  operates in a similar fashion to restrict the movement of the wheelchair, thus preventing the wheelchair from moving in any direction while all of the cables of the stabilization member  34  are locked. 
   An alternative embodiment of the invention is contemplated in which the push-lock  244  is omitted, and a conventional locking pin, like those incorporated in traditional weight machines, is used for securing the locking gear  242  in the arm  226 . Yet another embodiment of the invention is contemplated in which wheelchair stabilizing member  34  is entirely omitted. It should be noted that all other conventional means for securing the position of a wheelchair relative to the central housing  12  may be additionally or alternatively incorporated without departing from the spirit of the invention. 
   Referring now to FIGS.  1  and  35 - 37 , the sliding bench  36  is provided for allowing non-wheelchair bound users to perform exercises that require a user to be in a seated position. Although the bench  36  is shown as being generally U-shaped, it is contemplated that the bench  36  can have the shape of any conventional freestanding bench, seat, stool, or chair as will be apparent to those skilled in the art. A spring-loaded, pivoting catch  260  with a hooked tongue  262  is rotatably mounted to the forward-most bottom edge of the bench  36  for engaging a docking bar  264  that is rigidly mounted to the base  38  of the central housing  12 . The spring (not shown) of the catch  260  biases the catch  260  toward a down position about an axle pin  266 , as shown in  FIG. 35 . The height of the docking bar  264  relative to the base  38  of the central housing  12  is substantially equal to the height of the tongue  262  relative to the bottom of the bench  36 . To lock the bench  36  to the central housing  12 , a user slides the bench  36  against the housing  12  and brings the tongue  262  into contact with the docking bar  264 . By applying a sufficient amount of lateral force to the bench, a user can overcome the resistance of the catch spring and cause the tongue  262  to pivot upwardly, over the docking bar  264 . Once the hooked tongue  262  has cleared the docking bar  264  and the catch spring has forced the catch  260  back to the down position, the engagement between the tongue  262  and the bar  264  thereafter prevents the bench  36  from moving away from the central housing. 
   A cable  268  extends from the rear of the catch  260  to a handle  270  that protrudes from the rear of the bench  36 . The cable  268  is mounted to the catch  260  above the axle pin  266  and is routed around a series of horizontally oriented shafts  272  within the bench  36 . The configuration of the shafts  272  causes the cable  268  to approach the catch  260  from below the cable&#39;s point of affixation on the catch  260 . Any tensile force in the cable  268  is thus directed toward pulling the catch  260  in a clockwise direction (as shown in  FIG. 37 ) about the axle pin  266 . Therefore, when a user pulls the handle  270  with a sufficient amount of force to overcome the catch spring, the tongue  262  is raised over the docking bar  264  thereby allowing the bench  36  to be freely slid away from the central housing. 
   It is contemplated that the sliding bench  36  can be omitted, and that any type of conventional bench, seat, stool, or chair can be used in its place for supporting a user in a seated position. 
   To operate the exercise machine  10  in a typical fashion, a user first adjusts and locks the angular positions of the extensions arms  14  and  16  and adjusts and locks the longitudinal positions of the cable guides  18  and  20  to facilitate a desired exercise. For example, to accommodate a pull down type exercise, the user locks the arms  14  and  16  in a substantially upward-pointing configuration as shown in  FIG. 38 . To accommodate a curl type exercise, the user locks the arms  14  and  16  in a substantially downward-pointing configuration as shown in  FIG. 39 . Although the positions of the arms  14  and  16  and the cable guides  18  and  20  will generally mirror each other when adjusted to facilitate a particular exercise, a user with limited mobility on one side of his body may wish to configure the arms  14  and  16  and the cable guides  18  and  20  differently, such as in an asymmetric configuration, to accommodate his physical limitations. For example, if the user is unable to fully extend one of his arms, he can move one of the cable guides  18  and  20  closer to the central housing  12  relative to the position of the opposite cable guide. 
   The user then attaches a desired user interface to the J-hook of each of the flexible members  54  and  56 . If the user is wheelchair bound, the user then positions his wheelchair intermediate the arms  226  and  228  of the wheelchair stabilization member  34  in a proper orientation for performing the desired exercise. The user then fastens the retractable cables of the stabilization member  34  to his wheelchair and locks the cables in their extended positions. If the user is not wheelchair bound and wishes to perform an exercise that requires him to be in a seated position, the user locks the sliding bench  36  to the housing  12  and properly positions himself on the bench  36 . 
   The user then adjusts and locks the extended and pivoted positions of the support pad  32  to restrict his movement relative to the housing  12  in a manner that facilitates the desired exercise. The user then selects a desired weight increment on the keypad  192  of the selection interface  168 , thereby causing locking pins to be shifted into engagement with corresponding weight plates in the weight stacks  50  and  52 . 
   The user next engages the user interfaces and performs the desired exercise in a conventional manner, such as by repeatedly applying sufficient force to the flexible members  54  and  56  to overcome to the resistance provided by the selected weight plates. Although the steps herein are described in a particular order, it will become apparent that the steps can be carried in a variety of orders. 
   This detailed description in connection with the drawings is intended principally as a description of the presently preferred embodiments of the invention, and is not intended to represent the only form in which the present invention may be constructed or utilized. The description sets forth the designs, functions, means, and methods of implementing the invention in connection with the illustrated embodiments. It is to be understood, however, that the same or equivalent functions and features may be accomplished by different embodiments that are also intended to be encompassed within the spirit and scope of the invention and that various modifications may be adopted without departing from the invention or scope of the following claims.