Abstract:
A seat assembly can be mounted on various wheelchair bases. The seat assembly enables the seat width and backrest width to be adjusted independently of each other. A backrest has a plurality of open slots, the number and orientation of which contributes to depth, width, and height adjustment of the backrest as well as angular adjustment of lateral supports to permit the backrest to conform to the anatomical curves of a user. A backrest foam assembly comprises multiple foam sections that are adapted to be positioned relative to each other and thereby vary the overall width of the assembly. A cover comprises multiple sections, each covering a foam section. A multi-position adjustable armrest assembly combines large-scale and small-scale adjustments, which provides a broad range of adjustment for the armrest and its position. A power recline mechanism with programmable shear reduction includes a dual rotary recline mechanism.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims the benefit of U.S. Provisional Patent Application No. 60/621,409, filed on Oct. 22, 2004. 
     
    
     BACKGROUND OF INVENTION  
       [0002]     This invention relates in general to personal mobility vehicles and more particularly, to accessories for personal mobility vehicles. Most particularly, this invention relates to seating systems for wheelchairs and like vehicles.  
         [0003]     Conventional seat assemblies for wheelchairs have a seat and a backrest that are not independently adjustable. Such seat assemblies are not well suited for users having apple or pear shaped anatomies (i.e., a normal trunk and wide hips, usually due to redundant tissue). Such users would be better accommodated with a wide seat and narrow backrest. Conventional seat assemblies with a seat and a backrest that are not independently adjustable cannot accommodate such users.  
         [0004]     Conventional seat assemblies also have lateral thoracic supports. However, most of these supports are limited to adjustment in a vertical plane or direction. That is to say, these supports do not accommodate changes in width over the vertical extent of the seat assembly due to asymmetry in the anatomy of the user. However, some conventional lateral supports have been designed as after market components, which are typically mounted externally. What is needed is a seat assembly with integral or integrated components that accommodate irregular shaped users.  
         [0005]     Conventional backrests are covered with a foam and cover that are constructed specifically for the size of the backrest to which the foam and covers are supported. If a user needs a backrest that is a different size, the user would have to acquire another foam and cover to fit that backrest. A backrest is needed that allows a user to make width adjustments to in the foam and cover, especially in modular seating systems.  
         [0006]     Convention seat assemblies employ armrest assemblies that have adjustment features, including height adjustment, width adjustment, depth adjustment and armrest pad angle adjustment. However, conventional armrest assemblies do not incorporate all these adjustment features. An armrest assembly is needed that integrates all these adjustment features so that the armrest can be position to provide maximum benefit to the user.  
         [0007]     Conventional armrest assemblies also utilize incremental height adjustment mechanisms and incremental armrest pad adjustment mechanisms. Some armrest assemblies utilize a threaded fastener for infinite armrest pad angle adjustment but such an adjustment is very limited. An armrest is further needed that is not limited to make incremental adjustments.  
         [0008]     Conventional seat assemblies further require at least two different mechanisms to address recline and shear compensation of the backrest. Also, when the seat assembly is fully reclined, there is an undesirable height differential between the seat and backrest for which there must be compensation. A seat assembly is needed that combines a recline operation and shear compensation in one mechanism. Such a mechanism should also eliminate seat to backrest height differential in full recline through the unique kinematics of the mechanism.  
       SUMMARY OF INVENTION  
       [0009]     The present invention is directed towards a seat assembly for a wheelchair, wherein the seat assembly can be mounted on various wheelchair bases, and more particularly on power wheelchair bases. The seat assembly enables the seat width and backrest width to be adjusted independently of each other.  
         [0010]     The present invention is also directed towards a backrest that has a plurality of open slots, the orientation of which contributes to depth, width, and height adjustment of the backrest as well as angular adjustment of lateral supports to permit the backrest to conform to the anatomical shape of a user.  
         [0011]     The present invention is further directed towards a backrest foam assembly comprising foam having multiple sections that are adapted to be positioned or repositioned relative to each other and thereby vary the overall width of the foam. A cover also comprises multiple sections, each covering a foam section. The covered foam sections are adapted to be positioned or repositioned relative to each other to vary the overall width of the backrest foam assembly. The individual covers are adapted to interconnect to provide an aesthetic appearance for a complete backrest foam assembly.  
         [0012]     Moreover, the present invention is directed towards a multi-position adjustable armrest assembly. The armrest combines large-scale and small-scale adjustments, which provides a broad range of adjustment for the armrest and its position. The armrest has the capability of infinitesimal angle adjustment of the armrest pad and infinitesimal height adjustment of the armrest pad within a given height range.  
         [0013]     Additionally, the present invention is directed towards a power recline mechanism with programmable shear reduction. The mechanism includes a dual rotary mechanism.  
         [0014]     Lastly, the present invention is further directed towards a roller clutch bearing (i.e., a one-way bearing) that is sleek and attractive. The roller clutch bearing is a tight aesthetically pleasing functional device. The roller clutch bearing is particularly well suited for use with a leg rest mechanism.  
         [0015]     Various objects and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, when read in light of the accompanying drawings.  
     
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0016]      FIG. 1  is a rear perspective view of a seat assembly having a backrest according to one embodiment of the present invention.  
         [0017]      FIG. 2  is a rear perspective view of a seat assembly having a single-pivot reclining backrest according to another embodiment of the present invention.  
         [0018]      FIG. 3  is a rear perspective view of a seat assembly having a reclining backrest with shear reduction according to yet another embodiment of the present invention.  
         [0019]      FIG. 4  is a rear perspective view of a seat assembly having a reclining backrest with programmable shear according to still another embodiment of the present invention.  
         [0020]      FIG. 5  is a top plan view of a backrest according to the present invention with swing-away and non-swing-away lateral thoracic supports attached to the backrest.  
         [0021]      FIG. 6  is a top plan view of the backrest shown in  FIG. 5  with the swing lateral thoracic support swung away to the rear of the backrest.  
         [0022]      FIG. 7  is a top plan view of the backrest shown in  FIG. 5  with the lateral thoracic supports adjusted, for example, to conform to the natural anatomic shape (i.e., geometry) of a user.  
         [0023]      FIG. 8  is a front elevation view of the backrest shown in  FIG. 5 .  
         [0024]      FIG. 9  is a front elevation view of the backrest shown in  FIG. 7 .  
         [0025]      FIG. 10  is an enlarged scale rear perspective view of the swing-away lateral thoracic support shown in  FIGS. 5-8 .  
         [0026]      FIG. 11  is an exploded reduced scale rear perspective view of the swing-away lateral thoracic support shown in  FIG. 10 .  
         [0027]      FIG. 12  is an enlarged scale front perspective view of the non-swing-away lateral thoracic support shown in  FIGS. 5-8 .  
         [0028]      FIG. 13  is an exploded front perspective view of a backrest according to the present invention and a backrest foam assembly that is adjustable in width.  
         [0029]      FIG. 14  is a top plan view of the backrest foam assembly shown in  FIG. 13  in an initial position.  
         [0030]      FIG. 15  is a top plan view of the backrest foam assembly shown in  FIG. 13  wherein foam sections are outwardly displaced to increase the width of the backrest foam assembly.  
         [0031]      FIG. 16  is a rear perspective view of an adjustable armrest assembly according to the present invention.  
         [0032]      FIG. 17  is an exploded rear perspective view of the adjustable armrest assembly shown in  FIG. 16 .  
         [0033]      FIG. 18  is a partially exploded rear perspective view of the adjustable armrest assembly, depicting height adjustment capability using a rear mount.  
         [0034]      FIG. 19  is a side elevational view of the adjustable armrest assembly in a lowered position.  
         [0035]      FIG. 20  is a partial rear perspective view of the adjustable armrest assembly partially exploded to depict height adjustment steps and width adjustment capability using a mount rod.  
         [0036]      FIG. 21  is a side elevational view of the adjustable armrest assembly in a raised position.  
         [0037]      FIG. 22  is a side elevational view of the adjustable armrest assembly partially exploded to show an angle adjustment mechanism, and further depicting armrest pad depth adjustment capability.  
         [0038]      FIG. 23  is a side elevational view of the adjustable armrest assembly in an upwardly angled position.  
         [0039]      FIG. 24  is a side elevational view of the adjustable armrest assembly in a downwardly angled position.  
         [0040]      FIG. 25  is an exploded front perspective view of a dual rotary power recline mechanism according to the present invention.  
         [0041]      FIG. 26  is a side elevational view of the seat assembly shown in  FIG. 26 , wherein the backrest is non-reclined or at an angle 90 degrees relative to the seat.  
         [0042]      FIG. 27  is a side elevational view of the seat assembly shown in  FIG. 26 , wherein the backrest is in a reclined position at an angle 110 degrees relative to the seat.  
         [0043]      FIG. 28  is a side elevational view of the seat assembly shown in  FIG. 26 , wherein the backrest is in a reclined position at an angle 130 degrees relative to the seat.  
         [0044]      FIG. 29  is a side elevational view of the seat assembly shown in  FIG. 26 , wherein the backrest is in a reclined position at an angle 150 degrees relative to the seat.  
         [0045]      FIG. 30  is a side elevational view of the seat assembly shown in  FIG. 26 , wherein the backrest is in a reclined position at an angle 170 degrees relative to the seat.  
         [0046]      FIG. 31  is a front perspective view of leg rest assemblies according to the present invention.  
         [0047]      FIG. 32  is an enlarged exploded front perspective view of a roller clutch of a leg rest assembly shown in  FIG. 32 . 
     
    
     DETAILED DESCRIPTION  
       [0048]     Referring now to the drawings, there are illustrated in  FIGS. 1-4  seat assemblies for wheelchairs. The seat assemblies  110  are in the form of modular seating platforms that can be mounted on various power wheelchair bases (not shown). The seat assemblies  110  may comprise a seat  112  that may be adjustable in width and a backrest  114  that may be adjustable in width independently of the width adjustment of the seat  112 . In addition, the seat  112  may be adjustable in depth and the backrest  114  may be adjustable in height. As a consequence of these adjustments, the seat assemblies  110  can preferably accommodate a very wide range of users, including a fifth percentile female user (i.e., small user) and up to a ninety-fifth percentile male user (i.e., about 400 pound user). The seat assemblies  110  may further comprise a center frame  116  that is preferably continuous and that preferably has an architecture that supports both the seat  112  and the backrest  114 . Consequently, the seat assemblies  110  may have an integrated aesthetic appearance.  
         [0049]     In accordance with the present invention, the seat assemblies  110  may accommodate one or more electrical control devices, as well as peripheral devices (e.g., positioning devices, power and manual center-mount leg rests, power and manual lateral leg rests, reclining and non-reclining arm rests, etc.). Consequently, the seat assemblies  110  may have an architecture that accommodates one or more auxiliary devices, such as but not limited to a non-recline rotary actuator, a seat and backrest with an infinitely adjustable angle (shown in  FIG. 1 ), a low-cost single-pivot power recliner (shown in  FIG. 2 ), a dual-rotary recliner with shear reduction (shown in  FIG. 3 ), and/or a dual-rotary recliner with programmable shear reduction (shown in  FIG. 4 ).  
         [0050]     Continuing with reference to the drawings, the seat assemblies  110  will be described in greater detail. For example, the seat  112  may comprise a central main member  112   a , such as the pan shown, and one or more lateral members, such as the opposing lateral members or wings  112   b  shown, that may be joined to the main member  112   a  in any suitable manner or fashion. As shown in the drawings, the main member  112   a  may be provided with one or more holes  112   c . Similarly, the lateral members  112   b  may be provided with one or more holes and/or slots, such as a plurality of patterns of holes  112   d  and/or slots  112   e . The holes  112   d  and/or slots  12   e  in the lateral members  112   b  may be adapted to selectively align with one or more desired holes  112   c , or slots, in the main member  112   a  to permit one or more fasteners (not shown) to pass therethrough. The selective alignment may permit the width of the seat  112  to be adjusted as desired.  
         [0051]     The main member  112   a  may be supported from below by a first seat portion  116   a  of the center frame  116 . The first seat portion  116   a  may be slidably adjustable relative to a second seat portion  116   b ,  116   c  of the center frame  116 . This may permit the seat  112  to be adjusted relative to the back  114  and thus may permit the depth of the seat  112  to be adjusted. The first seat portion  116   a  of the center frame  116  may be secured in a fixed position relative to the second seat portion  116   b ,  116   c  of the center frame  116  in any suitable manner, such as by one or more fasteners (not shown), including but not limited to threaded fasteners.  
         [0052]     The backrest  114 , like the seat  112 , may comprise a central main member  114   a  and one or more lateral members, such as the opposing lateral members or wings  114   b  shown, that may be joined to the main member  114   a  in any suitable manner or fashion. As shown in the drawings, the main member  114   a  may be provided with a plurality of holes  114   c , or slots. The lateral members  114   b  may be provided with a plurality of holes or slots  114   d . The holes or slots  114   d  in the lateral members  114   b  may be adapted to selectively align with one or more desired holes or slots  114   c  in the main member  114   a  to permit one or more fasteners (not shown) to pass therethrough. The selective alignment may permit the width of the backrest  114  to be adjusted as desired.  
         [0053]     The main member  114   a  may be supported from behind by a backrest portion  116   d ,  116   e  of the center frame  116 . The main member  114   a  may be adjustable, for example, in a substantially vertical direction, relative to the backrest portion  116   d ,  116   e . This may permit the backrest  114  to be adjusted in height. The main member  114   a  of the backrest  114  may be secured in a fixed position relative to the backrest portion  116   d ,  116   e  of the center frame  116  in any suitable manner, such as by one or more fasteners (not shown), including but not limited to threaded fasteners.  
         [0054]     As shown in the drawings, the second seat portion  116   b ,  116   c  and the backrest portion  116   d ,  116   e  of the center frame  116  may be connected together by a rotary mechanism  174 , such as, for example, a Taumel 2000 Power rotary mechanism, manufactured by KEIPER Seat Components L.L.C., in Clawson, Mich., USA, which includes interacting stamped components that may connect the second seat portion  116   b ,  116   c  and the backrest portion  116   d ,  116   e.    
         [0055]     It is noted that the lateral members  112   b ,  114   b  may have a curved outer portion that may provide lateral support for the user of the seat assemblies. It should be appreciated that the invention is not intended to be limited to the particular features of the seat assemblies shown. For example, the main members  112   a ,  114   a  may be shaped differently then shown, or have different arrangements of holes or slots, or may be provided with grooves, tracks or other suitable positive or negative structure that permits adjustment of the lateral members  112   b ,  114   b . Similarly, the lateral members  112   b ,  114   b  may be shaped differently then shown, or have different arrangements of holes or slots, or may be provided with grooves, tracks or other suitable positive or negative structure that selectively mates with corresponding structure of the main members  112   a ,  114   a  to permit adjustment of the lateral members  112   b ,  114   b.    
         [0056]     Now, with reference to  FIGS. 5-12 , there are illustrated swing-away and non-swing-away lateral thoracic supports  118 ,  120  that may be adapted to be attached to the backrest  114 . The thoracic supports  118 ,  120  may be removably or releasably secured to one or more lateral members  114   b , which may be adjustable relative to a central main member  114   a  of the backrest  114 , as will be described below. The thoracic supports  118 ,  120  may be secured to the lateral members  114   b  in any suitable manner or fashion, including but not limited to the use of one or more threaded or other suitable fasteners  124 .  
         [0057]     One or more holes or slots  114   e , as shown in  FIGS. 8 and 9 , may be provided along outer portions of one or more or the lateral members  114   a  and may be adapted to receive one or more fasteners  124 . The holes or slots  114   e  may permit adjustment (e.g., up and down along the lines  126  in  FIG. 8 ) of the thoracic supports  118 ,  120 , for example, in a substantially vertical direction, relative to the lateral members  114   b . One or more backing plates  128 , or washers or the like, may be provided and the fasteners  124  may pass through the backing plates  128  and further through the holes or slots  114   e  for securing the thoracic supports  118 ,  120  to the lateral members  114   b . The backing plates  128  may improve the securement of the thoracic supports  118 ,  120  to the lateral members  114   b . Although slots  114   e  are shown, the invention is not intended to be limited to slots but may be practiced with other positive or negative structure, such as but not limited to holes, grooves or other suitable structure.  
         [0058]     The thoracic supports  118 ,  120  also may be adapted to be adjusted laterally (i.e., along the lines  130  in  FIG. 5 ) relative to the lateral members  114   b . This can be achieved in any suitable manner. For example, the thoracic supports  118 ,  120  can be provided with one or more lateral slots, such as the holes or slots  118   a ,  120   a  shown in  FIGS. 10-12 . These slots  118   a ,  120   a  may permit the thoracic supports  118 ,  120  to be laterally adjusted simply by, for example, loosening the fasteners  124 . In addition to being laterally adjustable, the slots  118   a ,  120   a  may permit angular adjustment (i.e., along the lines  132  in  FIG. 9 ) of the thoracic supports  118 ,  120 , as shown in  FIGS. 7 and 9 .  
         [0059]     The swing-away thoracic support  118 , unlike the non-swing-away thoracic support  120 , may have a hinge, generally indicated at  118   b  in  FIGS. 10 and 11 . The hinge  118   b  may permit the swing-away thoracic support  118  to be swung (i.e., along the line  134  in  FIG. 6 ) rearward of the backrest  114  and out of the way of the user. This can be accomplished in any suitable manner or fashion. For example, a latch lever  118   c  may be displaced (i.e., along the line  136  in  FIG. 10 ) from a locked position to unlock the hinge  118   b  and permit the swing-away thoracic support  118  to be swung, for example, rearward of the backrest  114 . The latch lever  118   c  may be biased back into the locked position to lock the hinge  118   b  and prevent the swing-away thoracic support  118  from being swung. It should be appreciated that the latch lever  118   c  may be biased automatically, for example, by a spring  118   d  or other suitable element, into the locked position.  
         [0060]     Now, further with reference to  FIGS. 13-15 , there is illustrated a width-adjustable backrest foam assembly  138  according to the present invention. The backrest foam assembly  138  may comprise a central main foam member  138   a  and one or more lateral foam members, such as the opposing lateral foam members  138   b  shown, that may be displaceable relative to the main foam member  138   a.    
         [0061]     The foam members  138   a ,  138   b  are preferably made of polyurethane, although the invention may be practiced with any suitable material. The main foam member  138   a  may be provided with one or more tapered regions and/or flange portions, such as the opposing tapered regions  138   c  and the opposing flange portions  138   d  shown. The lateral members  138   b  may be provided with one or more tapered regions  138   e  that may mate with corresponding tapered regions  138   c  of the main foam lateral member  138   a . The lateral members  138   b  may be displaceable to adjust. the width of the backrest foam assembly  138 . For example, from an initial position shown in  FIG. 14 , the lateral members  138   b  may be outwardly displaceable (i.e., along the lines  140  in  FIG. 15 ) to increase the width of the backrest foam assembly  138 .  
         [0062]     The backrest foam assembly  138  may further comprise one or more covers, such as the covers  138   f ,  138   g  shown about the foam members  138   a ,  138   b . The covers  138   f ,  138   g  are preferably made of a breathable material. The covers  138   f ,  138   g  may be secured about the foam members  138   a ,  138   b  in any suitable manner. For example, the covers  138   f ,  138   g  may be made of material cut to fit the form of the foam members  138   a ,  138   b  and stitched to form enclosures. The enclosures may be closed via one or more fasteners (not shown), such as slideable fasteners (i.e., zippers) or other suitable fasteners.  
         [0063]     The foam members  138   a ,  138   b  may be secured to the seat back and to each other in any suitable manner. For example, a first part  142  of a hook-and-loop type fastener may be attached to the flange portions  138   d  of the main foam member  138   a  and/or the front of the backrest  114 . A second part  144  of the hook-and-loop type fastener may be attached to the back and/or tapered regions  138   e  of the lateral foam members  138   b . The first part  142  may be matingly engageable with the second part to secure the foam members  138   a ,  138   b  to one another and to the backrest  114 . The parts  142 ,  144  of the hook-and-loop type fastener may be disengaged to permit the lateral foam members  138   b  to be displaced relative to the main foam member  138   a  to adjust the width of the foam assembly  138 .  
         [0064]     It should be appreciated that, since the foam assembly  138  may comprise multiple foam sections that may be adapted to be positioned or repositioned relative to each other and thereby vary the overall width of the foam assembly  138 , the foam assembly also may comprise multiple covers sections, each covering a foam section. The covered foam sections may be adapted to be positioned or repositioned relative to each other to vary the overall width of the foam assembly  138 . The individual covers may be adapted to interconnect to provide an aesthetic appearance for a complete foam assembly  138 . It should be appreciated that the foam assembly  138  is not limited to the assembly described and shown. For example, such an assembly may be similarly configured with foam sections that may be positioned or repositioned relative to each other to vary the overall height of the foam assembly. Similarly, multiple foam sections may be adapted to be positioned or repositioned relative to each other to vary the overall width or depth of an assembly that is suitable for use as a seat cushion.  
         [0065]     In  FIGS. 16 and 17 , there is illustrated an adjustable armrest assembly  146  according to the present invention. The armrest assembly  146  may comprise an armrest base  148  and armrest pad  150  that may be supported by the base  148 . The base  148  may be adapted to be secured to a backrest (not shown), for example, by a rear mount  152  and a mount rod  154 . The mount rod  154  may be engageable with a fine adjustment mechanism  156  (shown in  FIG. 17 ) that may be supported by the base  148 . The armrest assembly  146  may permit several adjustments, including, for example, height adjustment, width adjustment, armrest pad angle adjustment, and/or armrest pad depth adjustment. All of the adjustments that can be made are preferably infinitesimal in nature.  
         [0066]     As depicted in  FIG. 18 , the armrest assembly  146  may be adjustable in height via the rear mount  152 . This can be accomplished, for example, by loosening the rear mount  152  (e.g., via fasteners  152   a ) and sliding the rear mount  152  (i.e., along the line  158  in  FIG. 18 ), for example, in a substantially vertical direction relative to the backrest (not shown). The armrest assembly  146  also can be adjustable in height, for example, by removing the rear mount  152 , inverting the rear mount  152 , and then replacing the rear mount  152  on the backrest.  
         [0067]     The armrest assembly  146  also may be adjustable in height via the mount rod  154 . For example, the armrest assembly  146  is shown in a lowered position in  FIG. 19 . To raise the armrest assembly  146 , the rear mount  152  may be comprised of a clamp  152   b  that may be adapted to be loosened (e.g., via threaded fastener  152   c ). Upon loosening the clamp  152   b , the mount rod  154  can be slid out of the clamp  152   b  (i.e., in the direction of arrow  162  in  FIG. 20 ). The mount rod  154  can then be rotated (i.e., along the line  164  in  FIG. 20 ) until the armrest assembly  146  is at a desired height. Once at a desired height, the mount rod  154  can be slid back into the clamp (i.e., in the direction of arrow  166  in  FIG. 20 ) and the clamp can tightened accordingly. In  FIG. 21 , the armrest assembly  146  is secured in a raised position.  
         [0068]     The armrest assembly  146  is preferably incrementally adjustable in height by providing, for example, indexing flats  154   a  (shown in  FIG. 20 ) on the mount rod  154 . Infinite height adjustment (i.e., fine tuning) in the armrest assembly  146 , within a given height range, may be accomplished by, for example, loosening the threaded fasteners  152   a  and moving the rear mount  152 . The indexing flats  154   a  on the mount rod  154  and the movement of the rear mount  152  may permit the armrest pad  150  to be placed at substantially any angle, or at a wide range of angles, in an X-Y plane.  
         [0069]     As depicted in  FIG. 18 , the armrest assembly  146  may be adjustable in width inward and outward (i.e., along the line  168  in  FIG. 18 ), for example, at the interface of the rear mount  152  and the mount rod  154 . Also, the armrest pad  150  can be, for example, rotated (i.e., along the line  170 ) to provided additional width adjustment.  
         [0070]     The angle adjustment of the armrest assembly  146  may be best understood with reference to  FIGS. 22-24 .  FIG. 22 , in particular, shows the fine adjustment mechanism  156 , which may include a clamp  156   a , which can be loosened, for example, by loosening a fastener, such as the threaded fastener  156   b  shown. Upon loosening the clamp  156   a , the armrest base  148  can be rotated relative to the mount rod  154  within the clamp  156   a . The base  148  can be rotated up to angle the base  148  upward, as shown, for example, in  FIG. 23 , and down to angle the base  148  downward, as shown, for example, in  FIG. 24 . With the armrest base  148  at the desired angle, the threaded fastener  156   b  can be tightened to tighten the clamp  156   a  about the mount rod  154  and thus secure the armrest base  148  in place. It should be understood that the mount rod  154  can include, for example, indexing flats (not shown), as shown on the opposite end of the mount rod  154 . Also, a secondary clamp  156   c  may be provided, which can be tightened, for example, via a fastener, such as the threaded fastener  156   d  shown, to remove slop in the armrest assembly  146 . Further, the angle of the base  148  can be fine tuned by, for example, a fastener, such as the threaded fastener  156   e  shown.  
         [0071]     The armrest pad  150  also may have a depth adjustment capability. The adjustment of the depth of the armrest pad  150  can be achieved, for example, by loosening one or more fasteners, such as threaded fasteners (not shown), sliding the armrest pad  150  (i.e., left or right along the line  172  when viewing  FIG. 22 ) to a desired depth, and then tightening the fasteners.  
         [0072]     The adjustable armrest assembly  146  according to the invention combines four adjustment features without limiting those adjustments to pre-set increments. The new armrest assembly  146  has a capacity for positioning the armrest pad  150  where it is needed for maximum benefit to the user.  
         [0073]     Referring back to  FIG. 1 , there is illustrated a seat assembly according to one embodiment of the invention. This seat assembly may include one or more single rotary mechanisms, such as the single rotary mechanism  174  on the opposing seat portions  116   b  of the center frame  116 . A shaft  176  may be splined to mate with the rotary mechanisms  174 . A tool-engaging portion  176   a  may be provided on at least one end of the shaft  176 . The tool or knob (not shown) may engage the tool engaging portion  176   a , and may be rotated to operate the rotary mechanism  174  to recline the backrest  114 . Though the rotary mechanisms  174  are manually controlled, the seat assembly may include one or more actuators  178  and more or more controllers  180  for operating peripheral devices (not shown). This seat assembly may include shroud members  182   a ,  182   b  that provide a pleasing aesthetic appearance for the seat assembly.  
         [0074]     In  FIG. 2 , there is illustrated a single-pivot reclining seat assembly, wherein a motor  184  is supported at each end of the shaft  176 . The motors  184 , in turn, are mounted between the rotary mechanisms  174  and the backrest portion  116   d  of the center frame  116 . The motors  184  may be controlled to operate the rotary mechanisms  174  to recline the backrest  114 . The seat assembly may include one or more actuators  178  and controllers  180  for operating the rotary mechanisms  174  and other the peripheral devices (not shown), and may include shroud members  182   a ,  182   b  that provide a pleasing aesthetic appearance for the seat assembly.  
         [0075]     In  FIG. 3 , there is illustrated a reclining seat assembly with shear reduction. The shear reduction is achieved through the use of one or more dual rotary recline mechanisms  186 . In accordance with the present invention, recline mechanisms  186  are supported by opposing sides of the second seat portion  116   c  of the center frame  116 . A shaft  176  may extend between the recline mechanisms  186 . A motor  184  may be supported at each end of a shaft  176 . The motors  184 , in turn, may be mounted between the recline mechanisms  186  and the backrest portion  116   e  of the center frame  116 . The motors  184  may be controlled to operate the recline mechanisms  186  to recline the backrest  114 . The seat assembly may include one or more actuators  178  and controllers  180  for operating the recline mechanisms  186  and optionally other the peripheral devices (not shown), and may include shroud members  182   c ,  182   d  that provide a pleasing aesthetic appearance for the seat assembly.  
         [0076]     It should be noted that a gas spring  190  may be connected between the second seat portion  116   c  of the center frame  116  and the backrest portion  116   e  of the center frame  116 . The gas spring  190  may be slidably connected to a bracket  192 , which in turn may be attached to the backrest portion  116   e  of the center frame  116 . As the backrest  114  reclines, the gas spring  190  may slide along the bracket  192  until an upper end of the gas spring  190  engages a lip at the top of the bracket  192 . When the upper end of the gas spring  190  engages the lip at the top of the bracket  192 , which preferably occurs when the backrest  114  has reclined at an angle of about 130 degrees relative to the seat  112 , the gas spring  190  begins to compress. This reduces the load on the motors  184 .  
         [0077]     In  FIG. 4 , there is illustrated a reclining seat assembly with programmable shear reduction. This seat assembly is similar to that shown in  FIG. 3  and described above in that the seat assembly includes one or more dual rotary recline mechanisms  186 , corresponding motors  184  for controlling the operation of the recline mechanisms  186 , and a gas spring  190  for reducing the load on the motors  184 . Further in accordance with the present invention, this seat assembly may comprise a linear actuator  194  connected between the second seat portion  116   c  of the center frame  116  and the backrest portion  116   e  of the center frame  116 , or is otherwise connected to the backrest. In addition, the seat assembly may comprise a pair of tracks  196  or other suitable structure upon which the backrest  114  can travel. The linear actuator  194  may be controlled by a controller  188  to move the backrest along the tracks  196  to substantially eliminate any shear that is not addressed by the dual rotary recline mechanisms  186  as the backrest is moved between tilted and non-tilted positions, or vice versa.  
         [0078]     Now, with reference to  FIG. 25 , a dual rotary recline mechanisms  186  according to one embodiment of the invention will be described. The dual rotary power recline mechanism  186  may comprise two rotary recline mechanisms  186   a ,  186   b  engaging one another. The recline mechanisms  186   a ,  186   b  may be joined together in any suitable manner. In the illustrated embodiment of the invention, fasteners  198  join the recline mechanisms  186   a ,  186   b  together. The same fasteners  198  may attach a pulley plate  200  to the recline mechanisms  186   a ,  186   b . Bearings  210  may be supported relative to the pulley plate  200 , such as by being pressed into the pulley plate  200 . Female splined shafts  212  may be passed through the bearings  210 . Shaft locks  214  may be carried by the female splined shafts  212 . Drive and idler pulleys  216 ,  218  may be locked to corresponding female splined shafts  212  by the shaft locks  214 . A tensioner  220  may be pivotally supported relative to the pulley plate  200  and may carry tension bearings or pulleys  222 . The drive and idler pulleys  216 ,  218  may carry a belt  224 , and the tension pulleys  222  may keep tension on the belt  224  via one or more springs  226 , which may be connected between the pulley plate  200  and the tensioner  220 . A motor  184  may be connected to the dual rotary power recline mechanism  186 , opposite the pulley plate  200 , via, for example, a motor mount  228 . A male splined drive shaft  230  may engage the female splined shaft  212  supporting the drive pulley  216 . A male splined idler shaft  232  may engage the female splined shaft  212  supporting the idler pulley  218 . The male splined drive shaft  230  may have a spud  234  on its end that engages a flex coupling  236  on the shaft  176 , which may extend between the dual rotary recline mechanisms  186  on opposing sides of the seat portion of the center frame (not shown).  
         [0079]     In operation, the motors  184  may drive the male splined drive shafts  230 , which may drive a first one of the two rotary recline mechanisms  186   a , while driving the drive pulley  216 . The drive pulley, in turn, may drive the idler pulley  218 , which may drive the male splined idler shaft  234 , which in turn may drive a second one of the two rotary recline mechanisms  186   b . It should be noted that the belt  224  may cause the idler pulley  218  to be driven in a direction opposite that of the drive pulley  216 . This may cause the second rotary recline mechanism  186   b  to be driven in a direction opposite that of the first rotary recline mechanism  186   a . It should also be noted that the idler pulley  218  may be larger than the drive pulley  216 . In the illustrated embodiment, the idler pulley  218  is twice the size of the drive pulley  216 , thus producing a 2:1 ration between the idler pulley  218  and the drive pulley  216 . This ratio may vary depending on the desire operation profile for the reclining seat assembly. This ratio may affect the rate that the backrest (not shown) reclines. It should be appreciated that the belt  224  can be omitted and both recline mechanisms  186   a ,  186   b  may be driven independently by separate motor (not shown).  
         [0080]     The operation of the dual rotary recline mechanisms  186  is illustrated in  FIGS. 26-30 . As the drive pulley  216  is driven clock wise, the idler pulley  218  is driven counter-clockwise. Due to the 2:1 ratio between the pulleys  216 ,  218 , the idler pulley  218  is driven twice as fast as the drive pulley  216 . Consequently, the motors  184  can operate at a reduced rate to achieve a desired rate of recline.  
         [0081]     It should be appreciated that the dual rotary recline mechanism shown in  FIG. 25  and described above is only provided for illustrative purposes and that the invention can be practiced with configurations other than that shown and described. The operation of the dual rotary recline mechanisms  186  is illustrated in  FIGS. 26-30 . In a general context, the invention may be practiced via any configuration suitable for producing a rotary movement in a first or clock wise direction coupled which a configuration suitable for producing a rotary movement in an opposite, or second or counter-clock wise, direction. That is to say, a first rotary configuration may support for orbital movement a second rotary configuration that rotates in a direction opposite its orbital travel. In essence, the invention may be broadly practiced with a rotary configuration that moves or travels along a curved or arcuate path and that rotates, preferably simultaneously, in a direction opposite its curved or arcuate travel.  
         [0082]     Finally, with reference to  FIG. 31 , there is illustrated a pair of leg rest assemblies  240  according to the present invention. The leg rest assemblies  240  may be adapted to be attached to the center frame (not shown) of the seat assembly. The leg rest assemblies  240  may include leg rests  240   a  that are free to rotate up (i.e., along the line  242  in  FIG. 31 ).  
         [0083]     As shown in  FIG. 32 , the leg rest assemblies  240  may include a roller-clutch  244  that rolls free in one direction, locking on a ring shaft  246  of a fixed diameter. A housing  248  may be attached to the roller-clutch  244  via a spring-loaded ring  250 . The ring  250  may be adapted to slide axially in-and-out of engagement of the roller-clutch  244 . While engaged, the roller-clutch  244  can only rotate in a first direction. Pushing on a push button  252  (and holding the button  252  in place) may slide the ring  250  axially out of engagement with the roller-clutch  244 . This may allow the housing  248  to rotate back down. When the button  252  is released, the ring  250  may be pushed back into engagement with the roller-clutch  244 , which will again only allow rotation of the roller-clutch  244  in the first direction.  
         [0084]     The roller-clutch  244  is preferably a unidirectional mechanism that functions to replace conventional large cam locking assemblies. The spring-loaded ring  250  is a release mechanism that allows push button engagement and disengagement of the roller-clutch  244 .  
         [0085]     The roller-clutch  244  is not intended to be limited in its application to the leg rest assembly, as described above, but instead has other applications, such as but not limited to a swing-away latch, a backrest, a flip-back armrest, and “grade aids”.  
         [0086]     The principle and mode of operation of this invention have been explained and illustrated in its preferred embodiment. However, it must be understood that this invention may be practiced otherwise than as specifically explained and illustrated without departing from its spirit or scope.