Abstract:
The present automatic wheelchair brake device invention includes a brake mechanism adapted to be installed on an existing collapsible wheelchair. The brake mechanism may be adapted to be operably installed on only one side of a frame of the collapsible wheelchair such that a side-to-side collapsibility of the frame of the collapsible wheelchair is significantly unimpeded by the brake mechanism. The brake mechanism may be movable between an engaged position that generally inhibits rolling movement of the wheelchair and a disengaged position permitting free rolling movement of the wheelchair in response to movement of structure on the one side of the frame of the collapsible wheel chair between a first position when the wheelchair is occupied and a second position when the wheelchair is unoccupied.

Description:
PRIORITY  
       [0001]     This application claims the benefit of provisional patent application Ser. No. 60/602,125 filed on Aug. 17, 2004, and provisional patent application Ser. No. 60/567,907 filed on May 4, 2004, both of which are incorporated herein by reference in their entirety. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The invention generally relates to braking devices for wheelchairs. More particularly, the invention relates to an automatic wheelchair brake device weight-actuated brake mechanism for wheelchairs that is automatically actuated depending upon the position of the user with respect to the wheelchair.  
       BACKGROUND OF THE INVENTION  
       [0003]     A conventional manual wheelchair is illustrated in  FIGS. 1 and 2 . Conventional manual wheelchairs  50  typically comprise a foldable frame  52 , a seat  54  and a backrest  56 , and a pair of manual brake mechanisms  58   a  and  58   b.  Two large drive wheels  60   a  and  60   b  are typically rotatably mounted to the foldable frame  52  to permit a user to operate and move the wheelchair. The manually operated hand brakes  58   a  and  58   b  are coupled to the wheelchair to engage and prevent rotational movement of the drive wheels. Conventional wheelchairs  50  also typically include leg rests  62  and armrests  64  for the comfort of the user.  
         [0004]     The manual brake mechanisms  58   a  and  58   b  allow either a user or an attendant to lock the wheels of the wheelchair when exiting, for example, so that the chair does not move away when a patient attempts to enter or exit. Although the conventional manual brake mechanisms are sufficient for their intended purpose once engaged, the requirement that the user must remember to actuate the brakes leaves these devices susceptible to user error. For example, a conventional wheelchair will remain freely moveable if a user or attendant forgets to manually pivot the braking device and lock the wheels. The wheelchair may also remain freely moveable if a user or attendant does not fully apply the manual braking device to the wheels. As a result, a user attempting to stabilize himself or herself while entering or leaving the wheelchair, is at an increased risk of falling and injury due to the freely moveable wheelchair moving out from beneath them.  
         [0005]     Attempts have been made to devise wheelchair-braking devices that automatically engage a wheel of a wheelchair when a user attempts to enter or leave the seat. For example, U.S. Pat. No. 5,894,912 to Dobben includes a sensing lever that senses when a user is entering or leaving the seat of a wheelchair. When the sensing lever senses a user exiting the seat it causes a braking lever to engage the wheels, thereby preventing free movement of the wheelchair. While the design of the wheelchair-braking device in Dobben fulfills its intended purpose, it has at least one significant shortcoming. In particular, the sensing lever, disposed beneath the seat, is continuously biased against a seated user. The continuously biased state of the sensing lever creates uncomfortable pressure points that are continuously felt by the seated user. These pressure points may additionally promote development of sores by the patient.  
         [0006]     Another attempt at devising an automatic braking-device for a wheelchair is illustrated in U.S. Pat. No. 6,371,503 to Ritchie, et al. Ritchie discloses an L-shaped actuator that confronts a rear portion of the seat of a wheelchair. When a user sits in the wheelchair the seat engages the L-shaped actuator, which releases the braking-device. The actuator continues to press against the seated user until they exit the wheelchair. The automatic braking-device of Ritchie is susceptible to the same shortcomings as Dobben discussed above. In particular, the constant pressure by the actuator on the seated user creates a pressure point.  
         [0007]     Other attempts to invent automatic braking-devices for wheelchairs have resulted in undesirably complicated braking assemblies. For example, U.S. Pat. No. 4,620,818 to Knoche, discloses a wheelchair having a sliding side frame that engages a pair of brake arms pivotally coupled to the wheelchair. The brake arms engage the wheels of the wheelchair as a user sits in the seat. Not only is the automatic braking assembly disclosed in Knoche overly-complicated, it also requires a user to modify the wheelchair&#39;s existing brake system. In particular, each of the brake arms includes a transverse portion that replaces the conventional manual wheelchair device. As a result, the modified wheelchair has only one braking device. Additionally, modifying the wheelchair in order to attach the transverse portion of the braking assembly may result in voiding the warranty of the wheelchair.  
         [0008]     Still other attempts to resolve the problem associated with conventional wheelchair braking systems have resulted in modified wheelchair frames. For example, U.S. Pat. No. 5,984,334 to Dugas discloses a wheelchair with a moveable seat operationally coupled to a braking mechanism that locks one or more wheels when a user attempts to exit the seat. Another example of a modified device is U.S. Pat. No. 5,451,193 to Pickard. Pickard discloses a new wheelchair having four wheels of the same size. Additionally, the Pickard wheelchair is convertible to a walker. The custom nature of the Dugas and Pickard wheelchairs results in higher manufacturing costs, which are typically passed on to the consumer resulting in a more expensive wheelchair.  
         [0009]     Another disadvantage with the previous attempts to provide automatic brake devices to a wheelchair is that the brake devices disable the manual wheelchair&#39;s ability to fold for storage or transport.  
         [0010]     There remains a need in the wheelchair industry to provide an automatic braking mechanism that intervenes and prevents injuries caused by a freely movable wheelchair rolling out beneath a user as they attempt to enter or leave the seat portion, while addressing manufacturing, operability, cost and functional design issues.  
       SUMMARY OF THE INVENTION  
       [0011]     The present invention, through various embodiments, provides an automatic wheelchair brake device that addresses the deficiencies of the prior art attempts to provide a wheelchair with automatically applying brakes. In particular embodiments as will be described herein, the automatic wheelchair brake device is generally easily retrofittable to an existing wheelchair frame. The ease of retrofitability is enhanced by configuring the brake device to use existing fastening points on the wheelchairs&#39; frame. The mechanism to sense when a patient sits in the chair, thereby causing the brakes to release, is designed to not present pressure points to the patient. In addition, the wheelchair&#39;s normal folding operation is preserved. Brake mechanism operate independently of each other when applied to each side of a wheelchair. The brake device of the present invention may also be manufactured for a minimum of cost compared to automatic brake designs in the prior art.  
         [0012]     The present automatic wheelchair brake device invention according to particular embodiments includes a brake mechanism adapted to be installed on an existing collapsible wheelchair. The brake mechanism may be adapted to be operably installed on only one side of a frame of the collapsible wheelchair such that a side-to-side collapsibility of the frame of the collapsible wheelchair is significantly unimpeded by the brake mechanism. The brake mechanism may be movable between an engaged position that generally inhibits rolling movement of the wheelchair and a disengaged position permitting free rolling movement of the wheelchair in response to movement of structure on the one side of the frame of the collapsible wheel chair between a first position when the wheelchair is occupied and a second position when the wheelchair is unoccupied.  
         [0013]     The automatic wheelchair brake device according to another embodiment includes a brake mechanism movable between an engaged position that generally inhibits movement of a wheel of a wheelchair when unoccupied and a disengaged position permitting free movement of the existing wheelchair when occupied. The brake device may further comprise a seat engagement assembly operable coupled to the brake mechanism, the seat engagement assembly configured to be generally free from creation of pressure points on an occupant of the wheelchair.  
         [0014]     Another embodiment of the present invention includes a method of automatically applying brakes on a wheelchair without imparing the foldability of the wheelchair or presenting pressure points on an occupant of the wheelchair. This method may include providing a brake mechanism to a frame of a wheelchair, biasing the brake mechanism in an unoccupied position when the wheelchair is unoccupied wherein a wheel of the wheelchair is generally restrained from rotating when the chair is unoccupied, and contacting a frame of the wheelchair proximate a seat of the wheelchair when a patient sits in the wheelchair, thereby moving the brake mechanism to an occupied position, wherein the wheel generally unrestrained from rotating.  
         [0015]     The above summary of the present invention is not intended to describe each illustrated embodiment or every implementation of the present invention. The following figures and detailed description more particularly exemplify the embodiments of the present invention. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]     The invention may be more completely understood in consideration of the following detailed description of various embodiments of the invention in connection with accompanying figures, in which:  
         [0017]      FIG. 1  is a perspective view of a conventional manual wheelchair with manually operated brake mechanism.  
         [0018]      FIG. 2  is a front view of a conventional manual wheelchair with manually operated brake mechanism.  
         [0019]      FIG. 3  is a rear view of a wheelchair brake mechanism according to an example embodiment of the present invention  
         [0020]      FIG. 4  is a partial exploded rear view of a wheelchair brake mechanism according to an example embodiment of the present invention.  
         [0021]      FIG. 5A  is a side view of a wheelchair brake mechanism in an engaged position according to an example embodiment of the present invention.  
         [0022]      FIG. 5B  is a side view of a wheelchair brake mechanism in a disengaged position according to an example embodiment of the present invention.  
         [0023]      FIG. 5C  is a side view of a wheelchair brake mechanism in an engaged position and showing how portions of said mechanism move to a disengaged position according to an example embodiment of the present invention.  
         [0024]      FIG. 6A  is rear partial cross section view of a wheelchair brake mechanism in an engaged position according to an example embodiment of the present invention.  
         [0025]      FIG. 6B  is rear partial cross section view of a wheelchair brake mechanism in an engaged position and showing how portions of said mechanism move to a disengaged position according to an example embodiment of the present invention.  
         [0026]      FIG. 6C  is a side view of a wheelchair brake mechanism in an engaged position showing how portions of said mechanism move to a disengaged position according to an example embodiment of the present invention.  
         [0027]      FIG. 7  is an enlarged view of  FIG. 6A  according to an example embodiment of the present invention.  
         [0028]      FIG. 8A  is a side view of another embodiment of a wheelchair brake mechanism in a disengaged position according to an example embodiment of the present invention.  
         [0029]      FIG. 8B  is a side view of another embodiment of a wheelchair brake mechanism in an engaged position according to an example embodiment of the present invention.  
         [0030]      FIG. 9  is a side view of an attendant controlled brake release assembly of a wheelchair brake mechanism according to an example embodiment of the present invention.  
         [0031]      FIG. 10A  is an end view of an attendant brake release assembly of a wheelchair brake mechanism according to an example embodiment of the present invention.  
         [0032]      FIG. 10B  is a cross section view of an attendant brake release assembly of a wheelchair brake mechanism according to an example embodiment of the present invention.  
         [0033]      FIG. 10C  is a side view of an attendant brake release assembly of a wheelchair brake mechanism according to an example embodiment of the present invention.  
         [0034]      FIG. 11  is a side view of a wheelchair brake mechanism according to an example embodiment of the present invention.  
         [0035]      FIG. 12  is a side view of a wheelchair brake mechanism according to an example embodiment of the present invention.  
         [0036]      FIG. 13  is a rear view of a wheelchair brake mechanism according to an example embodiment of the present invention.  
         [0037]      FIG. 14  is a top view of a wheelchair brake mechanism according to an example embodiment of the present invention.  
         [0038]      FIG. 15  is an enlarged view of a portion of  FIG. 13 .  
         [0039]      FIG. 16  is a side view of an attendant break release assembly and a friction brake assembly according to an example embodiment of the present invention.  
         [0040]      FIG. 17  is a side view of an attendant break release assembly and a friction brake assembly according to an example embodiment of the present invention.  
         [0041]      FIG. 18  is an end view of an attendant break release assembly and a friction brake assembly according to an example embodiment of the present invention. 
     
    
       [0042]     While the present invention is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit the invention to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.  
       DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0043]      FIGS. 3-18  collectively illustrate a wheelchair with a weight-actuated brake mechanism, indicated by numeral  100 , to control the free movement of the wheelchair. Referring generally to  FIGS. 3-5C , and particularly to  FIGS. 3 and 4 , typically two wheelchair brake mechanisms  100   a  (in an exploded view) and  100   b  are attached to a wheelchair  102 . Each wheelchair brake mechanism  100   a  and  100   b  controls the rotational movement of each of drive wheels  110   a  and  110   b  respectively. The following description of the wheelchair brake mechanisms  100   a  and  100   b  will be discussed singularly, but it should be noted that it applies equally to both mechanisms  100   a  and  100   b.    
         [0044]     The wheelchair brake mechanism  100   a  includes at least one support structure  200  comprising an elongate bar that is pivotally coupled to a portion of the foldable frame  108 . Although an elongate bar is shown and discussed as one of the example embodiments, it should also be noted that the support structure  200  may also comprise a rod or other similar component. The support structure  200  is preferably disposed generally between a respective drive wheel  110   a,    110   b  and the foldable frame  108 . At least a portion of the support structure  200  is disposed generally proximate the drive wheel  110   a,  such that it may engage the drive wheel  110   a  and prevent rotational movement thereof as a user enters or leaves the seat  104 .  
         [0045]     Referring to  FIGS. 4, 5A ,  5 B and  5 C, the support structure  200  includes first  202  and second  204  opposed ends. Referring to  FIGS. 3 and 4 , the support structure  200  is pivotally couplable to a support bracket  210  that is mountable to a portion of the foldable frame  108  of the wheelchair. In an example embodiment, the support bracket  210  is disposed on a rear portion of the foldable frame  108  defining the backrest of the wheelchair  106 . The support bracket  210  is disposed generally proximate a juncture between the backrest  106  and the seat  104  (shown in  FIG. 6A ). The support bracket  210  includes a plate portion  212  that is mountable to the foldable frame  108  with at least one fastener  214 , such as a screw, bolt, or like device. Fastener  214  preferably replaces existing fasteners fastened to the wheelchair  102 . By using the pre-existing mounting holes or fastening points on an existing wheelchair, the present invention is easily and quickly retro-fittable to variety of wheelchairs without the need to make modifications such as drilling holes.  
         [0046]     In one example embodiment, plate portion  212  may have a generally arcuate or curved shape to accommodate the foldable frame  108  of the wheelchair  102 . The support bracket  210  also includes a flange portion  216  traversing away from an outer surface of the plate portion  212 . A fastener  218  and coupler  219  pivotally couples the support structure  200  to the flange portion  216  of the support bracket  210 . Any fastener may be used, such as a bolt and nut that would permit pivotal movement between the support structure  200  and the flange portion  216 .  
         [0047]     To facilitate locking and unlocking the drive wheels  110   a  and  110   b  of the wheelchair  102 , the support structure  200  includes at least one braking lever  250  and at least one sensing lever assembly  300  extending away from the first  202  and second  204  ends respectively. Only one brake mechanism  100   a  or  100   b  is necessary to accomplish the desired braking function of the wheelchair  102 . However, it is most common to pair a first  100   a  and a second  100   b  braking mechanism with the opposing wheels  110   a  and  110   b.  It should be noted that the operation of braking mechanism  100   a  is separate and not dependant on operation of braking mechanism  100   b,  and vise-versa. The independent operation is facilitated, in part, by each brake mechanism  100   a  and  100   b  having its own respective sensing lever assembly  300 .  
         [0048]     The braking assembly has a default engaged position, as illustrated in  FIG. 5A , and disengaged position, as illustrated in  FIG. 5B .  FIG. 5C  shows the engaged position with the disengaged position superimposed along with directional arrows indicating the direction of movement of the indicated components. In the engaged position, braking lever  250  is disposed adjacent to and confronts a portion of the drive wheel  110   a  preventing it from rotating freely. In the disengaged position, the braking lever  250  is disposed sufficient distance away from the drive wheel  110   a  to allow it to freely rotate. Sensing lever assembly  300  facilitates rotational movement or pivoting of the support structure  200  from the engaged position toward the disengaged position when a user is entering or leaving the wheelchair  102 .  
         [0049]     Referring back to  FIGS. 3 and 4 , braking lever  250  traverses away from the support structure  200  and extends generally toward the drive wheel  110   a.  In one example embodiment, the braking lever  250  extends away from the support structure  200  at generally a ninety-degree angle, such that the support structure  200  has a generally L-shape. Other angles and shapes such as C-shaped, J-shaped, S-shaped and other similar shapes are also envisioned to be within the spirit and scope of the invention. In one example embodiment of the invention, the braking lever  250  is integral to the support structure  200 . In other embodiments of the invention the braking lever  250  may be detachably coupled to the support structure  200  to permit modification according to the wheelchair  102  being outfitted with the brake mechanism  100   a.    
         [0050]     Braking lever  250  comprises a generally rectangular plate or bar having a length generally greater than a width of the drive wheel  110   a.  The braking lever  250  also has an upper peripheral edge portion  252  and a lower peripheral edge portion  254 . The lower peripheral edge portion  254  engages or confronts the drive wheel  110   a  when the support structure  200  is in the engaged position. In an example embodiment, the lower peripheral edge portion  254  is generally linear however; it may also have a generally curvilinear or arcuate shape such that it mimics the arcuate shape of the drive wheel  110   a.  The generally arcuate shape provides more surface contact between the braking lever  250  and the drive wheel  110   a,  thereby increasing rotational resistance.  
         [0051]     Continuing with  FIGS. 3-5C , the brake mechanisms  100   a  and  100   b  include a biasing or tension member  260  such as a coiled spring or adjustable elastomeric strap that is coupled to and extends generally between either the support structure  200  and a portion of the foldable frame  108  or between the braking lever  250  and a portion of the foldable frame  108 . The biasing member  260  maintains support structure  200  in the default engaged position, as illustrated in  FIG. 5A , when a user is not seated in the seat  104  of the wheelchair  102 . By having the engaged position as the default position, the drive wheels  110   a  and  110   b  remain locked when the user is not seated, thereby immobilizing the wheelchair  102  and providing a stable structure for the user. Since the wheelchair  102  is immobilized, a user entering or leaving the seat  104  of the wheelchair  102  will have a significantly reduced chance of falling due to the wheelchair  102  coming out from under them.  
         [0052]     Referring back to  FIGS. 3 and 4 , the biasing member  260  includes a first end  262  and a second end  264 . The first end  262  is detachably coupled to either the braking lever  250  or the support structure  200 . In one example embodiment, the second end  264  is detachably coupled to a portion of the foldable frame  108  such as illustrated in  FIG. 3 . In this example embodiment, the second end  264  of the biasing member  260  includes a hook or S-shape hook member  265  attached thereto to facilitate detachable coupling of the biasing member  260  to a portion of the foldable frame  108 . The second end  264  of the biasing member  260  may be detachably coupled to a portion of the axle assembly  275  of the drive wheel  110   a  extending through a portion of the foldable frame  108  and secured thereto by a coupler  276  such as a nut or similar component. However, the second end  264  of the biasing member  260  may be attached anyplace on the wheelchair  102  that facilitates its ability to maintain the support structure  200  in the engaged position.  
         [0053]     In other example embodiments of the invention, the second end  264  of the biasing member  260  is coupled to an adjustable coupler  270  that is coupled to a portion of the foldable frame  108  to permit a user to adjust its length and thereby the tension that the biasing member  260  exerts upon the support structure  200 . In one example embodiment of the invention, as illustrated in  FIG. 4 , the adjustable coupler  270  may include a turnbuckle portion  272  and a threaded eyelet or hook portion  274 . Rotation of the threaded eyelet portion  274  in a clockwise direction shortens the length of the adjustable coupler  270 , thereby requiring the biasing member  260  to be stretched in order for the threaded eyelet portion  274  to be coupled to the foldable frame  108 .  
         [0054]     In another example embodiment, the biasing member  260  comprises an elongate generally elastomeric strap  260  having a plurality of spaced apertures or holes extending along a length thereof. In this example embodiment, adjustment is accomplished by changing the engagement point of the S-shaped hook  265  (or similar engagement device) to different apertures provided in the elastomeric strap. Other types of adjustable couplers  270  are also contemplated and considered to be within the spirit and scope of the present invention.  
         [0055]     As the user is seated, the support structure  200  moves from the engaged position to the disengaged position. Returning to  FIGS. 5A  though  5 C, the sensing lever assembly  300  is operably coupled to the support structure  200  and positionable beneath the seat  104  to sense when a user is entering or leaving the wheelchair  102 . In one example embodiment, as a user enters the wheelchair  102  the seat  104  travels in a downward vertical direction until it confronts and vertically displaces the sensing lever assembly  300 . The downward movement of the sensing lever  300  assembly causes the support structure  200  to pivot or rotate from the engaged position toward the disengaged position. In the engaged position, the drive wheel  110   a  is locked and not freely rotatable. With the user is seated, the support structure  200  in the disengaged position and the wheelchair  102  is freely moveable.  
         [0056]     Various configurations are contemplated for actuating the sensing lever assembly  300 . In one example embodiment, as illustrated in  FIGS. 6A, 6B ,  6 C and  7 , the sensing lever assembly  300  comprises a sensor bracket  310  having leg portion  312  pivotally coupled to the support structure  200  and a foot portion  314  transversely extending therefrom that is in operable communication with the seat  104  of the wheelchair  102 . The leg portion  312  is generally vertically or perpendicularly oriented with respect to a longitudinal axis of the support structure  200 . The foot portion  314  is oriented at a generally ninety degree angle with respect to the leg portion  312  such that the sensor bracket  310  has a generally L-shape. However, other shapes are also contemplated for the sensor bracket  310 , including but not limited to C-shaped, U-shaped, and J-shaped. Regardless of the shape utilized, the sensor bracket  310  is oriented such that the foot portion  314  extends generally beneath a portion of the foldable frame  108  defining the seat  104  of the wheelchair  102 .  
         [0057]     Depending upon the weight of the user, it may be advantageous to be able to adjust the distance between the seat  104  of the wheelchair  102  and the foot portion  314 . For example, a smaller user weighing less may need to decrease the distance to facilitate the seat  104  of the wheelchair  102  engaging the foot portion  314 . A larger user weighing more may increase the distance to permit the user to become fully seated in the wheelchair  102  before the support structure  200  moves from the engaged position to the disengaged position.  
         [0058]     In one example embodiment of the invention, as illustrated in  FIGS. 6A, 6B ,  6 C and  7 , a seat engagement assembly  350  is operably disposed on the foot portion  314  to facilitate adjustment of the distance between the seat  104  of the wheelchair  102  and the foot portion  314 . As particularly illustrated in the example embodiment of  FIG. 7 , the seat engagement assembly  350  comprises a stop  352  having a saddle portion  354  and a shaft portion  356  adjustably disposed on the foot portion  314 . The saddle portion  354  has a generally arcuate or curvilinear shape to accommodate a tubular shape of the foldable frame  108 . The shaft portion  356  may be threadedly coupled to the foot portion  314 , such that rotation of the shaft portion  356  adjusts the height of the stop  352  and thus the distance between the seat  104  of the wheelchair  102  and the foot portion  314 . At least one threaded nut, bolt or similar component  358  may be disposed on the shaft portion  356  to secure the stop  352  at a particular height with respect to the foot portion  314 . As particularly illustrated in  FIG. 7 , a plurality of threaded nuts is utilized to secure the stop  352  to the foot portion  314 . Other embodiments of the seat engagement assembly  350  may also be utilized. For example, a cable having a pair of opposed ends coupled to the support structures  200  of the braking mechanisms  100   a  and  100   b  may be used. An adjustable pneumatic cylinder and piston rod may also be utilized.  
         [0059]      FIG. 6A  shows the sensing lever assembly  300  in the position where the wheel is engaged and no movement is possible. This position corresponds with an absence of a patient seated in the chair. When the patient sits on the seat, the rails  107  of the foldable frame  108  move downward as indicated by the arrows in  FIGS. 6B and 6C . The downward movement of the rails causes the seat engagement assembly  350  to move the sensing lever assembly  300  downward as shown, which, in turn, causes the wheel to be released for free movement.  
         [0060]     A wheelchair  102  with brake mechanisms  100   a  and  100   b  may be further enhanced by providing a means for bypassing the brake mechanism  100   a  and  100   b  when a user is not seated in the wheelchair  102 . Such bypass means makes it easier for an attendant to transport an empty wheelchair that would otherwise have the brake mechanisms  100   a  and  100   b  engaged. In example embodiments, as illustrated in  FIGS. 3, 5A ,  5 B,  5 C,  8 A- 12 , and  17 - 18 , a brake release assembly  400  is coupled to the foldable frame  108  and operably coupled to the support structure  200 . In one of the example embodiments, the brake release assembly  400  comprises at least one hand release lever  402  pivotally couplable to handles of the wheelchair  102 . A linkage  403  is coupled to and extends between the hand release lever  402  and the support structure  200  or braking lever  250 . The hand release lever  402  is pivotable between a depressed position or state and released position or state. As an attendant depresses the hand release lever  402  toward the depressed state it pivots the support structure  200  from the engaged position toward the disengaged position. As an attendant releases the hand release lever  402  from the depressed state toward the released stated, the support structure  200  pivots from the disengaged position toward the engaged position.  
         [0061]     Referring now to  FIGS. 5A-10B  and particularly to  FIG. 9 , the hand release lever  402  includes at least one flange  404  having an aperture or hole  405  for attaching at least one end of the linkage  403 . A second end of the linkage  403  is detachably coupled to the support structure  200  or braking lever  250 . In one example embodiment, the hand release lever  402  is preferably disposed generally above the handle of the wheelchair  102  to allow gravity to assist an attendant in applying the hand release lever  402 .  
         [0062]     In one example embodiment of the invention, the hand release lever  402  may be manufacture from stainless steel. Additionally, the hand release lever  402  may have a generally textured outer surface and/or a contoured surface to facilitate gripping and/or comfort for an attendant grasping the hand release lever  402 . Other configurations, materials and texturing are also contemplated by the present invention. Other materials may include aluminum, composite, polymer, or similar materials.  
         [0063]     The linkage  403  comprises a generally rigid rod or wire according to one embodiment. Linkage  403  may be manufactured from various other materials such as steel, aluminum, titanium, composite polymer, or fabric. Any device that would link the hand release lever  402  and the support structure  200  may be used and is contemplated by the present invention.  
         [0064]     A length adjustor  408  may be desirably disposed between a pair of linkage portions  406   a  and  406   b  to adjust an overall length of the linkage  403 . The length adjustor  408  is used because the distance between the handles of the wheelchair  102  and the placement of the support structure  200  may vary depending upon the manufacturer of the wheelchair  102 . The length adjustor  408  may comprise an elongate tube or cylinder having opposed open ends extending into an interior space thereof. Free ends of the linkage portions  406   a  and  406   b  may extend into the open ends of the length adjustor  408 . Fasteners  410 , such as screws, bolts or similar components may extend into the length adjustor  408  to engage and secure the linkage portions  406   a  and  406   b  in the interior of the length adjustor  408 . Other devices such as turnbuckles may also be used to adjust the overall length of the linkage  403 .  
         [0065]     In another example embodiment, a brake release coupling assembly  450  is provided to facilitate coupling the brake release assembly  400  to the wheelchair  102  without having to modify the wheelchair  102 . In this example embodiment, as illustrated in  FIGS. 8A-10C  and particularly  FIG. 10A , the brake release coupling assembly  450  comprises a pair of coupling members  460   a  and  460   b  detachably coupled together about the handle of the wheelchair  102 . Referring to  FIGS. 10A and 10B , each of the coupling members  460   a  and  460   b  includes a groove, recess or channel  462   a  and  462   b  extending into an inner surface thereof for receiving the foldable frame  108  defining the handles of the wheelchair  102 . As illustrated in  FIG. 10A , when the coupling members  460   a  and  460   b  are coupled together grooves  462   a  and  462   b  define an aperture extending through at least a portion of the coupling members  460   a  and  460   b.  As particularly illustrated in  FIG. 10B , each of the grooves  462   a  and  462   b  has a generally arcuate shape to accommodate the arcuate shape of the foldable frame  108 . The grooves  462   a  and  462   b  may have various shapes, such as a generally linear or an approximately right angle depending upon the shape of the foldable frame  108 .  
         [0066]     In another example embodiment, as illustrated in  FIG. 9 , each of the coupling members  460   a  and  460   b  may include a shoulder portion  466   a  and  466   b  respectively extending generally curvilinearly away therefrom. The grooves  462   a  and  462   b  of the coupling members  460   a  and  460   b  may extend along an inner surface of the shoulder portions  466   a  and  466   b  to accommodate a generally arcuate shape of the foldable frame  108 . The coupling members  460   a  and  460   b  may be machined from steel, aluminum, polymers, composites and similar materials. Additionally, the hand release lever  402  and the coupling members  460   a  and  460   b  may have a silver ion coating, which has been shown to kill bacteria, viruses and other pathogens.  
         [0067]     To assemble the brake release assembly  400  each coupling member  460   a  and  460   b  is positioned adjacent to respective side of the foldable frame  108 , such that the handles of the wheelchair  102  extend through the aperture defined by the coupling members  460   a  and  460   b.  Referring again to  FIG. 9 , fasteners  424 , such as screws, bolts and similar components, are utilized to couple the coupling members  460   a  and  460   b  together. The hand release lever  402  is pivotally coupled to the coupling members  460   a  and  460   b  with a fastener  426 , such as a screw, bolt and similar components.  
         [0068]     Referring generally to  FIGS. 5A-5B  and  8 A- 10 B, and  FIG. 10A  in particular, brake release assembly  400  may include a break release locking mechanism  500  operably coupled thereto to permit an attendant to maintain the support structure  200  in the disengaged position. In one example embodiment, a switch  510  is movably disposed to the coupling members  460   a  and  460   b  to selectively confront and prevent pivoting of the hand release lever  402  from the depressed state toward the released state. As discussed above, the support structure  200  is in the disengaged position when the hand release lever  402  is in the depressed state. Referring particularly to  FIG. 10B , an end of the switch is pivotally disposed in a notch  631  extending into a lower surface or bottom  632  of each of the coupling members  460   a  and  460   b.    
         [0069]     Referring back to  FIG. 10A , the switch  510  is positionable between a first locked position at A, a second locked position at B, and a released position at C. While the switch  510  is in the released position C, the hand release lever  402  will move freely from the depressed state toward the released state. An attendant can temporarily hold the hand release lever  402  in the depressed state by moving the switch  510  to the first locked position A and letting the flange  404  confront the switch  510 . The force exerted on the flange  404  by the biasing member  260  acting on the support structure  200  and the linkage  403  keeps the switch  510  in the first locked position A and prevents the hand release lever  402  from pivoting toward the released position.  
         [0070]     There are at least two methods for moving the switch  510  from the first locked position to the released C position. The first method occurs when a user sits in the seat  104  of the wheelchair  102 . As a user sits down, the support structure  200  pivots from the engaged position toward the disengaged position causing the linkage  403  to at least slightly displace the hand release lever  402 . The displacement of the hand release lever  402  reduces the pressure on the switch  510 , thereby permitting gravity to act on the switch  510  and move it to the released C position. Permitting movement of switch  510  from the locked position A to the released position C when a user sits in the seat  104  ensures brake mechanism  100   a  will move from the disengaged position toward the engaged position once the user attempts to rise up from the wheelchair  102 .  
         [0071]     The second method of moving the switch  510  from the first locked position A to the released position C occurs when an attendant depresses hand release lever  402 . Once the force created by the biasing member  260  acting on the support structure  200  and linkage  403  is removed from the switch  510 , gravity freely moves it toward the released position C.  
         [0072]     An attendant can also keep the hand release lever  402  in the depressed stated by moving the switch  510  to the second locked position B and letting the hand release lever  402  confront switch  510 . Once switch  510  is placed in the second locked position B, hand release lever  402  will not be able to move toward the released stated even if it is depressed again or a user sits in the seat  104  of the wheelchair  102 . The switch  510  is maintained in the second locked position B, by a securing assembly  560  operably disposed in at least one of the coupling members  460   a  or  460   b.    
         [0073]     In one example embodiment, as illustrated in  FIG. 10B , the securing assembly  560  comprises a coiled spring or other biasing member  562  disposed in a bore  566  extending through the coupling member  460   a  or  460   b  and into the notch  631 . An engagement member  564 , such as a ball bearing or similar device, is also disposed in the bore  566  and is biased against a portion of the switch  510  when it is in the second locked position B. The bore  566  may have a diameter slightly smaller than a diameter of the engagement member  564  or it may taper toward the notch  631 , such that the engagement member  564  is prevented from completely escaping from the bore  566  when the switch  510  in not in the second locked position B. A fastener  568  may also be threadedly disposed in the bore  566  to facilitate removably retaining the securing assembly  560  in the bore  566 . To permit the hand release lever  402  to move from the depressed state toward the released state, and simultaneously move the support structure from the disengaged position toward the engaged position, an attendant forces or pivots switch  510  toward release position C, whereby the biasing member  260  and linkage  403  force the hand release lever  402  to move from the depressed state toward the released state.  
         [0074]     In another embodiment, as illustrated in  FIG. 10C , a locking collar  570  may be tethered by a strap  572 , chain or similar structure to the coupling portions  460   a  and/or  460   b.  The locking collar  570  is operably couplable about the hand release lever  402  and the handle of the wheelchair  102  when the hand release lever  402  is in the depressed state. The locking collar  570  may comprise an annular ring or plate having an aperture extending therethrough for receiving the hand release lever  402  and the handle of the wheelchair  102 . In other embodiments, the locking collar  570  may comprise a plate or ring having a C-shape, U-shape or similar shapes.  
         [0075]     In some instances it may not be advisable to have a wheelchair that can move freely when a user or patient is seated; for example, if the patient is suffering from Alzheimer&#39;s or other similar diseases that affects a patient&#39;s memory. In this instance, as illustrated in  FIGS. 8A and 8B , the brake mechanisms  100   a  and  100   b  include only a support structure  200  and a braking lever  250  pivotally coupled to the foldable frame  108 . There is no sensing lever assembly  300  to pivot the support structure  200  from the engaged position toward the disengaged position. As discussed above, the biasing member  260  extends between the support structure  200  or braking lever  250  and a portion of the foldable frame  108  to maintain the support structure  200  in the engaged position. When a user sits in the seat  104  of the wheelchair  102  it does not move the support structure  200  and braking lever  250  to the disengaged position.  
         [0076]     The brake release assembly  400  may be utilized to facilitate transport of either the patient seated in the wheelchair  102  or an empty wheelchair  102 . In this example embodiment, the relationship of a user or patient&#39;s position in the seat  104  of the wheelchair  102  does not affect the brake mechanisms  100   a  and/or  100   b.  In this particular example embodiment, securing assembly  560  may not be disposed in the bore  566  of one of the coupling members  460   a  or  460   b.  Instead, a pin or similar structure may be securely or removably disposed therein to prevent the hand release lever  402  from being secured in the depressed state. This arrangement ensures that the wheelchair  102  is always locked unless an attendant is present. An attendant can still temporarily lock hand release lever  402  in position A to transport the wheelchair  102 . However, as discussed above, as soon as a user is seated in the wheelchair  102  the switch  510  automatically moves to the released position C to ensure that the wheelchair  102  will be secured if the user attempts to rise up from the wheelchair  102 .  
         [0077]     Occasionally, attendants transporting patients in wheelchairs  102  have to maneuver the wheelchairs  102  down an incline, such as a long sloping driveway, or a wheelchair access ramp of a building. Referring to  FIGS. 11-18 , a friction brake assembly  600  may be coupled to a wheelchair  102  in conjunction with the brake mechanisms  100   a  and  100   b.  Additionally, the friction brake assembly  600  may be used with ( FIG. 11 ) or without ( FIG. 12 ) the sensing lever assembly  300  pivotally coupled to the support structures  200 . In one example embodiment, as illustrated in  FIGS. 13-15 , the friction brake assembly  600  includes a control lever  610  comprising a plate portion  612  disposed adjacent to a top of the drive wheel  110   a  and/or  110   b  and an anchor portion  614 . The plate portion  612  is oriented in a generally horizontal plane such that a lower surface of the plate portion  612  confronts the drive wheel  110   a  and/or  110   b  to slow rotation thereof while the wheelchair  102  is moving either on a flat surface or down an incline. In one embodiment, the anchor portion  614  is disposed between the drive wheel  110   a  or  110   b  and the foldable frame  108  and is oriented at a generally right angle to the plate portion  612 . However, it is contemplated that the anchor portion  614  may be oriented at any angle with respect to the plate portion  612 .  
         [0078]     As particularly illustrated in  FIG. 15 , the anchor portion  614  may be pivotally coupled to the support bracket  210 , such that the support structure  200  and the anchor portion  614  have generally the same pivot point. A spacer (not shown) comprising a cylinder, washer or a similar structure, may be disposed between the anchor portion  614  and the support structure  200  to prevent operational interference. The plate portion  612  may have a front edge  620  and rear edge  622  corresponding with a front and rear of the wheelchair  102 . The rear edge  622  of the plate portion  612  may have a generally smaller width than the front edge  620  such that the plate portion  612  has a generally triangular shape. The plate portion  612  may have any shape such as generally curvilinear or arcuate to accommodate the curvature of the drive wheels  110   a  and  110   b.  Other shapes and configurations such as C-shaped, U-shaped, V-shaped are also contemplated and considered to be within the spirit and scope of the invention.  
         [0079]     As illustrated in  FIGS. 11-18  and particularly  FIGS. 16 and 17 , an attendant operated friction brake actuation lever  630  is pivotally coupled to the coupling members  460   a  and  460   b  to actuate the control lever  610 . The brake actuation lever  630  is positioned generally below the handle of the wheelchair  102  and oriented generally parallel to the handle of the wheelchair  102 . As shown in  FIG. 18 , the brake actuation lever  630  is pivotally disposed in an aperture  632  defined by grooves  634   a  and  634   b  extending into inner surfaces of the coupling members  460   a  and  460   b.    
         [0080]     Referring to  FIGS. 16 and 17 , a linkage  640  is coupled to and extends between the brake actuation lever  630  and either the plate portion  612  or the anchor portion  614  of the control lever  610 . A length adjuster  408  may be disposed between a pair of linkage portions  642   a  and  642   b  to adjust an overall length of the linkage  640 . The adjustment of the linkage  640  is identical to the adjustment of the linkage  403  described in detail above.  
         [0081]     In operation, as the wheelchair  102  accelerates down the incline, the attendant can squeeze the friction brake actuation lever  630  toward the handle of the wheelchair  102 , and concurrently the linkage  640  pivots the control lever  610  causing the plate portion  612  to engage the drive wheel  110   a  and/or  110   b.  By releasing the brake actuation lever  630 , the plate portion  612  pivots away from and disengages the drive wheel  110   a  and/or  110   b.    
         [0082]     In one embodiment, some or all of the components of the present invention are made from materials capable of withstanding the temperatures or harsh chemicals associated with autoclaving or sterilization. The materials capable of being autoclaved or sterilized include, but are not limited to, stainless steel, aluminum, composite polymers, and other materials known to one skilled in the art.  
         [0083]     Details of the present invention may be modified in numerous ways without departing from the spirit or scope of the present invention. For example, adjustable turnbuckles that adjust spring tension for different weight users could be replaced with a metal strap with a series of holes for different weight settings. Also, the hand release handles could utilize a clamp mounting mechanism to mount the handle on the back of the chair so that there would be no holes to drill to mount the brake system to the wheelchair. Various components of the present invention may be altered in shape or size without affecting the functionality of the device. Those skilled in the art will recognize other modifications or alternatives of the present invention without departing from the spirit or scope thereof.  
         [0084]     Although the present invention has been described with reference to particular embodiments, one skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention. Therefore, the illustrated embodiments should be considered in all respects as illustrative and not restrictive.