Abstract:
The present invention relates to a cordless braking system for a mobility-aiding device, such as a wheeled walker (a rollator) or a transport chair. The cordless braking system includes a brake actuating linkage, disposed inside the leg and handlebar members of the mobility-aiding device, which extends during height adjustment of the handlebars. The brake-actuating linkage and the leg/handlebar of the mobility-aiding device are designed to enable a locking pin or bolt to extend all the way therethrough to ensure that all of the height-adjustable members are secured together during use.

Description:
CROSS REFERENCE TO RELATED PRIOR ART 
   The present application is a continuation-in-part of U.S. patent application Ser. No. 10/692,092 filed Oct. 23, 2003, which is a divisional of U.S. patent application Ser. No. 09/908,102 filed Jul. 18, 2001, which issued as U.S. Pat. No. 6,659,478 on Dec. 9, 2003, which claims priority from Canadian Patent Application No. 2318028 filed Sep. 12, 2000, all of the United States Patent applications are incorporated herein by reference. 

   BACKGROUND OF THE INVENTION 
   The present invention relates to a wheeled walker, which can be used as a transport chair, and in particular to a novel braking system for wheeled apparatus. 
   Many persons, by reason of age or disability have difficulty in walking without a walking aid. Wheeled walkers or rollators are widely used by many such persons to assist in mobility. A wheeled walker typically has a frame mounted on four wheels and a pair of rearwardly extending handlebars, which the user can grip for support while walking. The user positions himself between the handlebars behind the walker, and pushes the walker forward. The wheels permit the user to roll the walker smoothly over the ground, thereby avoiding the laborious action of picking up and moving a non-wheeled walker in step-by-step fashion. The handle bars can be fitted with brake levers that when squeezed by the user, actuate some form of wheel braking mechanism. 
   Wheeled walkers are routinely equipped with a seating surface that permits the user to rest in the sitting position. The seating surface is usually positioned transversely between the handlebars within the wheelbase of the walker to offer a stable platform for sitting. In order to use the seating surface, the user must turn around and sit down in the rearward facing direction, opposite to the normal direction of travel, with his feet resting on the ground. The braking mechanism can be fitted with a locking mechanism to maintain braking engagement with the wheels to prevent the walker from rolling while the user is sitting. 
   While the provision of a seat to permit the user to rest is a useful feature, it often occurs that the user is too tired to continue walking and requires the assistance of a caregiver to continue travel. Conventional wheeled walkers are not adapted to support a seated user and be pushed by a caregiver. In particular, because the user is seated in a rearward facing position between the handlebars, there is very little space between the user and the caregiver, making it difficult for the caregiver to take walking steps without interfering with the feet of the user. Moreover, there is no dedicated means on conventional walkers to support the feet of the user while in the sitting position with the result that the feet are usually dragged across the ground or propped up on a frame member in an unnatural position. 
   There have been a number of attempts to provide a wheeled apparatus that is useful as a self-propelled walker and also as a caregiver propelled transport chair. 
   U.S. Pat. No. 5,451,193 discloses a combined wheelchair and walker. In the normal walking position, the seating surface is pivoted up rearwardly toward the seat back to provide space between the handlebars for the user to walk. The user walks in a forward direction pulling the walker behind him. When the user wishes to sit, the seating surface can be flipped down. There is no provision to permit the walker to be pushed by a caregiver. Indeed, the patent discloses that a third party must pull the seated user backwards by pulling on the seat back. 
   U.S. Pat. No. 5,451,193 discloses a combination wheelchair and walker. While the user or the caregiver can push the apparatus from behind as a conventional walker or transport chair, in order to assume the seated position, the user must walk around to the front of the apparatus, which manoeuvre can be difficult for a physically challenged person. 
   U.S. Pat. No. 5,605,345 discloses a wheeled apparatus for use both as a walker and a wheelchair. The design has rearward facing handlebars to permit the apparatus to be used as a wheeled walker. The design also has a bi-directional seating arrangement. When the seat is placed in the rearward facing position, it permits the person using the device as a walker to rest in a seated position by turning around and sitting down in the rearward facing direction with his feet resting on the ground. When the seat is placed in the forward facing position, the apparatus can be used as a conventional wheelchair. The wheelchair design is conventional in that it has large rear wheels with hand-rings that permit the wheelchair to be propelled by the occupant or rearward facing handles to permit the wheelchair to be pushed by a caregiver. 
   While the design disclosed in U.S. Pat. No. 5,605,345 offers significant advantage, it is not well adapted for use as a walker. Because it is based on a conventional wheelchair design, it is heavy and bulky, making it difficult to manoeuvre in confined locations. Furthermore, the bi-directional seating arrangement uses a frame mounted link arrangement, which cannot be practicably adapted to a light walker design. Because the seat back is pivoted to the seat base, the vertical rise of the seat back is limited and accordingly offers only lower back support. Furthermore, when positioned in the walker mode, the seat back obscures the user&#39;s view of the ground directly in front of the walker. 
   Conventional walkers have been equipped with handle bar mounted braking system actuators that permit the user to manually apply braking force when walking or to lock the brakes to permit the user to safely assume a seated position. For example, one such system is disclosed in U.S. Pat. No. 5,279,180, and relates to a cable braking system. The actuating mechanism uses a connecting lever to pull the cable when the brake lever is raised to a braking position or depressed to a locked position. 
   Thus, there remains a need for a walking aid that offers all of the functionality of a conventional wheeled walker and can be readily converted for use as a transport chair. 
   Cable type braking systems are commonly used on walkers, which have height adjustable handlebars. In such a case, the flexible cable accommodates the variable length between the brake handle actuator and the wheel mounted braking element. However, cable type braking mechanisms have a number of deficiencies. In particular, the cables require rather precise and periodic adjustment to maintain effective braking action. Moreover, because the cables are routed from the brake handle actuator to the wheels outside of the frame and require some slack to accommodate height adjustability, the resulting loop or bight in the cable is prone to catching or snagging on other objects, a deficiency which is particularly problematic in the case of a folding style walker that is transported in the trunk of a car. 
   A simple solution for eliminating the brake cable is to provide a solid rod linkage between the brake-handle actuator and the braking element that extends down through the two telescoping parts of the height-adjustable handle bar. Unfortunately, the solid rod linkage prevents a pin, bolt or screw from passing through both the telescoping parts of the height-adjustable handlebars, which would normally provide a secure, but adjustable means for locking the telescoping parts together. Since safety is the ultimate priority for these types of devices, it is important that the height adjustable handlebars are securely reconnected after adjustment. One solution to this problem is disclosed in U.S. Pat. No. 6,283,484 issued Sep. 4, 2001 in the name of Malmström, which provides an adjustable brake rod inside the telescoping handlebars. Unfortunately, the Malmström device relies on a single friction screw, which extends through the outer telescoping parts of the handle bars into frictional engagement with the inner telescoping brake rods, to hold the two telescoping parts of the handlebar and the two telescoping parts of the brake rod together. This system relies heavily on the strength of the user, and on the durability of the frictionally engaged materials. Frequent tightening and loosening by elderly or otherwise disabled users make this type of system susceptible to accidental slippage, and therefore unacceptably dangerous. 
   An object of the present invention is to overcome the shortcomings of the prior art cable and cordless based systems by providing a cordless brake actuating system for a height adjustable handlebar that enables a locking screw, pin or bolt to extend through both parts thereof. 
   SUMMARY OF THE INVENTION 
   Accordingly, the present invention relates to a height-adjustable, manually-actuated brake device for use with a wheel mounted on a height-adjustable frame, which includes a lower telescopic member, an upper telescopic member, and a locking pin for extending through both the upper and lower telescopic members, comprising:
         a brake mounted on the lower telescopic member;   a manually-engageable brake actuator for actuating the brake;   an upper leg extending from the brake actuator through the upper telescopic member, the upper leg including a gap for receiving the locking pin, which extends therethrough;   a lower rod adjustably connected to the upper leg and extending through the lower telescopic member, the lower rod including a slot for receiving the locking pin, which extends therethrough; and   an adjustable connector for locking the upper leg and lower rod together at any one of a plurality of positions.       

   Another feature of the present invention relates to a mobility aiding device comprising:
         a frame including front and rear support members, the rear support members having upper and lower telescoping members;   a locking pin for extending through the upper and lower telescoping members for locking the relative position thereof;   front wheels mounted on the front support members;   rear wheels mounted on the rear support members;   a moveable brake mounted on the frame for hindering the rotation of one of the front or rear wheels;   a manually-engageable brake actuator for actuating the brake;   an upper leg extending from the brake actuator through the upper telescopic member, the upper leg including a gap for receiving the locking pin, which extends therethrough;   a lower rod adjustably connected to the upper leg and extending through the lower telescopic member, the lower rod including a slot for receiving the locking pin, which extends therethrough; and   an adjustable connector for locking the upper leg and lower rod together at any one of a plurality of positions.       

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a front right perspective view of the walker/transport chair of the present invention with the back rest in the walker position; 
       FIG. 2  is a right side view of the walker/transport chair of the present invention with the back rest in the walker position; 
       FIG. 3  is a plan view of the walker/transport chair of the present invention with the back rest in the walker position; 
       FIG. 4  is a right side view of the walker/transport chair of the present invention with the back rest in the transport chair position; 
       FIG. 5  is a plan view of the walker/transport chair of the present invention with the back rest in the transport chair position; 
       FIG. 6  is a right side view of the back rest extension arm; 
       FIG. 7  is a left side view the back rest extension arm; 
       FIG. 8  is a perspective view showing the manner in which the backrest is connected to the extension arms; 
       FIG. 9  is a front view of the cross-bar member; 
       FIG. 10  is a top plan view of the cross-bar member; 
       FIG. 11  is a right side view in partial section of the cross-bar member connection details; 
       FIG. 12  is a side view of the inside of the right brake housing half; 
       FIG. 13  is a side view of the inside of the left brake housing half; 
       FIG. 14  is a left side view of the brake actuator slide; 
       FIG. 15  is a rear view of the brake actuator slide; 
       FIG. 16  is a right side view of the brake actuator slide; 
       FIG. 17  is a side view of the inside of the right brake housing half showing the position of the brake actuator slide; 
       FIG. 18  is a left side view of the brake lever; 
       FIG. 19  is a right side view of the brake lever; 
       FIG. 20  is a side view of the inside of the left brake housing half showing the brake lever in the neutral position; 
       FIG. 21  is a side view of the inside of the left brake housing half showing the brake lever in the depressed brake locking position; 
       FIG. 22  is a side view of the inside of the left brake housing half showing the brake lever and the brake actuator slide in the neutral position; 
       FIG. 23  is a side view of the inside of the left brake housing half showing the brake lever and the brake actuator slide in the raised brake actuating position; 
       FIG. 24  is a side view of the inside of the left brake housing half showing the brake lever in the depressed brake locking position; 
       FIG. 25  is a right side view in partial section of the internal brake actuating mechanism of the present invention; 
       FIG. 26  is a perspective view of the brake wire clamp; 
       FIG. 27  is a right side view, in partial section showing the brake shoe connection details; 
       FIG. 28  is a perspective view of the brake shoe; 
       FIG. 29  is a side view of the brake shoe showing the position of the friction member; 
       FIG. 30  is a perspective view of the friction member; and 
       FIG. 31  is an exploded side view of a second embodiment of the internal brake actuating mechanism; 
       FIG. 32  is an isometric view of the upper brake leg of  FIG. 31 ; 
       FIG. 33  is a side view of the upper brake leg of  FIG. 32 ; 
       FIG. 34  is a side view of the lower brake rod of  FIG. 31 ; 
       FIG. 35  is a side view of the lower brake rod of  FIG. 34 ; and 
       FIG. 36  is cross sectional view of the connection for the lower end of the lower brake rod of  FIGS. 34 and 35 . 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring to  FIGS. 1 to 3 , there is shown a perspective view of a rollator or walker/transport chair  10  in the walker configuration. Walker/transport chair  10  has a pair of forward leg members  12 , a pair or rearward leg members  16 , and a U-shaped transverse seat support member  20 . Front leg members  12  are fixedly secured at their upper ends to front leg brackets  22 , and rear leg members  16  are fixedly attached at their upper ends to rear leg brackets  26 . Front leg brackets  22  are pivotally attached to rear leg brackets  26  at pivot pins  30 . In the open or operative position shown in  FIGS. 1 to 3 , abutment surfaces  32  at the upper ends of front leg brackets  22  engage the forward lower edge of seat support member  20 , when forward leg members  12  are in the open and weight bearing position. Front leg brackets  22  permit the front leg members  12  to be folded toward rear leg members  16  in order to collapse walker/transport chair  10  into a more compact configuration, e.g. for placement in the trunk of a car. 
   Walker/transport chair  10  is locked in the open position by means of lock rod  73 , which engages projections  75  on front leg brackets  22 . Handle  77  is rotatably mounted about transverse seat support member  20  for moving lock rod  73  out of engagement with projections  75 . Handle opening  36  is provided in seating surface  34  to provide easy access to handle  77 . 
   Seating surface  34  is horizontally supported at its forward edge  90  by transverse seat support member  20  and provides a stable seating platform. Seating surface  34  is pivotally attached to transverse seat support member  20  such that it can be flipped to a vertical position by pulling up on rear edge  71 . This position is particularly useful when the user wishes to move as far forward as possible, for example when reaching ahead of the walker/transport chair  10  to remove objects from a cupboard. 
   Front leg members  12  are stabilized by crossbar member  68 , which extends horizontally between front leg members  12  and is fixedly secured to the bottom ends of front leg members  12  at end fittings  40 . Front wheels  38  are mounted on front fork assemblies having a vertical axle shaft carried in a bearing assembly (not shown) in each end fitting  46  for rotation about the vertical axis to permit front wheels  38  to caster for ease of steering walker/transport chair  10 . 
   Rear wheels  42  are carried at the lower ends of rear leg members  16  on rear fork assemblies  44 . Rear fork assemblies  44  are fixedly connected to the lower ends of rear leg members  16 . 
   Push handle assemblies  50  are fixedly attached to the upper ends of telescopic tubes  52  which are slidably received in rear leg members  16 . The height of push handle assemblies  50  can be adjusted by extending or retracting telescopic tubes  52  in rear leg members  16 . Telescopic tubes  52  have a series of through holes at uniform spacing along their length through which thumb screws (or other locking pin or bolt)  54  can be selectively inserted to fix push handle assemblies  50  at the desired height. 
   Push handle assemblies  50  comprise handgrips  60 , handle housings  62  and brake levers  64 . Brake levers  64  are operatively connected to brake shoes  66  by length-adjustable rod assemblies housed within the telescopic tubes  52  and the rear leg members  16 . Movement of the brake levers  64  will cause the brake shoes  66  to move into braking engagement with the tread of rear wheels  42  thereby arresting rolling motion. 
   When walker/transport chair  10  is in the walker configuration as shown in  FIGS. 1 to 3 , the user positions himself behind walker/transport chair  10 , and between push handle assemblies  50  facing the forward direction. In order to function as an effective walker, it is desirable that the geometry of the walker be such that the user can position himself far enough forward that his center of gravity is vertically aligned over handgrips  60 . This will permit the user to support a substantial portion of his weight on handgrips  60  when desirable to reduce the weight on the feet. 
   In order to ensure stability of the rollator  10  when a substantial vertical load is placed on handgrips  60 , the handgrips must be positioned forward of the point of ground contact of rear wheels  42 . Moreover, in order to facilitate walking, there must be sufficient room in front of the user to permit him to extend his feet forward in a natural walking gait without interfering with the rollator structure, and in particular with the seating surface. Accordingly, the position of seating surface  34  is biased to the front of walker/transport chair  10  such that its rear edge  71  is forward of handgrips  60 . In addition, seating surface  34  can be flipped to a vertical position about transverse seat support member  20  as described above. This will provide the user with additional space to move forward between push handle assemblies  50  if desired. 
   When the user wishes to rest, he simply turns around between push handle assemblies  50 , using handgrips  60  for support if required, and sits down on seating surface  34 , with his feet on the ground. Backrest  70  is provided to support the user&#39;s back while seated on walker/transport by chair  10 . Backrest  70  is attached to extension arms  72  which are fixed at their rearward ends to push handle assemblies  50 . 
     FIGS. 6 ,  7  and  8  show the details of extension arms  72  and the manner in which backrest  70  is attached to extension arms  72 . The extension arms  72  each have an inward facing part-annular recess  96  with a central cylindrical bore  98  formed therethrough. The backrest  70  has formed therein two mounting points  100  and  102  for attachment to extension arm  72 . Mounting point  100  can be used as the point of attachment for a larger user whereas mounting point  102  effectively shortens the length of backrest  72  for a smaller user. The configuration of mounting points  100  and  102  is identical and will be described with reference to point  102 , which is visible in  FIG. 8 . 
   The backrest  70  is formed of a flexible plastic material and at each end has a connection piece  80 . The backrest  70  and the connection piece  80  can be unitarily molded of a suitable plastic material that has sufficient flexibility in the central back-supporting area to conform to and support a user&#39;s back and sufficient mechanical strength to function as a connection piece. In the alternative, the backrest  70  and the connection piece  80  can be separate components joined together. Moreover, the backrest  70  can be formed of a rigid material such as aluminum if a non-flexible back strap type backrest is desired. The connection piece  80  has an outwardly projecting key type lug  82  and a central bore  84  formed therethrough. Part-annular recess  96  in extension arm  72  is sized to fit over and closely receive key type lug  82  on backrest  70  with the cylindrical bores  84  and  98  axially aligned. A suitable bolt (not shown) with a smooth shank passes through cylindrical bores  84  and  98  and is fastened with a captive nut (not shown) located in hex-head recess  86  in connection piece  80 . In this manner, backrest  70  is pivotally connected to extension arms  72 . 
   Stop lug  104  projects inwardly of recess  96  in extension arm  72 . Abutment surface  106  on stop lug  104  limits forward rotation of backrest  70  by contacting key type lug  82  in connection piece  80  and maintains backrest  70  in the forward facing horizontal position. Similarly, abutment surface  108  limits-rotation of backrest  70  by contacting key type lug  82  in connection piece  80  and maintains backrest  70  in the rearward facing horizontal position. This arrangement permits backrest  70  to be manually flipped from the forwardly extending position shown in  FIGS. 1 to 3  for use in the walker mode, to the rearwardly facing position, shown in  FIGS. 4 and 5  for use in the transport chair mode. 
   When walker/transport chair  10  is in the transport chair configuration, the user or a care-giver flips backrest  70  to the rearward extending position as shown in  FIGS. 4 and 5 . The user positions himself in front of and facing away from walker/transport chair  10  and sits down on seating surface  34  with his back against backrest  70 . Footrest  72  is then folded from the stowed position shown in  FIGS. 2 and 3  to the deployed position shown in  FIGS. 4 and 5 . In this position, i.e. the transport chair mode, the user rests his heels on footrest tray  76 , and can be comfortably propelled by the caregiver. (Footrest  72  has been omitted from  FIG. 1  to show greater detail of crossbar  68 ). The forward facing seated position is not only useful when the apparatus is being propelled by a caregiver in the transport chair mode, but also permits the apparatus to be positioned close to a table, for example when eating a meal. Conventional walkers in which the user is seated in the rearward facing position are not well suited to this application because the rearward projecting handgrips and the rear wheels limit how close the walker can be placed, while the seating surface is typically positioned far forward of the handgrips. 
   Conventional walkers usually require a crossbar between the front leg members to strengthen the frame against collapse when the walker is bearing substantial weight, for example, when the user is seated. A front crossbar is particularly required where the front leg members are pivotally attached to the frame to permit folding, which pivotal attachment provides little resistance to outward splaying of the legs under load. 
   For conventional walkers, the presence of a crossbar between the front legs of the walker typically does not interfere with the user&#39;s movements, as the user is positioned behind the walker in both the walking and sitting positions. However, the front crossbar on a conventional walker interferes with its use as a transport chair. In particular, in order to assume the forward facing sitting position in the transport chair mode, a user must be able to position his heels very close to a point on the ground directly under the front edge of the seating surface. If the user is positioned too far forwards, he tends to lose balance when attempting to assume the seated position, falling backward in an uncontrolled manner onto the seating surface. This can cause the walker to upset resulting in serious injury to the user. Conventional cross-bars are usually positioned well forward of the front edge of the seating surface and accordingly tend to prevent a user from positioning his heels close to a point on the ground directly under the front edge of seating surface. 
   The walker/transport chair design of the present invention is configured to overcome the limitations of conventional walker frame design. First, as seen in  FIG. 1  front leg members  12  are positioned at an angle closer to vertical than are most conventional walkers. This minimizes the extent to which the lower ends of front leg members  12 , and consequently crossbar  68 , project forward of the forward edge  90  of seating surface  34 . However, this has the undesirable effect of shortening the wheelbase and lessening stability. In order to provide for a lengthened wheelbase, the front fork assemblies  48  are not secured axially inside the lower end of front legs  12 , as is conventional practice in walker design. Instead, front fork assemblies  48  are secured in end fittings  40 , which project forwardly from the lower end of leg members  12 , effectively lengthening the wheelbase. 
   Another feature of the present invention that enhances its use as a transport chair is the design of crossbar  68 . As best shown in  FIGS. 4 and 5 , cross-bar  68  attaches to front leg members  12  at their lower ends, which point is forward of the forward edge  90  of seating surface  34 . In order to permit the user to more safely assume the forward-facing seated transport chair position, cross-bar  68  is rearwardly curved such that its central portion is located substantially under the forward edge  90  of seating surface  34 . This curved cross-bar arrangement permits the user to place his heels close to a point on the ground directly under the front edge of seating surface, and thereby. While a curved geometry is shown in the drawings, other configurations could be used so long as the crossbar is configured such that its central portion is located substantially under or behind the forward edge  90  of seating surface  34 . 
   Construction details of crossbar  68  and end fittings  40  can be seen in  FIGS. 9 to 11 . Crossbar  68  and end fittings  40  are unitarily molded or cast from a material of suitable strength. For example crossbar  68  can advantageously be formed of cast aluminum. Cylindrical bores  120  are provided in crossbar  68  to receive connector piece  122 , which is bolted into the lower ends of forward leg member  12 . Front fork shaft  124  is vertically received in bore  126  and is rotatably retained by upper and lower bearings  128  fitted in bore  126 . 
   As noted above, the front fork assemblies of conventional walkers are typically inserted directly into the hollow ends of the leg members. The fork-mounting shaft is usually carried in a single bearing, which is press-fitted into the bottom end of the leg member. This arrangement is prone to failure. In particular, repetitive striking of the wheels into curbs and other obstacles and impact over rough road surfaces has a tendency to deform and widen the lower end of the leg members into which the bearing is pressed. This can cause the bearing, and the entire fork/wheel assembly to fall out of the bottom of the leg member. By mounting the front fork assemblies  48  to end fittings  40  fitted with two bearings, rather than directly into a single bearing in the bottom end of the leg, the ability of the fork assemblies and the lower leg mounting hardware to absorb shock, without failure is greatly improved. 
   The design of the walker/transport chair  10  permits the use of a novel and effective braking system. Conventional walkers use Bowden cables, which extend from the handgrip mounted brake levers to the braking wheels. Bowden cables are relatively inexpensive and because they are flexible, can be installed with excess length in a freestanding loop or bight to accommodate changes in length occasioned by the adjustment of handgrip height. However, the use of a Bowden cable arrangement has a number of disadvantages. The same freestanding loop or bight that permits handgrip height adjustability is prone to being caught or hooked on various obstructions, particularly when the walker is loaded into, or unloaded from the trunk of a car. In addition, Bowden cables must be accurately adjusted and even a slight lack of adjustment can cause unsatisfactory braking action. 
   The design of the present invention permits the use of an internal brake actuating mechanism. Referring to  FIGS. 12 and 13 , a handle housing  62  comprises right side housing shell  200  and left side housing shell  202 , which are bolted at their lower ends to telescopic tube  52 . The handgrip  60  is bolted between right side housing shell  200  and left side housing shell  202  at their upper ends. The brake lever  64  is retained between right side housing shell  200  and left side housing shell  202  in the manner described below. 
   Referring to  FIG. 12 , the inside face of right side housing shell  200  is shown. Raised wall  204  forms an elongated groove  206  on the inside face with a longitudinal axis that is parallel to telescopic tube  52 . Semicircular bearing surfaces  208  are formed in the lower portion of the inside face. 
   Referring to  FIGS. 14 to 16 , brake actuator  210  has raised tongue portion  212 , which is sized to be slidably retained in elongated groove  206  of right side housing shell  200 , and cylindrical portion  214 , which is sized to be slidably retained in semicircular bearing surfaces  208  of right side housing shell  200 . 
     FIG. 17  shows the position of brake actuator  210  when it is slidably received in right side housing shell  200 . Bias spring  218  is carried between retaining lug  216  formed at the upper end of brake actuator  210  and stop wall  220  formed at the upper end of groove  206  and biases brake actuator  210  in the downward direction. Brake actuator  210  has elongated aperture  215  formed through cylindrical portion  214 . This elongated aperture  215  permits cylindrical portion  214  to extend down into telescopic tube  52  and allow bolts to pass through bolt holes  217  in right side housing shell  200 , telescopic tube  52 , elongated aperture  215 , telescopic tube  52  and bolt holes  217  in left side housing shell without interfering with the vertical sliding motion of brake actuator  210 . Such a through-bolting arrangement greatly improves the mechanical strength of the attachment of push handle assemblies  50  to telescopic tubes  52 . 
   Referring to  FIGS. 18 and 19 , brake lever  64  comprises upper arm  220  and lower arm  222  joined at their rear extremities by ball shaped gripping projection  224 . Brake lever  64  is shaped such that braking action, as more completely described below, can be effected by placing the hands on handle grips  50 , inserting fingers through opening  226  and pulling up on upper arm  220  with inward gripping action. Downward pressure on lower arm  222  will move brake lever  64  downward into a locked or “parked” position, also as more completely described below. Ball shaped gripping projection  224  assists in moving brake lever in a downward direction by enabling the user to hook a thumb over the projection to apply downward force. This is particularly useful for a user with strength or mobility limitations in the hands. 
   Pivot pin  228  projects from the left side of brake lever  64  at its forward end and is sized to be received in slot  230  ( FIG. 13 ) formed in the inside surface of left side housing shell  202 . Brake actuating lug  232  projects from the right side of brake lever  64  and its upper surface engages downward facing abutment surface  234  formed in brake actuator  210 . Camming lug  236  projects from the left side of brake lever  64 . A brake-lock actuating lug  238  projects from the right side of brake lever  64  at its forward end opposite pivot pin  228 . 
   Referring to  FIGS. 20 and 22 , brake lever  64  is shown in the neutral position when no manual braking action is applied. In this position, the brake lever  64  projects rearwardly in a direction slightly below horizontal. Pivot pin  228  rests at the bottom of slot  230  in left side housing shell  202  and camming lug  236  (shown in phantom lines) rests on upward facing abutment surface  240  formed on the inside surface of left side housing shell  202 . Brake lever  64  is retained in this position by the downward pressure of bias spring  218  acting on brake actuator  210 , as can be seen with reference to  FIG. 17 . 
   Downward facing abutment surface  242  (shown in phantom lines) formed in brake actuator  210  abuts the upper surface of the brake-lock actuating lug  238  (shown in phantom lines) formed in brake lever  64  and the downward action of bias spring  218  on brake actuator  210  urges pivot pin  228  to the bottom of slot  230 . Similarly, downward facing abutment surface  234  (shown in phantom lines) formed in brake actuator  210  abuts the upper surface of brake actuating lug  232  (shown in phantom lines) formed in brake lever  64  and the downward action of bias spring  218  on brake actuator  210  urges camming lug  236  into engagement with upward facing abutment surface  240 . 
   Thus in the neutral position as shown in  FIGS. 20 and 22 , brake lever  64  rests with pivot pin  228  at the bottom of slot  230  and camming lug  236  resting on upward facing abutment surface  240 . Brake actuator  210  is urged downwardly by bias spring  218  and rests with downward facing abutment surface  242  resting on brake lock actuating lug  238  and downward facing abutment surface  234  resting on brake actuating lug  232 . 
   Referring to  FIG. 23 , brake lever  64  is shown in the braking position when manual braking action is applied. In this position, the brake lever  64  has been pivoted about pivot pin  228  in the bottom of slot  230  until the upper arm  220  of brake lever  64  is substantially horizontal. This pivoting action causes brake-actuating lug  232  (shown in phantom lines) to raise brake actuator  210  by engagement with downward facing abutment surface  234  (shown in phantom lines). By manually releasing brake lever  64 , bias spring  218  will urge brake actuator  210  back to the neutral position shown in  FIG. 13 . The upward motion of brake actuator  210  between the neutral and braking positions is transmitted to rear wheel brake shoes  66  in a manner described below. 
   Referring to  FIGS. 21 and 24 , brake lever  64  is shown in the locked or “park” position. In this position, brake lever  64  has been pivoted down about camming lug  236  (shown in  FIG. 21  in phantom lines). This pivoting motion causes pivot pin  228  to move upward in slot  230  and draws camming lug  236  forward over upward facing abutment surface  240  onto lower abutment surface  246 . 
   As can be seen with reference to  FIG. 24 , this pivoting motion causes brake lock actuating lug  238  (shown in phantom lines) to raise brake actuator  210  by engagement with downward facing abutment surface  242  (shown in phantom lines). Brake lever  64  is retained in this locked or “park” position by the downward pressure of bias spring  218  acting on brake actuator  210  which urges camming lug  236  backwards into engagement with forward facing abutment surface  248 . Downward bias is also provided by spring  290  (see  FIG. 27 ). By applying manual pressure to raise brake lever  64 , camming lug  236  is raised over forward facing abutment surface  248  and returns to the neutral position shown in  FIG. 22 . Thus, the sliding movement of camming lug  236  over forward facing abutment surface  248  provides an over-center action to lock and unlock brake lever  64 . The upward motion of brake actuator  210  between the neutral and lock or “park” positions is transmitted to rear wheel brake shoes  66 , as described below. 
   As is evident from the foregoing description, the user can apply and release a braking force to the rollator by pulling up and releasing brake lever  64 , and can apply a constant braking force by pushing brake lever  64  down into the locked or “park” position. 
   Referring now to  FIG. 25 , the manner in which the upward motion of brake actuator  210  is transmitted to rear wheel brake shoe  66  is shown. Brake actuator  210  is bolted in the upper end of telescopic tube  52  as described above. Telescopic tube  52  is slidably received inside rear leg member  16 . Rear leg member  16  is fixedly attached to fixed rear leg bracket  26  in a manner that leaves the inside volume of rear leg member  16  open to permit telescopic tube  52  to slide therein. For example, bosses having threaded sockets can be provided on the outer surface of rear leg member  16  and corresponding keyway can be formed in fixed rear leg bracket  26  to receive such bosses. Leg  16  and bracket  26  can then be secured by bolting through an aperture in the keyway into the threaded sockets. 
   Telescopic tube  52  is provided with a series of evenly spaced holes  254  along a portion of its length. Fixed rear leg bracket  26  has a transverse bore  256  formed in each side, with the inner bore being internally threaded to receive the threaded end of thumb screw  54  (see  FIG. 1 ). Handgrip assembly  50  may be fixed at the desired height by aligning a selected hole  254  in telescopic tube  52  with bore  256  in bracket  26 . Thumb screw  54  is inserted into the outer bore  256  of bracket  26 , through the selected hole  254  in telescopic tube  52 , and is screwed into the threaded inner bore  256  on the opposite side of bracket  26 . 
   This arrangement provides for a secure manner of adjustably attaching handgrip assembly  50  to the fixed rear leg bracket  26  of the walker. The use of thumbscrew  54 , which passes entirely through telescopic tube  52  and is threaded into the opposite side of bracket  26 , distributes the load applied by the user on handgrip assemblies  50  evenly across bracket  26 . This is a far more durable means of attachment than that one which merely secures the telescopic tube by a thumbscrew, which passes through one wall of the bracket and squeezes against the outer surface of the telescopic tube. A solid attachment between the telescopic tube  52  and bracket  26  is extremely important not only for reasons of durability and safety, but also because of the sense of security imparted to the user. Users are far less willing to accept a walker if the handgrip assemblies feel loose or flimsily mounted. While the through-bolt arrangement of thumbscrew  54  does offer enhanced durability, it does require a special arrangement to permit brake actuation internally within telescopic tube  52 . 
   Referring to  FIG. 25 , a brake wire  250  is formed in an inverted “U” shape with a bight at an upper end thereof being retained in groove  252  formed in the cylindrical portion  214  of actuator  210 . Downwardly extending legs  258  and  260  of the brake wire  250 , which form a gap therebetween, are attached to the brake rod  262  by means of a clamp  264 . The brake rod  262  is an elongated “U” shaped channel member. 
   Referring to  FIG. 26 , clamp  264  has back surface  268  and side surfaces  270 , which are sized to be closely received in the “U” channel of brake rod  262 . Recesses  272  are provided to accommodate downwardly extending legs  258  and  260  of brake wire  250 , and teeth  274  are formed in recesses  272  to grip brake wire  250 . The clamp  264  is drawn tight against the upper end of the brake rod  262  by means of an Allen screw  266 , whereby the teeth  274  trap and secure the brake wire  250  against the brake rod  262 . The Allen screw  266  is axially aligned with the first hole  254  in the telescopic tube  52  above bracket  26  permitting a wrench or key to be inserted therethrough for the purpose of loosening or tightening clamp  264 . The brake wire  250  can advantageously be formed of wound steel piano wire, e.g. 0.09 inch diameter, as the ridged surface thereof can be securely gripped by the teeth  274 . 
   Elongated slot  276  is formed in the center web of brake rod  262 . Thumbscrew  54 , which is threaded into transverse bore  256 , passes through slot  276 . Slot  276  is sized as to permit brake rod  262  to be displaced longitudinally by the upward and downward movement of brake actuator  210  without contacting thumbscrew  54 . 
   In order to adjust the height of handgrip assemblies  50 , a key or wrench is inserted through hole  254  above bracket  26  and Allen screw  266  is loosened to permit relative longitudinal movement between the brake wire  250  and the brake rod  262 . The thumbscrew  54  is then unscrewed and withdrawn from the transverse bore  256 . The telescopic tube  52  is then raised or lowered until the desired hole  254  is axially aligned with the transverse bore  256  and the thumbscrew  54  is reinserted and tightened to secure telescopic tube  52  in bracket  26 . Finally, Allen screw  266  is tightened to secure the brake wire  250  to the brake rod  262 . 
   Referring to  FIG. 27 , rear fork assembly  44  comprises inner and outer fork housings  280  (only one of which is shown in  FIG. 20 ) between which the rear wheel  42  is mounted for rotation about the axle  282 . Rear fork assembly  44  is attached to rear leg member  16  by means of through-bolts (not shown), which pass through holes  283  in the fork housings and rear leg member  16 . Brake shoe  66  is pivotally mounted on shaft  284 , which is transversely secured between fork housings  280 . Brake rod  262  is connected at its bottom end to the brake shoe  66  at pivot point  286 . Elongated slot  288  is provided in the centre web of brake rod  262  to permit the through-bolts to pass therethrough and is sized to permit brake rod  262  to be displaced longitudinally by the upward and downward movement of brake actuator  210  without contacting the through-bolts. Spring  290  is retained between lug  292  and housing  280  and biases brake shoe out of engagement with rear wheel  42 . 
   Referring to  FIGS. 28 to 30 , the details of brake shoe  66  can be more readily seen. Brake shoe  66  has a horizontally disposed upper surface  294  and vertical sidewalls  296 , which together bound a downwardly open cavity. Friction member  294  is carried within said cavity and is attached thereto at point  300 . Friction member  294  has downwardly protruding tang  302  at its rearward end. Adjusting screw  304  is threaded through the upper surface  294  of brake shoe  66  and contacts the upper surface of friction member  294 . The extent to which tang  302  protrudes below brake shoe  66  can be varied by turning adjusting screw  304  in or out. This adjustability permits fine-tuning of the braking action and compensates for tire wear. 
   When brake rod  262  is moved upwardly by the operation of brake lever  64 , brake shoe  66  is caused to pivot about shaft  284  forcing tang  302  downward into frictional engagement with rear wheel  42 . When brake lever  64  is released and returns to its neutral position, brake rod  262  moves downwardly and brake shoe  66  pivots out of frictional engagement with rear wheel  42 . In this manner, braking action is transmitted from the brake lever  64  to the brake shoe  66  internally of telescopic tube  52  and rear leg member  16 . 
   An alternative embodiment for a height adjustable brake according to the present invention is illustrated in  FIGS. 31 to 36 , and includes an upper brake leg  410  slideably receiving a lower brake rod  411 . The cylindrical portion  214  of brake actuator  210  is fixed to an upper end of the upper brake leg  410  by fastener  412 . The lower end of the upper brake leg  410  receives the upper end of the lower brake rod  411 . A lock button  413  is spring biased outwardly through a hole  414  in the upper end of the lower brake rod  411  by a spring  416  for adjustably connecting the lower brake rod  411  to the upper brake leg  410 . An elongated groove  418  extends through the wall of the upper brake leg from the lower end to the upper end thereof for slideably receiving the lock button  413 . Channels  419  extend perpendicularly from the groove  418  providing several resting places for the lock button  413  defining a plurality of positions corresponding to different predetermined heights of the handgrip assemblies  50 . The lower end of the lower brake rod  411  is connected to the rear fork assemblies  44  by a bolt  420 , which extends through an opening  421 . A spacer bushing  423  surrounds the bolt  420  providing a smooth bearing surface enabling the lower brake rod  411  to rotate slightly about a longitudinal axis thereof during height adjustment. The opening  421  has a diameter slightly larger than an outer diameter of the spacer bushing  423  to facilitate relative rotation. The slight twisting of the lower brake rod  411  enables the lock button  413  to disengage from one of the channels  419  during adjustment. A coil spring  424 , surrounding the spacer bushing  423 , spring biases the lower brake rod  411  to the normal use position, i.e. biases the lock button  413  back into one of the channels  419 . 
   During height adjustment, as the lock button  413  engages one of the channels  419 , elongated slots  426  in opposite sides of the lower brake rod  411 , forming gaps therein, become aligned with one of a series of elongated apertures  427  in the upper brake leg  410  for receiving the thumb screw  54  or some other locking bolt, rod or pin. Accordingly, the thumbscrew  54  extends all the way through the fixed rear leg bracket  26 , the telescopic tube  52 , the lower brake rod  411  and the upper brake leg  410  providing a secure locking feature between the fixed rear leg bracket  26  and the telescopic tube  52 , while providing reciprocal movement of the lower brake rod  411  and the upper brake leg  410 , enabling actuation the brake levers  64 . Moreover, the thumbscrew  52  ensures that the upper brake leg  410  does not rotate relative to the lower brake rod  411 , thereby disengaging the lock button  414  from the selected channel  419 . 
   While the present invention has been described with reference to the embodiments disclosed in the Figures, it will be understood that variations and modifications may be made without necessarily departing from the scope of the invention. Accordingly, the scope of the invention is to be determined in accordance with the claims appended hereto.