Abstract:
A brake system for a wheeled walker frame having two walker frame legs with two telescopically adjustable frame tubes, of which one frame tube supports in its upper region a handle and a brake lever and the other is provided in its lower region with a brake device for braking a wheel. A telescopically adjustable brake rod is disposed within the frame tubes, between the brake lever and the brake device, and includes two parallel rods of which one is interconnected with the brake lever and the other is interconnected with the brake device. An axial longitudinal adjustment of the frame tubes to the desired vertical position synchronously causes a corresponding alteration of the length of the brake rod. At least one device is provided for locking the frame tubes and the parallel rods.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a brake system for a wheeled walker. 
     BACKGROUND OF THE INVENTION 
     Wheeled walker frames are normally constructed from metal tubing, which results in constructions which are stable, durable and relatively light. According to the legislation of most European countries, such a wheeled walker frame must satisfy certain requirements in order to be employed within public medical care. It should have as hygienic an exterior as possible, ie. clean, smooth surfaces, few dirt pockets and few projecting parts. It should further be provided with a brake for each handle which in turn must be capable of being adjusted in the vertical direction in as simple a manner as possible, in which event the adjustment of the brake should preferably take place synchronously, or employing very simple measures. A glance at prior art constructions shows that the transmission of the braking force from the handle to the brake substantially takes place via three principles: a) a flexible cable, b) a strap or lanyard of textile, or c) a metal rod, all disposed wholly or partly outside the metal tubing. These prior art brake systems suffer from drawbacks. The flexible cable forms loops which may catch in projecting objects such as handles on furniture. The same applies to the textile strap which must be adjusted after a movement of the handle, and also the metal rod located outside the tubing can catch in extraneous objects. For all three types, it is a common feature that they are unattractive and difficult to keep clean, which is of importance since wheeled walker frames are lent out to different patients during a period of convalescence, and therefore must be carefully cleaned before being passed on to the next user. 
     SUMMARY OF THE INVENTION 
     The object forming the basis of the present invention is to obviate or at least reduce the above outlined drawbacks inherent in prior art wheeled walker frames. 
     This object is solved according to the present invention. 
     The present invention makes possible the enclosure of the brake system in the frame tubing, which eliminates the drawbacks inherent in prior art wheeled walker frames with projecting parts and brake cables, etc. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Embodiments of the present invention will be described in greater detail hereinbelow, with reference to the accompanying drawings, in which: 
     FIG. 1 shows a section through one leg of a wheeled walker frame which has two telescopic tubes with lockable and extensible brake rods. 
     FIG. 2 a  shows a section through a part of one leg of a wheeled walker frame with a slightly deviating form of brake rod and locking device. 
     FIG. 2 b  shows a cross section through the leg of the wheeled walker frame with the parts in the displacement position. 
     FIG. 2 c  shows a similar cross section to FIG. 2 b , with the parts in the locked position. 
     FIG. 3 a  shows a longitudinal section through parts of a third embodiment, with the parts in the displacement position. 
     FIG. 3 b  shows a similar cross section to FIG. 3 a  with the parts in the locked position. 
     FIG. 4 a  shows a section through one leg of a wheeled walker frame according to yet a further embodiment, the brake rod being of the drawing action type. 
     FIG. 4 b  shows a section through a part of one leg of a wheeled walker frame with the parts in the locked position. 
     FIG. 4 c  shows a cross section through the parts of FIG. 4 b.   
    
    
     DETAILED DESCRIPTION 
     With reference to FIG. 1, an outer frame tube  10  constitutes, together with an inner frame tube  11 , carrying elements for a handle  12  and a brake lever pivotal about a shaft  15 , the handle being shown in three different positions, a braking position  13 , a neutral position  13   a  and a locked position  13   b . The brake lever is provided with a pressure surface  14  for contact with a spring-biased pressure plate  16  which is applied on the upper end of a rod  17   a  which constitutes the one component of an extensible brake rod  17 . The other component is a tube  17   b  in which the rod  17   a  runs and in whose lower end a brake device  18  in the form of a threaded pin is screwed in, the pin, on braking, being urged into abutment against a walker frame wheel  19  (partly shown on the Drawing). Since it should be possible to adapt a wheeled walker frame to both tall and short people, the handle must be capable of being raised or lowered and, after adjustment, be securely fixed in either position. To this end, there is provided, at the upper region of the outer frame tube  10 , an interiorly threaded aperture  110 , for example a sleeve nut in which a screw  111 , provided with a thumb wheel, may be twisted in and out. In the inner position, both of the telescopic frame tubes are mutually locked, since the screw has penetrated into one of the holes  112  which are stepwise punched out in the inner frame tube  11 . 
     A similar locking arrangement with sleeve nut  113  and screw  114  is mounted at the tube  17   b . When the screw  114  is threaded in, the rod  17   a  is clamped fast against the tube  17   b . The screw passes through an oval hole  115  punched in the outer frame tube  10 . The length of the hole is slightly greater than the diameter of the screw  114 , in order for the brake rod  17  in the locked position to be able to be pressed downward far enough for the brake device  18  to have a braking effect against the walker frame wheel  19 . 
     When the vertical position of the handle is altered, the procedure is as follows. Both of the screws  111  and  114  are backed off and threaded out so far that the telescopic units,i.e. the rods  17   a  and  17   b , as well as the frame tubes  10  and  11  are free and thereby mutually displaceable. The handle is raised or lowered until a suitable hole  112  in the frame tube  11  is in register with the screw  111 , which is then tightened into the hole  112 , thereby fixing the frame tubes to one another. Thereafter the screw  114  is tightened, so that the rod  17   a  is locked against the tube  17   b.    
     FIGS. 2 a, b, c  illustrate a slightly different version of the present invention. Here, the telescopic frame tubes are designated  20  and  21 . The mutual fixing in the vertical direction of these elements is the same as in the embodiment according to FIG. 1, i.e. a screw  211  runs in a sleeve nut  210 . The screw  211  is provided with a Stub shaft  216  which, on vertical fixing, passes through a hole  212  in the inner frame tube  21 . The brake rod  217  is, in this embodiment, composed of two rods  217   a  and  217   b  of square profile. The rods are axially displaceable in relation to one another and are locked at predetermined distances in that the rod  217   a  (in FIG. 2 a  the left-hand rod) is provided with a pin  214 . In the right-hand rod  217   b , there are provided slots  215  at the same distance and the same spacing as the holes  212  in the inner frame tube  21 . With the aid of the screw  211 , the stub shaft  216  is forced against the rod  217   a  which is, in such instance, displaced against the rod  217   b  and the pin  214  engages in the slot  215 . The rods are thereby axially fixed. A U-bent plate  213  ensures the lateral positioning of the rods. The locking of the adjustable parts thus takes place synchronously with the aid of the screw  211  provided with the thumb wheel, the stub shaft  216  and the pin  214 . 
     The procedure on adjustment of the vertical position of the handle is simple. The screw  211  is backed off as far as shown in FIG. 2 b , i.e. completely out of the hole  212 . Then, the pin  214  has, under the action of a spring  218 , released its engagement with the slot  215  and the rods  217   a  and  217   b  are axially displaceable in relation to one another. The height of the handle can therefore be adjusted and, by screwing in the screw  211 , the frame tubes are locked at the same time as the pin  214  enters into engagement with the slot  215 . The length and design of the stub shaft  216  are such that a certain radial play exists between the brake rod and the frame tube, in order for the brake rod to be displaced without excessive friction and without jeopardizing the braking function which, after all, presupposes a few millimetres&#39;vertical movement. 
     In the two described embodiments, the vertical positions of the handle were limited to a predetermined number. In the embodiment described below in connection with FIGS. 3 a  and  3   b , this adjustment is stepless. 
     The inner frame tube  31  is provided with a longitudinal slot  312  which is slightly longer than the total extent of the vertical adjustment. In the outer frame tube  30 , there is a hole  315  of the same diameter as the width of the slot  312 . The locking of the two frame tubes takes place by clamping between a nut  318  located within the inner frame tube, and a head disposed on the screw  311 , the periphery  320  of the head being toothed and constituting a grip for a thumb wheel or knob  319  which is rotatable about a shaft  316  journalled in a hole in the screw  311 . The free end of the shaft  316  is designed as a cross bit with whose help an arrest screw  321  can be rotated in a thread disposed in the tube  317   b  of the brake rod  317 . Since this, for reasons of weight, should be as thin-walled as possible, a socket  322  is disposed around the end of the tube and the thread is disposed for the greater part in this socket. Also in this embodiment, the locking of the adjustable parts takes place synchronously with the aid of the screw  311 , the shaft  316  and the arrest screw  321 . 
     The locking mechanism functions as follows. Starting from the locked position according to FIG. 3 a , the arrest screw  321  is first backed off so that the parts of the brake rod are released. Thereafter, the knob  319  is drawn outwards until it comes into engagement with the toothing  320  of the screw  311 . The screw can then be released and the clamping pressure ceases and the handle may be placed in the desired vertical position. The locking takes place most simply in the reverse sequence. First, the frame tubes are clamped together, the knob  319  is pressed in and the arrest screw is tightened so hard that the elements of the brake rod are locked in the axial direction. 
     The embodiments of the present invention described in the foregoing have a compression brake rod, to which the present invention is not restricted. The brake rod may also operate by a drawing action. Such a variation is illustrated in FIGS. 4 a - 4   c.    
     The brake lever,.which in the previously described examples, had a compression action on the brake rod must, in the present embodiment, act in the drawing direction instead. Thus, the brake lever  43  (see FIG. 4 a ) acts against a compression surface  46 , located above its pivot axis  45 , on an ear  49  which is connected to a rail  47   a  which in turn, together with a similar rail  47   b , forms the brake rod  47 . 
     The rails run in one another and can be mutually locked axially via a pin  416  disposed in the rail  47   b  and which engages in recesses  415  in the other rail  47   a . This engagement may take place when the rails are pressed together radially. The mechanism for this locking operation is similar to that illustrated in FIG. 2. A screw  411 , provided with a knob, is rotatable in a thread in a sleeve nut  410  fixedly welded to the outer frame tube  40 . Roughly halfway backed-off, the screw releases the contact with the inner frame tube  41 . The rails of the brake rod are then held apart under the action of a thin leaf spring  418 . The handle  412  may thus now be raised or lowered to the desired level. When the screw  411  is located in register with a hole in the inner frame tube, the screw is threaded in so far that the pin  416  is in engagement with a recess  415 . The length of the screw is adapted such that no radial “clamping pressure” occurs, but that a certain play exists when the screw is fully tightened. As a result, the brake rod is not impeded by friction in its movement, either between the screw and the rail or between the rail and the inner frame tube on braking. 
     Since the braking operation takes place by a drawing action, the brake device  420  is of a different concept than the previously described variations. The drawing force from the brake rod is transmitted via a drawing linkage  422  and a rocker arm  421  as compression force to the brake device. The advantage in a drawing action brake rod is that it may be permitted to be considerably more lightweight in dimensions than a compression action brake rod, since there is no risk of outward bending in a drawing action brake rod. Thus it is conceivable to manufacture the rails  47   a  and  47   b  of plastic.