Patent Publication Number: US-6666222-B1

Title: Rolling walker adapted to negotiate uneven surfaces

Description:
CROSS REFERENCE 
     This application claims the benefit of Disclosure Document No. 487548 filed Jan. 22, 2001. 
     BACKGROUND OF THE INVENTION 
     This invention relates to an improved walker for use by persons having physical disabilities. 
     More specifically, this invention relates to an improved and safer walker having wheel assemblies that can traverse rough surfaces and roll over small obstacles without wheel drag. 
     Walkers are commonly used as a support by many of the frail aged and other persons with physical disabilities while they are moving from place to place. One typical walker in use today consists of a generally rectangular, tubular frame having four legs and open at the rear. In some variations of that walker design, all four legs terminate in caps or buttons that slide along or otherwise engage the floor or other walking surface. The invalid walker described in U.S. Pat. No. 4,135,535 is of such design, 
     In another design variation, the two front walker legs are provided with wheels while the floor engaging ends of the rear legs terminate in a cap or button that slides along the floor or other surface as the user moves with the walker. The rear legs of this walker design tend to catch on minor surface irregularities and require the user to lift the rear of the walker to advance it, a task that often is difficult for many users. One approach to solving that problem has been to provide wheels on the rear walker legs as well as on the front. A full-wheeled walker is easier for a user to advance but also tends to be less stable, particularly when the user attempts to use the walker to aid or regain balance. That instability problem, in turn, has promoted efforts to provide a variety of braking systems that either act upon one or more of the walker wheels or rely upon an appendage to contact and drag along the floor or other walking surface. Examples of full-wheeled walkers that also incorporate a braking system include those described in U.S. Pat. Nos. 4,765,355, 5,020,560 and 6,068, 273. A large variety of rolling (wheeled) walkers are available on the market today. Some are four wheeled and some are three wheeled. Many are adjustable in a variety of fashions and they include all kinds of features, such as baskets, bags, seats and brakes. Many of them fold for easy transportation. As can be appreciated, addition of baskets, bags, seats, brakes and the ability to fold increases greatly increases the cost. 
     None of the prior art walkers provide wheel means that can smoothly traverse small obstructions such as carpet edges, elevator doorways electrical cords, twigs and small branches, gravel, sidewalk irregularities and the like. This invention fills those needs. 
     Development of a rotating walker which can smoothly traverse small obstructions such as carpet edges, elevator doorways electrical cords, twigs and small branches, gravel, sidewalk irregularities and the like represents a great improvement in the field of walker designers and satisfies a long felt need of the disabled public. 
     SUMMARY OF THE INVENTION 
     The present invention is an improved rolling walker of the type having a frame, and a leading wheel, which has a low point, rotatably attached to the bottom of the frame at its front. The improvement comprises an intermediate wheel, which is rotatably attached to the bottom of the frame, close to and behind the leading wheel so that the low point of the intermediate wheel is lower than the low point of the leading wheel. Preferably the distance between the wheels is about ¼ inch and difference between the low points is also ¼ inch. 
     One way of making the low point of the intermediate wheel lower than the low point of the leading wheel is to make the axle of the intermediate wheel lower than the axle of the leading wheel. Another way of making the low point of the intermediate wheel lower than the low point of the leading wheel is to keep the axles at the same height but make the diameter of the intermediate wheel larger than the diameter of the leading wheel. 
     Hence, it is an object of this invention to provide a walker that rolls easily over small obstacles and is more maneuverable than are walkers of conventional design. 
     Other objects and advantages of this invention will become evident from a study of the following description and accompanying drawings. 
    
    
     An appreciation of the other aims and objectives of the present invention and an understanding of it may be achieved by referring to the accompanying drawings and description of a preferred embodiment. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a three dimensional diagram of a four wheeled rolling walker adapted to negotiate uneven surfaces accordance with this invention. 
     FIG. 2 is a three dimensional view of a prior art three wheeled rolling walker 
     FIG. 3 is an enlarged view of the area indicated at  3  on FIG. 1, which illustrates making the axle of the intermediate wheel lower than the axle of the leading wheel. 
     FIG. 4 illustrates the alternate method to that shown on FIG. 3 of keeping the axles at the same height but making the diameter of the intermediate wheel larger than the diameter of the leading wheel. 
     FIG. 5 illustrates a bogey with a leading and intermediate wheel for replacement of the front wheel assembly of a three wheeled walker. In this bogey the axle of the intermediate wheel lower the axle of the leading wheel. 
     FIG. 6 illustrates an alternate embodiment bogey with a leading and intermediate wheel for replacement of the front wheel assembly of a three wheeled walker. In this bogey the axles are at the same height but the diameter of the intermediate wheel is larger than the diameter of the leading wheel. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     While the present invention is described herein with reference to illustrative embodiments for particular applications, it should be understood that the invention is not limited thereto. Those having ordinary skill in the art and access to the teachings provided herein will recognize additional modifications, applications, and embodiments within the scope thereof and additional fields in which the present invention would be of significant utility. 
     FIG. 1 shows a wheeled rolling walker  10  which has been modified to negotiate uneven surfaces in accordance with this invention. All walkers  10  have a frame  14  with legs  18 . They can be considered to have a front  22 , a rear  26  and a bottom  30 . They are made so that a person can enter the confines of the walker  10  from the rear  26  and grip the handles  34 . The walker  10  illustrated on FIG. 1 has four legs  18 . At the bottom  38  of each leg  18  is affixed a wheel  42 ,  44  on an axle  46 . In other words there are two wheels  42  attached to the rear  26  of the frame  14  at its bottom  30  and two leading wheels  44  attached to the front  22  of the frame  14  at its bottom  30 . Each leading wheel  44  has a low point  50 . In prior art walkers this is the point on the wheel that contacts the ground. What has been described so far is no different from many rolling walkers on the market today. The problem with this type of walker is that it must be raised if the user encounters rough surfaces or small obstacles. 
     What distinguishes this walker  10  from other prior art walkers is a pair of intermediate wheels  54  attached on axles  42  behind the leading wheels  44 . While these intermediate wheels  54  are attached between the leading  44  and rear  42  wheels, they are preferably close to the leading wheels  44 . They should, preferably be attached so that there is at least ¼ inch but no more than a few inches between the leading  44  and intermediate  54  wheel. The intermediate wheels  54  are attached so that their low points  58  are lower than the low points  50  of the leading wheels  44 . Preferably this difference in height  62  is ¼ inch. 
     There are at least two ways of accomplishing this difference in height  62 . See FIGS. 3 and 4. One way is use wheels  44 , 54  of the same diameter  64  but make the axle  46  of the intermediate wheel  54  lower, by the same distance  62 , than the axle  46  of the leading wheel  44 . This is illustrated in FIG.  3 . The other way is to keep the axles  46  at the same height but use an intermediate wheel  54  with a diameter  66  greater than the diameter  64  of the leading wheel  44 . The necessary diameter of the intermediate  54  wheel is easy to calculate from elementary geometry. 
     In either case, having two pairs of wheels  44 ,  54 , close together, with a small difference  62  in their low points  50 ,  58  allows rolling walkers  10  made in accordance with this invention to smoothly traverse small obstructions such as carpet edges, elevator doorways electrical cords, twigs and small branches, gravel, sidewalk irregularities and the like. The intermediate wheel  54  will usually contact the ground at its low point  58  and the leading wheel  44  will roll over small obstructions as they are encountered, thus increasing the stability of the walker  10 . 
     From the above description it will be seen that the inventive novelty of the rolling walker  10  of this invention is provision of two pairs of wheels  44 ,  54 , close together at the bottom of  30  front  22  of the walker  10 , with a small difference  62  in low points. Thus this inventive novelty can be applied to any prior art rolling walker. All that may be required is a special attachment bracket. Design and construction of such brackets are well known in the field of mechanical inventions. 
     This invention can, therefore, be applied to three wheeled walkers. A prior art three wheeled walker  10  is illustrated in FIG.  2 . This particular design includes brakes  78  and a basket  82 . The front wheel assembly  86 , which includes the leading wheel  44  may be rotatable in the horizontal plane to ease steering of this walker  10 . Bogeys  90  for replacement of this front wheel assembly  86  are illustrated in FIGS. 5 and 6. On FIG. 5 the wheels  44 ,  54  are the same diameter  64  but the axle  46  of the intermediate wheel  54  is lower than the axle  46  of the leading wheel  44 . On FIG. 6 the axles  46  are at the same height but the diameter  66  of the intermediate wheel  54  is greater than the diameter  64  of the leading wheel  44 . Again, the necessary diameter of the intermediate  54  wheel is easy to calculate from elementary geometry. The ascending member  94  is designed to attach to the frame  14 , rotatably if desired. 
     The following reference numerals are used on FIGS.  1  through  6 : 
       10  Rolling walker 
       14  Frame of rolling walker 
       18  Leg of rolling walker 
       22  Front of frame 
       26  Rear of frame 
       30  Bottom of frame 
       34  Handle 
       38  Bottom of leg 
       42  Rear wheel 
       44  Leading wheel 
       46  Axle 
       50  Low point of leading wheel 
       54  Intermediate wheel 
       58  Low point of intermediate wheel 
       62  Difference in point of contact and difference in heights of wheels and difference in heights of axles 
       64  Diameters of leading and intermediate wheels in case where diameters are equal 
       66  Diameter of intermediate wheel in case where diameter of intermediate wheel is larger than the diameter of the leading wheel 
       78  Brake 
       82  Bag 
       86  Front wheel assembly 
       90  Bogey 
       94  Ascending member 
     Thus, the present invention has been described herein with reference to a particular embodiments for a particular applications. Those having ordinary skill in the art and access to the present teachings will recognize additional modifications, applications and embodiments within the scope thereof. 
     It is therefore intended by the appended claims to cover any and all such applications, modifications and embodiments within the scope of the present invention.