Abstract:
A crutch constructed of two adjacently located, elongated, parallel upper and lower bows which can be moved in relationship to each other to form a vertical support of readily varied length. These bows have the same design and are therefore interchangeable, significantly reducing inventory requirements. Each bow has a series of parallel horizontal notches with the bows positioned so that the notches on each bow are on contacting surfaces. A pin inserted into parallel, adjacent notches on the two bows in cooperation with two or more collars or caps on the ends of one end of each bow fixes the relationship between the shafts which, in turn, defines the length of the vertical support. A similar concept can be used to lock a moveable centrally located lower bow between two parallel outer upper bows. This assemble provides a strong, adjustable length crutch for any height patient using only two different pairs of bow lengths.

Description:
[0001]    The present invention relates to a new structure for assembling a crutch having a easily adjusted length and grip height.  
         BACKGROUND  
         [0002]    Crutches, fabricated from wood or metal (usually aluminum) tubes, have been used as an aid to assist injured or disabled individuals in standing or walking. While there are numerous design variations, a typical crutch has a “Y” frame design with two upper members or bows which converge at a lower end where a central leg is formed or attached. The upper ends of the upper members extend vertically upward from the point of convergence and parallel to each other but spaced apart. An underarm support brace is attached across the upper ends of the bows. A horizontal hand grip is mounted between the upper members or bows at an arms length or slightly less than an arms length from the under arm brace.  
           [0003]    In order to adjust the length of the wooden crutch to various height individuals the two bows of the crutch usually have one or two holes there through below where the upper members converge. This hole or holes receives a bolt which also passes through one of several horizontal holes along the length of the central leg or foot piece. Once a hole in the leg is selected to provide a crutch of the proper length the bolt is secured by applying a nut to the bolt. In a like manner, the hand grip is attached between the upper members at a proper height by placing a bolt or pin through the hand grip and one of several pairs of horizontal holes in the upper members.  
           [0004]    When the crutch is constructed from metal tubes the central leg is usually telescoped within an upwardly extending tube with the adjustment accomplished by use of an internal spring biasing a pin through aligned holes in both the lower central tube and the upwardly extending tube.  
           [0005]    A further alternative approach has the hand grip extending at a 90 degree angle from an upper bow.  
           [0006]    With the crutches presently available, assembly of the crutch with proper dimensions, namely the length from lower tip to under arm support and hand grip location, for each different individual is difficult. Further, use of a screw driver and wrench or pliers is required to assemble, disassemble and reassemble the crutch. This procedure is time consuming and typically requires several attempts until the crutch is properly sized for the comfort and safety of each particular user. Also, because of limited length adjustability four or five different length crutch assemblies must be inventoried.  
           [0007]    U.S. Pat. No. 4,917,126 to Ellmore shows a crutch comprising adjacent tubes secured together in a parallel manner using an upper and lower clamp. An upper tube is telescopically mounted in a first central tube with an underarm support attached to the top end. A lower tube telescopically mounted in a second central tube has a tip on its lower end. A handgrip is clamped to a central tube. The length (height) of the crutch is adjusted by extending the upper and lower tubes. The position of these tubes in the outer tubes is fixed by using a series of holes in the outer tube and a spring loaded plunger located within the inner tube. U.S. Pat. No. 4,846,203 to Tappel shows a similar construction with the exception that the centrally located outer tube is a single tube with two parallel holes.  
           [0008]    U.S. patent 869,128 to Autenreith shows a crutch comprised of two parallel adjacently located tubes with a coupling attached to the lower end of the upper tube so as to receive the lower tube in a sliding manner. Extending from the bottom of the upper tube is a shaft which is captured in a sleeve mounted to the lower tube. The position of the shaft in relation to the upper and lower tubes is fixed using set screws.  
           [0009]    U.S. Pat. No. 5,349,977 to Wood shows a crutch or walker with two parallel tubes with one tube having a roughened surface. The position of the two tubes in relationship to each other is fixed through the use of a pivoting piece.  
           [0010]    U.S. Pat. No. 1,254,771 to Brown shows a portable bath house with adjustable length uprights comprising two parallel pieces. The lower piece has two collars through which the upper piece slides. Attached to the lower piece is a spring mounted bolt which slides in a hole in the first piece and sets in one of a series of holes on the second piece.  
           [0011]    U.S. Pat. No. 1,888,972 to Chittim also shows two piece adjustable tent poles. The lower piece has an attached collar through which the second piece attaches. Also attached to the top of the first piece is a pivoting link The link includes a traverse pin which sets in a notch on the upper bar. This arrangement prevents the pole from shortening but does not prevent lengthening, thus making it an arrangement unsuitable for a crutch. U.S. patent 208,158 to Cushing and U.S. patent 35,963 to Warner and Palmer show other extendable tent poles.  
           [0012]    There are numerous other patents, of which U.S. Pat. No. 5,139,040 and U.S. Pat No. 5,752,535 are examples, that show crutches constructed of telescoping tubes with a series of holes and spring mounted pins for adjustment. In addition, there are numerous patents that use bolts and other more permanent assembly means.  
           [0013]    U.S. Pat. No. 5,351,701, U.S. Pat. No. 5,402,811, U.S. Pat. No. 5,445,175 and U.S. Pat. No. 5,765,583 are representative of adjustable designs with two upper shafts and one lower shaft. These designs all appear to have the same type of fixturing for adjusting the extension of the lower leg, namely screws, bolts or spring pins  
         BRIEF DESCRIPTION OF THE INVENTION  
         [0014]    The invention is directed to a crutch comprising two adjacently located, elongated, parallel shafts which can be moved in relationship to each other to form a vertical support of readily varied length. Each shaft has a series of parallel horizontal notches with the notches on each shaft positioned on contacting surfaces of the shafts. A pin inserted into parallel, adjacent notches on the two shafts in cooperation with two or more collars or caps fixes the relationship between the shafts which, in turn, defines the length of the vertical support. A similar concept can be used to lock a moveable centrally located shaft between two parallel outer shafts. These shafts are all held in their adjacent orientation by caps mounted on one end of each shaft with the second shaft slideable there through. This assemble provides a strong, adjustable length crutch from only two different pairs of bow lengths. Further, the upper and lower bow have the same design and are therefore interchangeable, significantly reducing inventory requirements. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]    [0015]FIG. 1 shows a side view of a first embodiment of an adjustable crutch incorporating features of the invention.  
         [0016]    [0016]FIG. 2 shows the upper and lower bows of the crutch of FIG. 1 with round pin openings.  
         [0017]    [0017]FIG. 3 is a top view of one version of a pin used to hold the upper and lower bows in fixed relationship.  
         [0018]    [0018]FIG. 4 is a side view of a version of a pin used to secure the handle to the crutch.  
         [0019]    [0019]FIG. 5 is an end view of the pin of FIG. 4.  
         [0020]    [0020]FIG. 6 is a top view of a cap which is mounted to the top end of the lower bow of the crutch for slideably retaining the upper bow.  
         [0021]    [0021]FIG. 7 is a cutaway side view of the cap having the same construction as shown in FIG. 6 for attachment to the lower end of the upper bow for slideably retaining the lower bow.  
         [0022]    [0022]FIG. 8 is a partially cutaway side view of a second embodiment of showing the lower portion of a crutch incorporating features of the invention.  
         [0023]    [0023]FIG. 9 is a side view of a fork shaped pin used to fix the adjustable lower bow to one of the upper bows of the crutch.  
         [0024]    [0024]FIG. 10 is a top view of a collar used to hold the assembly of FIG. 8 together in a sliding arrangement.  
         [0025]    [0025]FIG. 11 is a perspective side view of a central portion of a further version of the bow of an extendable device incorporating features of the invention.  
         [0026]    [0026]FIG. 12 is a side view of a further version of a pin used to assemble the bows of the device.  
         [0027]    [0027]FIG. 13 is a cross section view taken along line  3 - 3  of FIG. 1 showing a pin in a pair of notches.  
         [0028]    [0028]FIG. 14 is a cross sectional view taken along line  4 - 4  of FIG. 1 showing the pin of FIG. 4 inserted in the hand grip.  
         [0029]    [0029]FIG. 15 is a top view of an alternative collar or bracket for use in the embodiment of FIG. 8.  
     
    
     DETAILED DESCRIPTION  
       [0030]    The crutch  10  uses a new method of construction and assembly. Referring to FIG. 1, a first embodiment of the crutch  10  comprises two straight bows (a lower bow  12  and an upper bow  14 , which are positioned in parallel relationship next to each other with a portion of each extending beyond the end of the other bow. While designated as lower bow  12  and upper bow  14 , it should be recognized that the lower and upper bows  12 ,  14  can be of exactly the same construction as they are interchangeable in the described design. An underarm support  16  is attached to the top of the upper bow  14 . A tip  18  is attached to the bottom of the lower bow  12 . A collar  20 , shown in FIG. 6, is secured to the top end of the lower bow  12 . The collar  20  has an opening  22  therein to receive the upper bow  14 , the upper bow  14  being free to slide up and down in the opening  22  unless secured as discussed below. In a like manner, a similar lower collar  24 , shown in FIG. 7 receives the lower end of the upper bow  14  in a closed bottom portion  37  where it is secured by a screw, pin or barb  35  so that the upper bow  24  is fixed but the lower bow  12  is free to slide up and down. The upper collar  20  also has an area for receiving a bracket  28  with pin  30 , described below, which secures the crutch  10  at its desired length. A hand grip  40  is mounted approximately midway along the length of the crutch  10 . The shape of the underarm support  16  and the hand grip  40  shown in the drawing are merely for illustrative purposes. Any suitable shaped support  16  or grip  40  known to those skilled in the art may be attached to the crutch  10 .  
         [0031]    As shown in FIG. 1, and the enlarged view in FIG. 2, both the upper bow  14  and the lower bow  12  have a series of notches  26  along the length of a portion thereof. FIG. 2 shows the notches  26  to be semicircular; FIG. 1 shows them to be rectangular. Any of a variety of shapes can be used. FIG. 3 shows a bracket or clip  28  with a centrally located pin  30  of a shape and size to simultaneously fill adjacent notches on both bows  12 , 14 . For example, if the notch  26  is a semicircle on each bow  12 ,  14 , the pin  30  is a circular shaft of about the same radius. If the notches  26  are rectangles then the pin  30  is a shaft with a cross section approximately the size of paired notches on the upper and lower bows. The clip  28  also has wings  32  sized to fit across the width of the collar  20 , with inwardly facing barbs  33  latching on the rear side thereof so as to be held in position once the pin is inserted through the collar and into the notches  26 . FIG. 13 is a cross sectional view showing a clip  28  inserted into adjacent parallel notches  26 . FIG. 14 is a cross sectional view showing a half pin  42  inserted into the handle  40  filling the notch on only the upper bow  14 .  
         [0032]    To assemble the crutch the lower and upper bows  12 ,  14  are inserted into the collars  20 ,  24  and the handle  40 , the underarm support  16  is attached to the upper bow  14  and the length is adjusted so that a notch  26  on each bow  12 ,  14  is adjacent by sliding the bows parallel to each other to a length appropriate for the user&#39;s height. The clip is then placed over, and snapped on to, the upper collar  20  with the pin  30  through the matching notches  26  now aligned with the hole  34  in the collar  30 . This procedure locks the assembly in its desired length. Alternatively, the clip  28  could be inserted in to any pair of notches or more than one clip could be used.  
         [0033]    The handle  40  is secured at the desired height by using a pin  42  of a cross section matching a notch, but not the two parallel notches. As shown in FIGS. 4 and 5, and inserted in FIGS. 2 and 14, the pin  42  has a cross section to match a notch  26  as shown in FIG. 2. This allows the length of the crutch to be adjusted independent of the handle  40  without disconnecting the handle.  
         [0034]    Crutches are composed of several components assembled into a structure sized for the intended user. In order to provide a crutch of prior dimensions, formed from wood or aluminum, four or five different length assemblies are generally required to provide a selection of crutches to meet the need of various height individuals. For example, four different size adjustable crutches are usually necessary to provide crutches for a typical child and adult population, requiring the stocking of a considerable inventory of crutches to meet patient needs. These sizes are typically a crutch adjustable from a) 29 inches to 38 inches (29″-38″) for a child 3 foot, 9 inches to 4 foot, 7 inches (3′9″-4′7″), b) 37″-45″ for a youth 4′6″-5′2″, c) 44′-52″ for an adult 5′1″-5′9″, and d) 52″-60″ for a tall adult 5′10″-6′6″. A typical prior art wooden crutch requires five different size crutches to cover the same range of patients. As is apparent, since prior crutches have different shaped upper and lower bows, not only must many sizes be inventoried, different top and bottom components must also be stored.  
         [0035]    Crutches incorporating features of the invention, because of their ease of assembly, can provide a broader size range with only two size combinations of upper bow  14  and lower bow  12 . Further, because of the design of the product, the upper and lower bow can be of exactly the same length, appearance and construction. While the length of the standard components may be varied, in a preferred embodiment a crutch for an adult 5′5″ to 7′4″ may be assembled from two bows  12 , 14 , which are of the same length, and are interchangeable, about 42″±2″ long, to which a standard underarm support  16 , tip  18  and hand grip  40  is attached. In the same manner, a crutch for shorter individuals (3′9″-5′8″) would be constructed from lower and upper bows  12 ,  14  about 30″ long. This provides a single crutch, with 42″ bows which is adjustable for use by 50 to 70% of the using public.  
         [0036]    [0036]FIG. 8 shows a second embodiment of the crutch  100  having two upper bows  114 ,  115  and one centrally located lower bow  112 . Notches  126  function in the same manner to receive a full width clip  128 , shown in FIG. 9 to secure the centrally located lower bow or foot piece  112  to a notched upper bow  114 . In this embodiment, the clip  128  has two barbed pins  130  which are placed in two sets of vertically spaced but adjacent notches  126 . In the same manner as described above, a half width barbed clip  128  can be used to secure a handle. Collar  124 , partially cut away in FIG. 8 shows the lower end of upper bow  115  retained by barbed extensions  136  on the inner surfaces of the collar  124 . A similar structure also retains the lower end of the other upper bow  114  in the collar  124 . FIG. 10 is a top view of a band  140  sized to receive the three bows midway along their length, the band having two inwardly extending half pins  142  which rest only in the notch  126  of the notched upper bow  114 . An under arm support and a hand grip (not shown) can be added in the same manner as shown for the first embodiment. This embodiment utilizing two upper bows provides for conversion of current production of three member crutch construction to use of the adjacent horizontal notch adjustment. FIG. 15 is a top view showing an alternative construction of a band  240  which has 3 bow receiving areas  242 ,  244 ,  246  to receive the three bows  112 ,  114 ,  115  and maintain them spaced apart for easier adjustment, the receiving areas  242 ,  244 ,  246  being separated by webs  248 . The collar  124  would have a similar spacing and web construction.  
         [0037]    While the above description is primarily directed to the construction of a crutch, it should be recognized by one skilled in the art that the concept has much broader application. It can be used to form a broad variety of support structures which are desirably adjustable in length. Examples are canes, tent poles, book case shelf supports, light poles, etc. For such applications and to provide more length adjustment options FIG. 11 shows a shaft  200  with a square cross section and notches  226  on all four sides in a stepped spiral pattern. This provides, when matched with a second notched, square cross section rod (not shown), an upright support infinitely adjustable in length. The second notched rod may be the same as in FIG. 11 or may have a series of notches on only one side as shown in FIG. 1 or  2 . Only a short notched section is shown. However, it is contemplated that this structure be continuously repeated along the length of the bow  200 . FIG. 12 shows an example of a split pin  228  for use in locking the shaft  200  to a second shaft. One or more collars such as shown in FIG. 10 are utilized to hold the shaft  200  to the second notched shaft. This bow construction provides greater length adjustment accuracy in a crutch, and because the notches are on all four sides, provides for a wide variety of hand grip attachment techniques with pins both parallel and perpendicular to the handle axis.  
         [0038]    While the crutch design shown and described is intended for the assembly of wooden crutches, any stiff, structural material can be used for the bows including metal shafts, tubes and rods as well as composite materials. Also, while rectangular and square cross sections are shown, one skilled in the art will recognize that any cross section may be used for the bows as long as the notch with locking pin arrangement is utilized. It is also contemplated that features in one embodiment may be incorporated in the other embodiments.  
         [0039]    It is evident from the foregoing that there are many additional embodiments of the present invention that, while not expressly described herein, are within the scope of this invention and may suggest themselves to one of ordinary skill in the art. It is therefore intended that the invention be limited solely by the appended claims.