Patent Publication Number: US-6216713-B1

Title: Support device having interchangeable tips

Description:
FIELD OF THE INVENTION 
     This invention relates generally to support or assistance devices such as canes, crutches, or walkers, and more specifically to support devices specifically adapted to be used on various types of surfaces. 
     BACKGROUND OF THE INVENTION 
     Mobility assisting devices such as canes, crutches, and walkers are used by many people on both temporary and permanent bases. Generally, such devices have tubular lower leg portions, having a rubber foot, or the like, disposed at the distal end. While these devices may be readily used during fair weather conditions, use of such devices is particularly difficult during inclement weather conditions. This is particularly true in snowy and icy conditions as the leg or legs may not maintain a firm footing. 
     Various modifications have been proposed to enhance the grip of such devices on slippery surfaces, with varying degrees of success. Examples of such proposals are disclosed in the following patents: U.S. Pat. No. 3,949,773 to Marescalco; U.S. Pat. No. 4,434,808 to Burak; U.S. Pat. No. 4,708,1154 to Edwards; U.S. Pat. No. 4,964,430 to Janis; U.S. Pat. No. 4,977,914 to Smerker; and U.S. Pat. No. 5,056,546 to Sharp. The devices disclosed in the Burak, Smerker, and Sharp patents disclose devices intended to provide retractable gripping arrangements. These devices are relatively complex, however, comprising spring-loaded extension/retraction arrangements which may be relatively expensive to manufacture and assemble. In addition, they are highly susceptible to breakage due to the a high number of moving parts. 
     The references to Janis, Marescalco, and Edwards each disclose tips having circular tip members with multiple teeth. The Janis and Marescalco references disclose a toothed gripping member constructed similarly to a circular hole saw. This circular arrangement of gripping teeth, however, can result in the bending and possibly breakage of one or more teeth as the user applies a force to the tip during usage, particularly when the force is applied in any direction other than absolutely normal to the ground. The cleat of Marescalco, which is stamped from a flat piece of metal and then the four toothed legs bent to a right angled position, is particularly susceptible to deformation during normal use. 
     Janis attaches the toothed gripping member to the shaft by a screws extending through the member and the shaft, or by a band which extends around the leg and likewise is tightened by screw arrangement. There is potential for the tip to slip from the leg in the case of the use of a band. In either arrangement, the coupling screw may not be readily tightened or loosened without a separate tool, rendering it difficult to utilize the toothed gripping member. Accordingly, Janis proposes an arrangement wherein two canes, for example, are coupled side by side, one being inverted. One of the canes would have a standard distal tip, while the other would have the toothed gripping member such that the user could utilize the appropriate cane for the environment. This arrangement can be expensive, heavy and cumbersome in that it requires the use of two support devices. Even in arrangements incorporating a single shaft with the different tips disposed at opposite ends, use of the device disposes the opposite, potentially soiled or sharp tip adjacent the user&#39;s limbs and/or body. 
     Marescalco attaches the cleat to the leg by coupling the cleat to the standard rubber elastomeric cup-shaped tip, which is removed from the leg for attachment of the cleat assembly, and then replaced on the leg. This may be reversed for removal of the cleat assembly. Alternately, a separate cup-shaped elastomeric tip may be placed over the cleat assembly to utilize the support device on a floor or finished surface. Elastomeric tips of this sort, however, are subject to degradation due to use or environmental conditions. The degradation of elastomeric cup-type tips is prevalent when such tips are repeatedly elastically or plastically deformed, as when the tip is removed or reassembled to the leg or the cleat. The elastomeric tip coupling the cleat assembly to the shaft is particularly susceptible to such degradation due to both environmental and use conditions. As a result, the relative positions of the cleat assembly and leg may shift during use, resulting in uncertain footing to the user and ultimate failure of the attachment. 
     The foot assembly of Edwards likewise will not provide firm footing to the user. The Edwards disk-shaped foot includes a pad having a plurality of somewhat rounded flexible, resilient fingers extending from its lower surface. Contrary to the representations made in Edwards, it is unlikely that resilient and flexible fingers such as this will provide firm footing on wet or icy surfaces. Further, an elastomeric material, such as would be used in the Edwards device, would not likely provide added traction over conventional elastomeric cup-type tips. 
     DMI DURO-MED Industries, Inc., of Hackensack, N.J., also markets a adapter which may be bracketed to the distal tip of a leg such that it may be unlatched and pivoted between a position below the rubber tip of the leg and a position along the side of the leg. The adapter includes a washer shaped element from which five teeth or prongs depend, similarly to a circular hole saw. The washer with prongs is supported on a bent wire. As with the Janis and Marescalco references, the prongs of the washer-shaped element are susceptible to bending and deformation due to the forces exerted during normal usage, as is the supporting wire. Additionally, the particular geometry of the DMI device prevents the application of force directly along the axis of the leg. Rather, an application of force to the leg results in moments which are applied along the bent wire, enhancing the likelihood of failure of the device due to plastic deformation of the wire, or failure of attachment points of the wire. 
     OBJECTS AND SUMMARY OF THE INVENTION 
     Accordingly, it is a primary object of the invention to provide an assembly that may be coupled to the distal end of a leg whereby the rubber foot of the leg may be exchanged by a friction increasing element, such as a spike or other pointed structure. 
     It is another object of the invention to provide mobility assisting devices which may be more readily utilized in inclement weather conditions, and in snow and ice in particular. 
     An additional object is to provide a traction enhancing device that may be quickly and easily exchanged for a conventional tip by the user. 
     It is a further object of the invention to provide a traction enhancing arrangement for mobility assistance devices which may be economically manufactured. 
     Yet another object is to provide a stable, durable device. 
     In keeping with these and other objects of the invention, there is provided a traction assembly that may be coupled to the distal of the leg of a mobility assisting device such as a cane, crutch, or walker. The distal end of the leg is provided with a threaded rod or “stud” which extends axially from the end thereof. The threaded rod may be welded or formed directly to the end of the leg, or, preferably, threaded directly into the steel tubing of a cane or an insert disposed within the end of the leg. Interchangeable foot or spike/sleeve assemblies are then threaded onto the axially, outwardly extending rod. In this way, when the user encounters inclement weather conditions, he may unscrew the foot assembly from the axially extending threaded rod and, in its place, screw the spike assembly onto the leg. When again moving indoors or when the inclement weather has ceased, the spike assembly may be easily and quickly exchanged out for the foot assembly. 
     The threaded rod is designed to be of a precision length such that when it is completely assembled, the distal end of the rod comes into direct contact with the head of the spike protruding from the end of the threaded sleeve. Accordingly, all of the force is directed to the absolute center or axis of the tubular material of the cane, crutch, or walker. This feature provides the user with better control in the event of a loss of balance and increased “one-to-one” communication with the surface upon which he or she is traveling. 
     Additional objects, advantages and other novel features of the invention will be set forth in part in the description that follows and in part will become apparent to those skilled in the art upon examination of the following or may be learned with the practice of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a longitudinally extending cross-sectional view of the end of a leg of a mobility assisting device constructed in accordance with the teachings of the invention and including a spike assembly; 
     FIG. 2 is a cross-sectional view of a foot assembly for use with the leg assembly illustrated in FIG. 1; and 
     FIG. 3 is an alternate embodiment of an attachment assembly for attaching the spike or foot assemblies of FIGS. 1 and 2 to the end of the leg of a mobility assisting device, the leg being shown in phantom. 
     FIG. 4 is an exploded view of the device of FIG.  1 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Turning now the drawings, there is shown in FIGS. 1 and 4, the end of a typical leg  10  of a mobility assisting device. In the embodiment shown in FIGS. 1 and 4, the leg  10  is constructed of cane steel tubing, although an alternate construction may be provided. 
     In accordance with the invention, the end of the leg  10  is provided with an attachment assembly  12  whereby a distal end portion having enhanced grip on slippery surfaces may be coupled to the cane (as explained below), a crutch, a walker, or the like. The attachment assembly  12  comprises a threaded rod  14  which extends axially outward from the distal end of the leg  10 . In the embodiment illustrated in FIGS. 1 and 4, the leg  10  is configured such that the threaded rod  14  is threaded directly into an axially extending bore  16  in the end of the leg  10 . It will be appreciated by those of skill in the art that this arrangement is appropriate when the wall of the leg  10  is sufficiently thick permit to such direct connection. Alternately, the threaded rod  14  might be coupled to the leg  10  by welding or may be formed integrally with the leg  10  itself. 
     When the leg  10 A includes a relatively thin wall, the attachment assembly  12 A may further comprise an insert  18 , such as is illustrated in FIG. 3, from which the threaded rod  14 A extends. Preferably, the threaded rod  14 A is disposed coincident with the longitudinal axis of the leg  10 A, as with the embodiment illustrated in FIGS. 1 and 4. In this way, the attachment assembly  12 A illustrated in FIG. 3 presents a threaded rod  14 A as is presented in the embodiment illustrated in FIG.  1  and is utilized in the same manner as described with regard to FIGS. 1 and 4. 
     In order to facilitate assembly to the leg  10 A and to enhance durability, the insert  18  preferably includes a small diameter portion  18 A, which may be received within the bore  16 A, and a flange  18 C which is disposed subjacent the lower surface of the leg  10 A when so received within the bore  16 A. Accordingly, during use, the force is applied evenly from the leg  10 A to the flange  10 C. For cosmetic purposes, the portion  18 B of the insert  18  extending from the leg  10 A preferably has the same outer diameter as the outer diameter of the leg  10 A. The insert  18 A may be coupled to the leg  10 A by any appropriate means. For example, a screw or pin (not shown) may be received through openings  20  in the leg  10 A and insert  18  to couple the attachment assembly  12 A to the leg  10 A. 
     Returning now to FIGS. 1 and 4, to enhance traction during usage, the mobility assisting device is further provided with a spike assembly  22  which may be coupled to the axially extending threaded rod  14 . The spike assembly  22  comprises a spike  24  having a relatively pointed distal end  26  and an enlarged proximal end  28  or head. In order to retain the spike in its axially extending relationship shown in FIG. 1, a collar or spike retainer  30  having an axially extending bore  32  receives the spike  24 . It will be appreciated that the enlarged proximal end  28  of the spike  24  is of a greater diameter than the most distal end of the bore  32 , such that the spike  24  is maintained in position within the bore  32 . Those skilled in the art will appreciated that with the spike assembly  22  illustrated, the user may easily replace the spike  24  itself if a less pointed spike or other structure is desired. 
     On order to couple the spike assembly  22  onto the leg  10 , the axially extending bore  32  of the spike retainer  30  is threaded at its proximal end  34 . In use, the user screws the spike retainer  30  containing the spike  24  onto the threaded rod  14 , the threaded rod being received in the threaded bore  34  to secure the spike assembly  22  to the leg  10 . According to an important feature of the invention, the distal end of the threaded rod  14  comes into direct force contact with the enlarged proximal end  28  of the spike  24 . Thus, these components are preferably of precision dimensions. A washer or the like  35  may be provided to assist in maintaining the spike assembly  22  securely to the leg  10  or to provide a certain level of cushioning between the spike  24  and the threaded rod  14 . 
     To assist in maintaining the spike assembly  22  in a secure position on the end of the leg  10  and prevent the assembly  22  from wearing loose as the user travels, a washer  33  is preferably disposed about the threaded rod  14  between the distal end of the leg  10  and the proximal surface of the spike retainer  30 . In the currently preferred embodiment, a steel neoprene lined washer is utilized. A neoprene lined washer is particularly effective for users whose upper body strength is limited and may have difficulty hand tightening the respective components. Other spring type lock washers may be substituted, however, if limited upper body strength is not an issue for the user. 
     Turning now to FIG. 2, according to an important feature of the invention, a foot assembly  36  may be exchanged for the spike assembly  22  of FIG. 1 when the mobility assisting device is used indoors or on finished surfaces. In the preferred embodiment of the foot assembly  36 , a rubber foot  38  is disposed on a rubber foot retainer  40 . As with the spike retainer  30 , the rubber foot retainer  40  is provided with an axially extending threaded bore  42  for receiving the threaded rod  14  to couple the foot assembly  36  to the leg  10 . 
     The spike  26 , spike retainer  30 , rubber foot retainer  40 , insert  18 , and threaded rod  12  are preferably formed of steel or the like, at least the spike  26  preferably being formed of a hardened steel. In order to enhance manipulation of the interchangeable end assemblies, the spike retainer  30  and the foot assembly  36  are preferably knurled along their outer surfaces, as may be seen in FIG.  4 . 
     While the invention has been explained with regard to a threaded rod extending axially from the distal end of the leg  10 , it will be appreciated by those skilled in the art that an alternate attachment means may be provided. For example, the leg  10  may be provided with an internally threaded bore which receives a threaded rod coupled to the foot assembly or spike assembly.