US3251372A

US3251372A - Friction crutch tip

Info

Publication number: US3251372A
Application number: US352219A
Authority: US
Inventors: Alfred A Smith
Original assignee: Individual
Current assignee: Individual
Priority date: 1964-03-16
Filing date: 1964-03-16
Publication date: 1966-05-17
Anticipated expiration: 1983-05-17

Description

May 17,, 1966 A. A. SMITH FRICTION CRUTCH TIP Filed March 16, 1964 INVENTOR. ALFRED A. 544/771 United States Patent 3,251,372 FRICTION CRUTCH TIP Alfred A. Smith, 8277 Lakershim Blvd North Hollywood, Calif. Filed Mar. 16, 1%4, Ser. No. 352,219 Claims. (Cl. 135-64) This invention relates to a friction crutch tip for use on crutches and canes.

It is the primary object of the invention to provide a new and improved crutch tip which is safer because it provides greater friction between the tip and the ground than the tips that are presently in use.

It is a more particular object of my invention to provide a tip in which the base or ground engaging portion of the tip includes a plurality of separate ground engaging members, each of which has edges which are adapted to take a separate grip upon the ground.

With my improved tip, the edges of a plurality of separate members engage the ground both at the beginning of the crutch movement, when the tip first engages the ground and is subjected to impact and at the end of the crutch movement, before the tip leaves the ground and when it is subject to thrust from the user.

Another object of my invention is to provide a crutch tip which in its preferred embodiment works equally well at any angle and in any direction.

In essence, my invention contemplates a crutch tip hav-' ing a preferably flat ground engaging base which is divided into a plurality of separate or separable sections-or segments, each of which has edges which are adapted to engage the ground. Whenthe tip is flexed, the separation of the segments is increased, thus increasing the frictional engagement of the tip with the ground, the coeflicient of friction of the'tip thus being increased in relationship to the frictional need as indicated by the flexing of the tip. At the same time, means are provided for limiting the separation of the segments to assure their return to their normal positions and to prevent foreign matter from being trapped in the area between the segments.

It is accordingly among the objects of my invention to provide a new and improved crutch tip having all of the advantages and benefits of the structure set forth above and described in greater detail hereinafter in this-specification.

My invention also comprises such other objects, advantages and capabilities as will later more fully appear and which are inherently possessed by my invention.

While I have shown in the accompanying drawings preferred embodiments of my invention, it should be understood that the same are susceptible of modification and change without departing from the spirit of my invention.

Referring to the drawings,

FIG. 1 is a side elevational view, partly broken away and shown in section, of one embodiment of my friction crutch tip;

FIG. 2 is a bottom plan view of the same;

FIG. 3 is a sectional view of a portion of the bottom of the crutch tip in use, showing the flexing of the lands and the independent frictional engagement of their edges with the ground;

FIG. 4 is a bottom plan view of an alternative bottom configuration;

FIG. 5 is a bottom plan view showing an alternative annular ring 24 is also left uncut.

Patented May 17, 1966 "Ice corrugated pattern of land which may be used instead of or in combination with a straight land.

A preferred embodiment which has been selected to illustrate my invention comprises a crutch tip 10, which is preferably molded of a single piece of rubber or other suitable resilient material. The crutch tip 10 has a thick circular base 11 at the bottom, above which is an integrally formed elongated neck 12. Between the neck 12 and base 11, the crutch tip 10 is provided with an annular groove 13, which defines the horizontal axis of bending movement of the neck 12 with respect to the base 11.

The inside of the crutch tip 10 is provided ith an elongated substantially cylindrical hollow crutch shaft receiving passage 14, the upper Walls of which are provided with alternating lands and grooves, which provide a secure grip around the bottom portion of the cylindrical crutch shaft. The passage 14 has a flat circular bottom, upon which may be mounted a circular metal disc 18, which acts to reduce the frictional wear of the end of the crutch shaft on the bottom of the passage 14.

The bottom of the base 11 is preferably flat. It is provided with a plurality of narrow, deep, concentric grooves 20, which extend a substantial distance upwardly into the base 11. The grooves 20 divide the bottom of the base 11 into a plurality of concentric lands 21. A plurality of radially directed ties 22 extend across the grooves 20, connecting the adjacent lands 21 and dividing each of the lands 21 into a plurality of segments. The lower edges of the ties 22 are disposed slightly upwardly from the lower edges of the lands 21.

A circular plug 23 is left uncut at the center of the 'bottom19, to act as a limit and stop for the inward flexing movement of the segments of the lands 21. An outer The outer ring 24 contains the lands 21 and limits the outward flexing movement of their segments.

A crutch tip of the type described may be molded as a single piece of rubber, with all of the lands 21 and ties 22 being integral, as shown in FIGS. 1-4 of the drawings.

It should be noted that, regardless of the method used, the lower portions of the lands must remain separate and must not be cemented or vulcanized to each other or to the base. The bottom edges must be left free to flex and provide the desired increased frictional engagement with the ground when the tip is flexed. I

In use, my crutch tip functions in a manner completely ditferent from any crutch tip now in use. Referring to FIG. 3 of the drawings, thetip 10 is flexed as it first engages the ground, flexing the base 11 to separate the lands 21 and bring the inner edge of each of the lands 21 into engagement with the ground. The result is that the edge of each of the lands 21 forms an independent frictional engagement with the ground and the resistance of the tip to slipping is the summation of these separate frictional engagements.

When the crutch reaches a vertical position, the bottom of the base is horizontal and the tip 10 then begins to flex in the opposite direction. This flexing acts to separate the lands 21 on the opposite side of the tip, so that their edges engage the ground and resist slippage which might be caused by the thrust against the tip 10 by the user during the latter part of the crutch movement.

. The total amount of friction generated by the plurality of edges of the separate lands engaging the ground is substantially greater than that of a conventional clutch tip.

It should also be noted that the stabilizing ties 22 divide each of the lands 21 into a plurality of short arcuate segments, each of which can move only to a limited degree. This prevents extreme separation of the lands 21, with consequent enlargement of the grooves 20. This is desirable because it assures the prompt return of the lands to their normal positions and because it prevents the grooves from becoming so enlarged that foreign matter such as pebbles, bits of glass, etc., are picked up from the ground and entrapped within the grooves. Such entrapped particles can damage the tip and can also damage floors, carpets, etc.

A concentric circular pattern of the type shown in FIG. 2 of the drawings is believed to be more advantageous because it provides a uniform action regardless of the direction of movement of the crutch tip. It is possible, however, to use other patterns or configurations such as square, diamond, cross-hatch, or any other regular pattern. FIG. 4, for example, shows a concentric square pattern of grooves 32 and lands 33. The lands and grooves may also be corrugated as well as straight, as shown by the corrugated land 34 in FIG. 5 of the drawings. The essential feature is that the bottom of the base must be divided or separated into a plurality of segments, each of which has an edge or portion thereof which provides a separate frictional engagement with the ground when the tip is flexed.

It will be noted that my friction crutch tip does not depend upon suction for any of its ground gripping ability. Such suction tends to be effective mainly at the midportion of the crutch action cycle, when it is actually least needed. The suction is also destroyed as soon as the edge of the crutch tip is worn sufficiently to permit air to enter the suction area.

As shown in FIG. 3 of the drawings, each of the lands 21 has a pair of straight sides defined by the adjacent grooves 20 and a flat bottom, which forms a part of the flat ground engaging bottom portion of the base 11. Each of the lands 21 accordingly has a pair of substantially right angular edges which, upon pivotal flexing movement of the crutch tip 10, flexes into simultaneous but independent engagement with the ground. The frictional resistance of the bottom of the base 11 to slippage comprises the summation of the simultaneous frictional engagements of the edges of the lands 21 with the ground.

I claim:

1. In a friction crutch tip, a base, the ground engaging bottom surface of said being substantially fiat and having a plurality of narrow concentric circular grooves extending a substantial distance vertically upwardly into said base from the bottom thereof, said grooves dividing said base into a plurality of separate concentric circular lands molded integrally with said base and separated from each other by said grooves, each of said lands being substantially Wider than said grooves, a plurality of ties molded integrally with said base, said ties extending across said grooves and joining said lands, each of said ties being substantially equal in width to the width of said lands, said ties extending from the top of said grooves to a point spaced slightly upwardly from the bottom of said grooves, said ties dividing each of said lands into a plurality of arcuate segments, said ties controlling the flexing movement of said segments and preventing excessive enlargement of said grooves, a circular center plug disposed adjacent the center of the bottom of said base, and an annular outer ring extending around the periphery of the bottom of said base, said center plug and outer ring limiting the inward and outward flexing movements of 7 said lands, each of said lands having straight sides and a flat bottom defining a pair of substantially right angular edges, the corresponding edges of a plurality of said lands being adapted to engage the ground independently but simultaneously when said base is flexed upon the pivotal movement of said crutch tip, the frictional resistance of the bottom of said base to slippage comprising the summation of the simultaneous frictional engagements of the edges of said lands with the ground.

2. In a friction crutch tip, a base, the ground engaging bottom surface of said base being substantially flat and having a plurality of narrow concentric circular grooves extending a substantial distance vertically upwardly into said base from the bottom thereof, said grooves dividing said base into a plurality of separate concentric circular lands molded integrally with said base and separated from each. other by said grooves, each of said lands being substantially wider than said grooves, a plurality of ties molded integrally with said base, said ties extending across said grooves and joining said lands, said ties dividing each of said lands into a plurality of arcuate segments, said ties controlling the flexing movement of said segments and preventing excessive enlargement of said grooves, and an annular outer ring extending around the periphery of the bottom of said base, said outer ring limiting the outward flexing movement of said lands, each of said lands having straight sides and a flat bottom defining apair of substantially right angular edges, the corresponding edges of a plurality of said lands being adapted to engage the ground independently but simultaneously when said base is flexed upon the pivotal movement of said crutch tip, the frictional resistance of the bottom of said base to slippage comprising the summation of the simultaneous frictional engagement of the edges of said lands with the ground.

3. In a friction crutch tip, a base, the ground engaging bottom surface of said base being substantially flat and having a plurality of narrow concentric circular grooves extending a substantial distance vertically upwardly into said base from the bottom thereof, said grooves dividing said base into a plurality of separate concentric circular lands separated from each other by said grooves, each of said lands being substantially wider than said grooves, a plurality of ties extending across said grooves and joining said lands, said ties dividing said lands into a plurality of arcuate segments, said ties controlling the flexing movement of said segments and preventing excessive enlargement of said grooves, each of said lands having straight sides and a flat bottom defining a pair of substantially right angular edges, the corresponding edges of a plurality of said lands being adapted to engage the ground independently but simultaneously when said base is flexed upon the pivotal movement of said crutch tip, the frictional resistance of the bottom of said base to slippage comprising the summation of the simultaneous frictional engagements of the edges of said lands with the ground.

4. In a friction crutch tip, a base, the ground engaging bottom surface of said base being substantially flat and having a plurality of concentric narrow grooves extending a substantial distance vertically upwardly into said base from the bottom thereof, said grooves dividing said base into a plurality of separate concentric lands separated from each other by said grooves, a plurality of ties extending across said grooves and joining said lands, said ties dividing said lands into a plurality of arcuate segments, said ties controlling the flexing movement of said segments and preventing excessive enlargement of said grooves, each of said lands having a pair of edges, the corresponding edges of a plurality of said lands being adapted to engage the ground independently but simultaneously when said base is flexed upon the pivotal movement of said crutch tip, the frictional resistance of the bottom of said base to slippage comprising the summation of the simultaneous frictional engagements of the edges of said lands with the ground.

5. In a friction crutch tip, a base, the ground engaging bottom surface of said base having a plurality of narrow grooves extending a substantial distance vertically upwardly into said base from the bottom thereof, said grooves dividing said base into a plurality of lands separated from each other by said grooves, each of said lands having a pair of edges, the corresponding edges of a plurality of said lands being adapted to engage the ground independently but simultaneously when said base is flexed upon the pivotal movement of said crutch tip, the frictional resistance of the bottom of said base to slippage comprising the summation of the simultaneous frictional engagements of the edges of said lands with the ground, and a plurality of ties extending across said grooves and joining said lands, said ties dividing said lands into a plurality of segments, said ties controlling the flexing movement ofsaid segments and preventing excessive enlargement of said grooves.

References Cited by the Examiner UNITED STATES PATENTS 879,471 2/1908 Kabureck 135-64 2,661,041 12/1953 Walsh 152 209 3,040,757 6/1962 Smith 135--64 FOREIGN PATENTS 963,349 12/1949 France.

10 HARRISON R. MOSELEY, Primary Examiner.

L. J. SANTISI, Assistant Examiner.

Claims

4. IN A FRICTION CRUTCH TIP, A BASE, THE GROUND ENGAGING BOTTOM SURFACE OF SAID BASE BEING SUBSTANTIALLY FLAT AND HAVING A PLURALITY OF CONCENTRIC NARROW GROOVES EXTENDING A SUBSTANTIALLY DISTANCE VERTICALLY UPWARDLY INTO SAID BASE FROM THE BOTTOM THEREOF, SAID GROOVES DIVIDING SAID BASE INTO A PLURALITY OF SEPARATE CONCENTRIC LANDS SEPARATED FROM EACH OTHER BY SAID GROOVES, A PLURALITY OF TIES EXTENDING ACROSS SAID GROOVES AND JOINING SAID LANDS, SAID TIES DIVIDING SAID LANDS INTO A PLURALITY OF ARCUATE SEGMENTS, SAID TIES CONTROLLING THE FLEXING MOVEMENT OF SAID SEGMENTS, AND PREVENTING EXCESSIVE ENLARGEMENT OF SAID GROOVES, EACH OF SAID LANDS HAVING A PAIR OF EDGES, THE CORRESPONDING EDGES OF A PLURALITY OF SAID LANDS BEING ADAPTED TO ENGAGE THE GROUND UNDEPENDENTLY BUT SIMULTANEOUSLY WHEN SAID BASE IS FLEXED UPON THE PIVOTAL MOVEMENT OF SAID CRUTCH TIP, THEFRICTIONAL RESISTANCE OF THE BOTTOM OF SAID BASE TO SLIPPAGE COMPRISING THE SUMMATION OF THE SIMULTANEOUS FRICTIONAL ENGAGEMENTS OF THE EDGES OF SAID LANDS WITH THE GROUND.