US2736330A - Crutch - Google Patents

Description

I 2,736,330 1956 A. wooD Feb. 28, CRUTCH Filed May 18, 1953 //v A. wooo, 0R JNVENToR.

ArroR/vfn i United States Patent C) CRUTCH Lorin A. Wood, Los Angeles, Calif.

Application May 18, 1953, Serial No. 355,520

7 Claims. (Cl. 13S- 49) This invention relates to crutches used for walking aids by disabled persons and is directed to an eflcient crutch construction that combines adjustability with structural simplicity.

Simplicity is achieved, in large part, by using a single columnar support member in the form of a tubular shaft having an under-arm rest member at its upper end, and having a handgrip member extending laterally from an intermediate portion of the single support shaft. At iirst thought, it would seem that a thoroughly satis factory crutch of this character could consist simply of a straight shaft with a rest member positioned symmetrically on the upper end thereof and with the handgripV member extending perpendicularly from the straight shaft. In actual use, however, such a crutch is found to be awkward, uncomfortable, and noticeably fatiguing. The handgrip is an especially distracting source of discomfort since it does not handle in a natural manner, and changing its height on the shaft or rotating it about the shaft to various trial positions does not eliminate the discomfort.

The invention solves the difficulty of awkwardness and discomfort by positioning the under-arm rest member in an off-center position on the upper end of the shaft with an intermediate portion of the handgrip positioned to be intersected by a straight line extending from the center of the upper rest member to the bottom end of the shaft. Such a straight line may be termed the support axis of the crutch.

The intermediate portion of the handgrip that is on this support axis is the portion on which the heel of the users hand rests to transmit weight to the crutch. Thus, three support lines are placed in a straight line, namely: the upper support point at the center of application of weight to the under-arm rest member; the intermediate support point where weight is transmitted to the handgrip; and the bottom support point where the lower end of the crutch transmits the total weight to the floor or ground. With such alignment of the support points, and especially with the handgrip extending substantially perpendicular to the support axis, there is a desirable naturalness in the manner in which the crutch responds to manual manipulation there being no troublesome tendency for the crutch to twist in response to the weight applied to the handgrip.

In practice, it has been found that the desired result may be attained with the major portion of the shaft substantially straight, with the axis of this major portion of the shaft at an angle of approximately 3 degrees from the support axis and with the handgrip substantially normal to the support axis, i. e., inclined downward about 3% from 'a position perpendicular to the axis of the straight portion of the shaft. With these angular relations, the central or intermediate portion of the shaft is oset from the support axis and, of course, the upper rest member is in offset position relative to .the axis of the intermediate and lower portions of the shaft. The whole shaft may be straight with the upper ICC rest mounted thereon in such manner as to extend to one side thereof or the upper end of the shaft may be bent or curved to hold the upper rest member in the desired offset position.

With reference to adjustability, two adjustments are required, namely, adjustment in overall length and adjustment in the elevation of the handgrip on the shaft. ln the preferred practice of the invention both kinds of adjustment are achieved by means including adjustment screws that are concealed and yet readily accessible. Thus the only tool required to make a change in adjustment is a screw driver.

The various features and advantages of the inventio will be apparent in the following detailed description considered with the accompanying drawings:

In the drawings, which are to be regarded as merely illustrative:

Figure 1 is a side elevation of a selected embodiment of the invention;

Figure 2 is a section taken on the broken line 2-2 of Figure l;

Figure 3 is a section taken along the line 3-3 of Figure l;

Figure 4 is a fragmentary View partly in section and partly in side elevation showing the construction at the juncture between the handgrip and the shaft;

Figure 5 is a sectional view of the bottom end of the crutch; and

Figure 6 is a side elevation of a second embodiment of the invention.

The principal parts of the first form of the invention shown in Figures l and 5 include: a single support shaft 10; a rest member 11 on the upper end of the shaft for positioning under the arm crotch of the user; a lateral handgrip 12 positioned at an intermediate point on the shaft; and the usual rubber member 13 that forms a cushioning tip at the lower end of the crutch for non-slipping contact with a support surface.

The rest member 11 is shaped with an upper arcuate support surface 17 to receive the under-arm weight of the user with the center of the weight or downwardly applied pressure at the point indicated by the arrow 18. The handgrip 12 also bears a portion of the users weight which is applied by the heel of the users hand in the region of the root of the thumb, the center of this application of downward pressure on the handgrip being indicated by the second arrow 19. In accord with the invention, these two centers of pressure application 18 and 19 are on a straight-line support axis 2t? which is indicated by the dotted line in Figure 1 and which extends to the center of the bottom end of the crutch.

Since the pressure center 19 on the handgrip 12 is necessarily spaced away from the juncture of the handgrip with the shaft 10, the shaft 10 in the region of the handgrip is correspondingly oiset from the support axis 20. In this particular embodiment of the invention, the major portion of the shaft 10 extending upward from the lower end of the shaft to a point above the handgrip 12 is substantially straight and the required oifset of the shaft from the pressure point 19 on the handle 12 is achieved by inclining this major straight portion of the shaft away from the support axis 2t) by an angle of approximately 3 degrees. Preferably the bottom face 21 of the rubber member 13 is correspondingly inclined by approximately 3 degrees from the axis 22 of the shaft to make the bottom face substantially perpendicular to the support axis 2l).

The upper rest member 11 may be of any suitable construction and may be mounted on the upper end of the shaft 10 in any suitable manner that offsets the upper pressure point 18 from the axis of the major portion of the shaft. In this first form of the invention, for example, the upper end of the shaft is curved across the support axis Ztl as indicated in Figure 1 for connection to the underside of the rest member 11.

Preferably, the rest member 11 is a one-piece member of wood or a suitable plastic and is formedv with a groove o-n its underside to receive the curved upper end of the shaft 1t). As indicated in Figure l, the rest member 11 may be attached to the shaft 10 by suitable screws 26. it is advantageous to provide threaded tubular inserts (not shown) in the rest member for engagement by the screws. A further feature of the preferred practices of the invention is the formation of the rest member 11 with a central aperture 28 which not only serves to reduce the weight of the crutch and to improve the appearance of the crutch, but also serves as means to permit the crutch to be hung on a hook or nail when not in use.

The mounting of the rest member 11 on a curved end portion of the shaft 1i), in the manner described, has certain structural advantages. The weight imposed on the shaft 16 by the rest member is distributed over a relatively extensive surface o-f the shaft so that concentration of stresses is avoided. It is further apparent that only a minor component of the applied vertically 'l downward pressure is directed across the screws 26 perpendicularly thereof to stress the screws in shear.

The handgrip 12 may be mounted on the intermediate portion of the shaft 1li in any suitable manner, but preferably in a manner permitting adjustment of the elevation of the handgrip. As best shown in Figure 3, the handgrip 12 may comprise a metal tube 3@ and a collar 31 integral therewith for embracing the shaft lit) in a sliding manner. The interior of this member provides a passage longitudinally of the handgrip having three parts, namely: a smooth inner bore 32 to slidingly house a clamping plug 33; an intermediate threaded portion 35 for a screw 36; and an outer smooth bore 37 of a diameter to admit the screw 36. Preferably a handle sleeve 38 of rubber-like material embraces the metal tube 30 to provide a yielding grip for the user.

In the described handgrip construction, the clamping plug 33 is adapted for pressure contact with the periphery of the shaft 10 and for that purpose the inner end of the clamping plug may be of forked configuration, being formed with converging pressure faces du. lt is apparent that the screw 36 may be tightened to force the clamping plug 33 into contact with the shaft 10 with sufficient pressure to immobilize the handgrip 12 on the shaft, and that the screw 36 may be loosened when desired to permit the handgrip to be adjusted upwardly or downwardly on the shaft.

The feature of adjustability in length of the crutch may be provided in various ways in various practices of the invention. As shown in Figure 5, for example, adjustability may be achieved by using a supplemental tube 45 as an interchangeable extension at the lower end of the main shaft tube l0. in the present construction, the suppiemental tube 4S is mounted coaxially on the end of the main tube 10 by means of a tubular core 48 that has a circumferential end flange t9 to abut the supplemental tube 45 and is adapted for insertion through the supplemental tube into the main tube. The inner or upper end of the tubular core 48 is radially expansile for releasable engagement with the main tube 1t) and for this purpose is formed with a plurality of expansion fingers S0 at its inner end. Mounted inside the tubular core 4S is a suitable screw Si. The expansion fingers Si) have convergent inner faces 52 in the path of the screw 51, so that tightening the screw expands the fingers by wedging action into effective pressure engagement with the surrounding wall of the main tube 10. It is contemplated that a series of supplemental tubes 45 progressively varied in length will be available to be mounted interchangeably on the bottom end of 4 the main tube it) for the purpose of changing the effective length of the crutch.

The utility of the crutch and the manner in which it may be adjusted to meet the needs of individual users may be readily understood from the foregoing description. rihe screw S6 inside the handgrip 12 is concealed but nevertheless is conveniently accessible for rotation by an ordinary screw driver, so that the screw may be loosened for adjustment of the height of the grip member without requiring any special tools and without requiring any special skill. The screw 51 at the bottom end of the crutch is also concealedV but `at the same time readily accessible for rotation by a screw driver so that the tubular core 48 may be withdrawn from the lower end of the main tube 16 to permit the replacement of the supplemental tube by a second supplemental tube of different length thereby to vary the effective length of the crutch.

The second embodiment of the invention shown in Figure 6 is largely identical with the first described embodiment of the invention, as indicated by the use of corresponding numerals to designate corresponding parts. ln this particular construction, the tubular shaft 10a is substantially straight throughout its length, beingA .inclined approximately 3 degrees from the support axis 20 as` heretofore described. The rest member 55 on the upper end of the shaft 10a may be of `any suitable construction to place the pressure point 18 or center of weight application in the offset relation with respect to the axisV of shaft 10a to conform to the support axis 20.

ln the illustrated construction, the rest member 55, which is formed with a triangular aperture 56, isprovided with a cylindrical socket 57 to receive the upper end of the tubular shaft 10a. Suitable cross pins or screws 60 in the body of the rest member 55 may extend through corresponding apertures in the tubular shaft 10a for the purpose of effectively interlocking the rest member 55 with the shaft.

ln this embodiment of the invention the hand grip is mounted on the intermediate portion of the shaft 10a in exactly the same manner as is the hand grip mounted in the earlier described embodiment of the invention. In this form of the hand grip the rubber sleeve is molded with a laterally extending protuberanceA 38a which actsk to prevent movement of the hand. longitudinally of the hand grip in a direction away from the tubular shaft forming the body of the crutch. This hand grip formation is of particular importance for patients who do not have full control of their hands and who are not 'able to tightly clasp the hand grip during the use of the crutch.

Although the new preferred embodiments of the present invention have been shown and described herein, it .is to be understood that the invention is not to be limited thereto, for it is susceptible to changes in form and detail within the scope of the appended claims.

l claim:

l. A crutch comprising: a single support shaft, an under-arm rest member mounted on the upper end of the shaft; and a handgrip mounted on said shaft at an intermediate point thereof and extending laterally therefrom, the upper end portion of said shaft being offset to extend from said rest member in a direction Iaway. from a straightline support axis extending from the center of' weight application on said rest member to the bottom end of the shaft, the remaining major portion of said shaft below said offset end portion being substantially straight with said support axis intercepting the intermediate portion of said handgrip where weight is imposed by the users hand.

2. A crutch as set forth in claim l in which said rest member is a one-piece member having a transverse aperture to lighten the crutch and to permit the crutch to be hung up when not in use.

3. A crutch as set forth in claim l in which the upper end of said shaft above the level of the lowermost part of said rest member curves laterally across said support axis and in which said rest member is attached to the upper side of said curved end. l

4. A crutch as set forth in claim 1 in which said center of Weight application on said rest member is offset from the axis of the straight portion of the shaft in the plane of said handgrp.

5. A crutch as set forth in claim 1 in which the major straight portion of the shaft is at an angle of approximately 3 degrees from said support axis.

6. A crutch as set forth in claim 5 in which the axis of said handgrp -is substantially perpendicular to said support axis.

7. A crutch as set forth in claim 6 in which said handgrip is adjustable along the straight portion of the shaft.

References Cited inthe le of this patent UNITED STATES PATENTS Calentine Apr. 14, 1903 Seyferye Dec. 26, 1944 Wheeler Nov. 13, 1945 Brickson Oct. 1, 1946 Neptune Sept. 18, 1951 Henderson et al. June 23, 1953 FOREIGN PATENTS Norway Sept. 16, 1940

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