US3537463A

US3537463A - Crutch

Info

Publication number: US3537463A
Application number: US783267A
Authority: US
Inventors: Alfred A Smith; Van Nuys; Lorin A Wood
Original assignee: Guardian Products Co Inc
Current assignee: Guardian Products Inc
Priority date: 1968-12-12
Filing date: 1968-12-12
Publication date: 1970-11-03
Anticipated expiration: 1987-11-03

Description

United States Patent Alfred A. Smith Van Nuys;

Lorin A. Wood, Lakewood, California 783,267

Dec. 12, 1968 Nov. 3, 1970 Guardian Products Company,lnc. North Hollywood, California a corporation of California lnventors Appl. No. Filed Patented Assignee CRUTCH 15 Claims, 15 Drawing Figs.

U.S. Cl 135/50 lnt.Cl A6lh 3/02 Field of Search l35l49-52 [56] References Cited UNITED STATES PATENTS 2,241,481 5/1941 Schroeder 135/50 2,408,604 10/1946 Brickson l35/50X 2,568,654 9/1951 Neptune... 135/50 2,736,330 2/1956 Wood 135/52X FOREIGN PATENTS 722,428 11/1965 Canada 135/50 Primary Examiner-J. Karl Bell Attorney-Smyth, Roston and Pavitt ABSTRACT: The major portion of the length of a crutch comprises two longitudinal wood bars with a uniform space therebetween and the lower end of the crutch is a single shaft that extends upward through the uniform space for adjustable anchorage to the two wood bars to reinforce a substantial longitudinal portion of the two bars.

Patented Nov. 3, 1970 3,537,463

Sheet 1 of2 CRUTCII BACKGROUND OF THE INVENTION In general there are three different types of crutches. The most expensive crutch is made of tubular chrome alloy steel. The second type ofcrutch which is disclosed in the Wood US. Pat. No. 2,736,330 is made of aluminum tubing and costs a little more than one fourth as much as the chrome alloy steel crutch. The third type of crutch is the conventional wood members ofa conventional crutch converge onto a lower shaft that forms the lower end of the crutch. Since the lower shaft must be adjustable relative to the two spaced bars for adjustment in length of the crutch, the lower shaft extends upwardly centrally of the relatively wide space between the two wood bars. The upper end of the lower shaft member that lies in the relatively wide space between the two wood bars has no useful function and merely adds weight to the crutchfor the sake of longitudinal adjustment of the crunch. The extension of the lower shaft into the relatively wide space between the two wood bars, moreover, results in a design that is far from neat and in fact is somewhat unsightly.

The present invention fills the need for a crutch that is in approximately the same price range as the described conventional wood crutch but is lighter in weight and at the same time is both more efficient structurally and of more pleasing design.

SUMMARY OF THE INVENTION Two embodiments ofa crutch are disclosed herein. In both embodiments, the crutch has an upper portion with an underarm rest member mounted on the upper end thereof, an intermediate portion with a hand grip extending rearwardly therefrom and a lower end portion, the upper portion being curved to bow the crutch forwardly from a straight line support axis that extends from the underarm rest member to the lower end of the crutch. The intermediate and lower end portion of the crutch are substantially straight with said support axis intercepting the hand grip where the weight is imposed by the user's hand.

In both embodiments the intermediate portion of the shaft structure comprises two longitudinal support members or bars that are uniformly spaced apart by substantially less than the spacing of the two longitudinal bars ofa conventional crutch and the lower end portion of the crutch is formed by a single shaft member that extends upwardly into the uniform space between the two longitudinal bars. This lower shaft is in close contact with both of the longitudinal bars for reinforcement thereof throughout the region where the lower shaft is coextensive with the two longitudinal bars and the lower shaft is longitudinally adjustable between the two spaced bars for adjustment in the length of the crutch. Thus all of the upper portion of the-lower shaft that extends between the two spaced bars has utility in adding structural strength to the crutch and the fact that the two bars are spaced apart by only the thickness of the lower shaft results in a pleasingly compact and streamlined design.

In the first embodiment of the invention the upper end of the crutch is formed by a single shaft of curved configuration that extends downwardly between the two spaced bars of the intermediate portion ofthe crutch so that the upper shaft reinforces the two spaced bars in the same manner as the lower shaft. In this first embodiment the hand grip is fixedly mounted on the two spaced bars of the intermediate portion of the crutch but the distance of the hand grip from the lower LII end of the crutch may be varied by varying the adjustment of the lower shaft relative to the two spaced bars and the distance between the underarm rest member and the hand grip may be varied by adjusting the upper shaft relative to the two bars.

In the second embodiment of the invention, the two spaced bars that form the intermediate portion of the crutch are extended upward to form the upper portion of the shaft that is connected to the underarm rest member. The upper portion of the crutch is not longitudinally adjustable relative to the intermediate portion but the hand grip is adjustable longitudinally of the two bars. Thus the distance from the underarm rest member to the hand grip may be varied by adjusting the position of the hand grip longitudinally of the two bars and the distance from the hand grip to the lower end of the crutch as well as the overall length of the crutch may be varied by adjusting the lower shaft longitudinally relative to the two bars.

A feature of the second embodiment of the invention is the provision of a spacer between the two bars at the upper end portion of the crutch, the spacer being bonded to the two bars to form therewith a beam member having a relatively large moment of inertia.

As will be explained, additional features of the invention relate to the manner in which the underarm rest members are mounted on the two embodiments of the crutch. Another feature is the manner in which the hand grip is mounted for adjustment longitudinally of the intermediate portion of the second embodiment ofthe crutch.

The various features and advantages of the invention may be understood from the following detailed description and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings, which are to be regarded as merely illustrative:

FIG. 1 is a side elevation of the first embodiment of the invention;

FIG. 2 is a cross section taken as indicated by the line 2-2 of FIG. 1 showing how the upper shaft is connected to the two spaced longitudinal bars;

FIG. 3 is a section taken as indicated by the line 3-3 of FIG. 1 showing how the hand grip is mounted on the crutch;

FIG. 3a is a side elevational view of the hand grip as seen along the line 311-311 of FIG. 3;

FIG. 4 is an enlarged sectional view of the upper end of the crutch showing how the underarm rest member is mounted on the curved end of the upper shaft;

FIG. 4a is a cross section of a sheet metal washer employed in the construction shown in FIG. 4;

FIG. 5 is a transverse section taken as indicated by the line 5-5 of FIG. 1 showing how the lower shaft is adjustably connected to the two wood bars of the intermediate portion of the crutch;

FIG. 6 is a transverse sectional view similar to FIG. 5 showing a modification of the structure of the first embodiment of the crutch;

FIG. 7 is a fragmentary sectional view showing a different manner of mounting the underarm rest on the crutch;

FIG. 8 is a side elevational view of the second embodiment of the crutch;

FIG. 9 is an enlarged fragmentary sectional view of the upper end of the crutch of the second embodiment of the crutch showing how the underarm rest is mounted;

FIG. 11 is a transverse section along the line 11-11 of FIG.

FIG. 10 is a transverse section along the line 10-10 of FIG. I

DESCRIPTION OF THE EMBODlMENTS OF TI'IIE. INVENTION The first embodiment of the invention shown in FIGS. 1 to 6 is a crutch having an intermediate portion formed by two uniformly spaced longitudinal support members 10 which preferably are in the form of five plywood bars or strips, the upper and lower ends of which may be rounded as indicated. A hand grip in the form of a handle 11 is mounted on the intermediate portion of the crutch by an axial bolt 12 which extends through a spacer block 13 and which is permanently secured by a nut 14. Preferably the outer sides of the two wood strips 10 are reinforced by metal plates 15 in the region of the hand grip II, the plates being interconnected by long rivets I6. As shown in FIGS. 3 and 4, the body of the hand grip ll may be formed with parallel lips 17 on its opposite sides to straddle the rearmost wood strip 10 to prevent rotation of the hand grip body on the bolt 12.

The lower end portion of the crutch is formed by a single shaft 18 which is equipped with the usual rubber tip 20 and this shaft extends upward into the uniform space between the two wood strips l0 and is adjustably secured to the two wood strips to permit longitudinal adjustment relative to the two strips. The lower shaft 18 may be made of wood and in the construction shown has a series of vertically spaced cross bores 22 to receive a pair of spaced bolts 24. The bolts 24 extend through corresponding bores in the two wood strips 10 and are equipped with thumb nuts 25. It is apparent that the bolts 24 may be temporarily removed to permit longitudinal adjustment of the lower shaft I8 thereby to vary both the overall length of the crutch and the distance between the hand grip l1 and the bottom end of the crutch.

The upper end portion of the crutch is formed by a single upper shaft 26, the lower portion of which is adjustably connected to the two wood strips 10 in the same manner as the lower shaft 18. As shown in cross section in FIG. 2 the inner surfaces of the two wood strips 10 may be provided with shallow longitudinal recesses 27 shaped to conform to the circular cross section of the metal tube. The upper shaft 26 has a series of vertically spaced cross bores 28 for cooperation with bolts 30 that are equipped with forward wing nuts 32, the two bolts extending through corresponding bores in the two wood strips 10. The usual underarm rest member 33 which is embraced by a hollow rubber cushion 34 is mounted on the upper end of the upper shaft 26.

It is apparent that longitudinal adjustment of the upper shaft 26 relative to the two wood strips 10 changes the overall length of the crutch and at the same time changes the distance between the underarm rest member 33 and the hand grip 12. It is also apparent that the upper portion of the lower shaft 18 and the lower portion of the upper portion 26 constitute structural parts of the intermediate longitudinal portion of the crutch to reinforce the two wood strips 10.

The upper shaft 26 is curved forwardly as shown in FIG. I to give the crutch a forwardly bowed configuration so that what i may be termed the support axis 35 of the crutch if offset rearwardly from the major portion of the crutch. It is to be noted that the support axis 35 substantially bisects the underarm rest member 33 and also intersects the hand grip 11 with the lower end of the support axis converging onto the axis of the lower shaft 18.

In this first embodiment of the invention the upper curved shaft 26 is a metal tube, for example an aluminum metal tube. The underarm rest member 34 may be mounted on the upper end of the tube 26 in any suitable mannerf In the construction shown in FIGS. 1 and 5, the upper end of the metal tube 26 abutsthe underside of the underarm rest member 33 and is cut away to conform with the cross-sectional configuration of the underarm rest member. The curved upper end of the tube 26 is at an acute angle to the underarm rest member 33 and is connected thereto by two

wood screws

36 and 38 which extend through corresponding bores in the wall of the tube and which are screwed into the wood body of the underarm rest member.

A feature of the invention is the employment of a pair of sheet metal washers between the under surface of the tube 26 and the heads of the wood screws 36 and 38. The initial configuration of the two washers is shown in cross section in F I6. 50 where it may be seen that each washer has a toroidal convex surface 42 on its outer side and a toroidal concave surface 44 on its inner side. Thus the washer is of annular convex configuration on its outer side and of annular concave configuration on its inner side. v 7

When the two

screws

36 and 38 are tightened as shown in FIG. 5, the two washers 40 are thereby deformed to conform snugly with the undersurface of the metal tube 26. Thus it is not necessary to provide washers of special shape to conform to the cross-sectional configuration of the curved portion of the metal tube 26 and it is not necessary to deform the metal tube for the purpose of providing seats for the washers.

FIG. 6, which is a sectional view corresponding to FIG. 2, shows how the two wood strips 10 may be replaced by two longitudinal metal tubular members 45 of generally rectangular configuration. As shown in FIG. 6, here again the inner surfaces of the longitudinal members 45 are provided with shallow longitudinal recesses 46 that conform to the circular cross section of the metal tube 26.

FIG. 7 shows another manner of mounting an underarm rest member 330 on the curved upper end of a metal tube 260. The underarm rest member 330 is provided with an inclined bore 48 to serve as a socket for the upper end of the metal tube 260 and the upper end of the tube is bonded to the underarm rest member by epoxy 50 that lines the socket.

In the second embodiment of the invention shown in FIG. 8, the upper end portion as well as the intermediate longitudinal portion of the crutch is formed by two uniformly spaced plywood strips 52. The upper ends of the two wood strips 52 are curved and as best shown in FIGv 9 extend into corresponding epoxy-lined sockets 54 on the underside of underarm rest member 55. For strength and rigidity, a spacer block 56 of substantially the same width as the two plywood strips is inserted between the two strips along the curved portion of the crutch and is adhesively bonded to the two strips, for example by epoxy adhesive to form therewith a unitary beam and thus increase the moment of inertia. In the modification shown in FIGS. 12 and 13, the spacer between the curved portions of the two plywood strips 52 is in the form of a thin plate 58 to reduce weight, the thin plate being adhesively bonded to the two plywood strips by epoxy 60. The thin plate 58 which may be made of a suitable plastic cooperates with the two plywood strips 52 to form a cross-sectional configura-' tion of an l-beam which has exceptional strength and rigidity for a given amount of material.

FIG. 8 shows how a hand grip may be mounted on the intermediate portion of the crutch in a manner that permits adjustment of the hand grip longitudinally of the crutch. For this purpose the two plywood strips 52 are reinforced by an interposed spacer block 64 and the two plywood strips and the spacer block are provided with s series of vertically spaced transverse bores 65 to receive an axial bolt 66 on which the handle is mounted. The axial bolt is provided with a suitable wing nut 68 which may be easily removed whenever a change in the elevation of the handgrip is desired.

The outer faces of the two plywood strips 52 may be reinforced by corresponding

metal plates

70 and 72 in the region of adjustment of the hand grip 62, the two plates being secured by a pair of long rivets 74. As shown in cross section in FIG. II, the inner end face of the handle 62 is formed with a pair of parallel vertical grooves 75 on opposite sides of the bolt 66 and the metal plate 70 is formed with a corresponding pair of ribs 76 that extend along the length of the plate and en 62 in the form of a handle I plywood strips 52, the inner longitudinal surfaces of the plywood strips being provided with shallow recesses as heretofore described to conform to the cross-sectional configuration of the metal tube.

The metal tube 80 is adjustable longitudinally of the two plywood strips 52 and for thispurpose has a series of vertically spaced transverse bores 82 for cooperation with a pair of bolts 84 that are provided with wing nuts 85. The two bolts 84 extend through corresponding bores in the plywood strips 52 and may be temporarily removed for longitudinal adjustment of the metal tube 80. It is apparent that adjustment of the hand grip 62 longitudinally of the crutch varies the distance between the hand grip and the underarm rest member 55 and that longitudinal adjustment of the tube 80 both varies the length of the crutch and varies the distance of the hand grip 11 from the lower end of the crutch. p 7

Our description in specific detail of the selected embodiments of the invention will suggest various changes, substitutions and other departures from our disclosure.

We claim:

l. A crutch having in combination:

a support shaft structure having an upper portion, an intermediate portion and a lower portion;

an underarm rest member mounted on the upper end of said upper portion of the shaft structure;

a hand grip mounted on said intermediate portion of the shaft structure and extending rearward therefrom; at least a portion of said upper portion of the support shaft structure being curved to bow forwardly from a straight line support axis extending from the center of said rest member to the bottom end of the support shaft structure;

said intermediate and lower portions of the shaft structure being substantially straight with said support axis intercepting the intermediate portion of said hand grip where weight is imposed by the users hand;

said intermediate portion of the support shaft structure comprising two longitudinal support members which are separate from each other throughout the intermediate portion with one uniformly spaced rearwardly of the other and forming therewith a longitudinal space of substantially uniform cross-sectional configuration;

said lower portion of the support shaft structure comprising a lower longitudinal support member of a cross-sectional configuration conforming with the cross-sectional configuration of said longitudinal space and spanning the longitudinal space, said lower longitudinal support member extending upward into said longitudinal space in close contact with both of said two longitudinal support members to reinforce the two longitudinal support members throughout the region where the lower longitudinal support member is coextensive with the two longitudinal support members, the coextensive part of the lower support member being a structural part of said intermediate portion ofthe support shaft structure; and

means interconnecting said two longitudinalsupport members through said lower longitudinal support member in said region thereby uniting the two longitudinal support members as well as connecting the two longitudinal support members to the lower support member, said connecting means being releasable to permit longitudinal adjustment of said lower longitudinal support member relative to said two longitudinal support members for the purpose of varying the length of the crutch.

2. A crutch as set forth in claim 1 in which two longitudinal support members are made of wood to make the crutch relatively light in weight.

3. A crutch as set forth in claim 2 in which said two longitudinal support members are thin-walled hollow metal members.

4. A crutch having in combination:

a support shaft structure having an upper portion, an inter mediate portion and a lower portion;

a hand grip mounted on said intermediate portion of the I shaft structure and extending rearward therefrom;

at least a portion of said upper portion of the support shaft structure being curved to bow forwardly from a straight line support axis extending from the center of said rest member to the bottom end of the support shaft structure;

said intermediate and lower portions of the shaft structure being substantially straight with said support axis intercepting the intermediate portion of said hand 'grip where weightis imposed by the user's hand;

said intermediate portion of the support shaft structure including two longitudinal support members with one spaced rearwardly of the otherand forming therewith a longitudinal space of substantially uniform cross-sectional configuration;

said lower portion of the support shaft structure comprising a lower longitudinal support member of a cross-sectional configuration to conform with the cross-sectional configuration of said longitudinal space, said lower longitudinal support member extendinglupward into said longitudinal space in close contact with both of said two longitudinalsupport members to reinforce the two longitudinal support members throughout the region where the lower longitudinal support member is coextensive with the two longitudinal support members, the coextensive part of the lower support member being a structural part of said intermediate portion of the support shaft structure;

spacer means in said longitudinal space above said region;

fastener means extending through said hand grip, through said two longitudinal support members and through said spacer means to attach the hand grip to the crutch.

5. A crutch as set forth in claim 4 in which said fastener means is adjustable to adjust the distance of the hand grip from the bottom end of the support shaft structure.

6. A crutch as set forth in claim 4'in which said hand grip has an end face confronting the rear surface'of the rearward longitudinal support member of the two longitudinal support members: I

in which said fastening means extends through the axial region of the hand grip;

in which said confronting face of the hand grip has at least one recess;

and in which the rearward of the two longitudinal support members has a projection cooperating with sai d recess to prevent rotation of the hand grip about its axis. ,7 I

7. A crutch as set forth in claim 6 in which said confronting face of the hand grip has a recess in the form of an upright groove:

in which said projection on the rearward of the two longitudinal support members is a longitudinal rib to cooperate with said groove to prevent rotation of the'hand grip on its axis; and

in which said intermediate portion of the support shaft structure has a plurality of vertically spaced bores to receive said fastener means to permit adjustment in the portion of the hand grip longitudinally of said intermediate portion.

8. A crutch as set forth in claim 6 in which said confronting face of the hand grip is formed with parallel upright grooves on opposite sides of its axis; and in which the rearwardof the two longitudinal support members has a pair of ribs to cooperate with the pair of grooves to prevent rotation of the hand grip.

9. A crutch having in combination:

a hand grip mounted on said intermediate portion of the shaft structure and extending rearward therefrom;

at least a portion of said upper portion of the support shaft structure being curved to bow forwardly from a'straight line support axis extending from the center of said rest member to the bottom end of the support shaft structure;

said intermediate portion of the support shaft structure including two longitudinal support members with one spaced rearwardly of the other and forming therewith a longitudinal space of substantially uniform cross-sectional configuration;

said lower portion of the support shaft structure comprising a lower longitudinal support member of a cross-sectional configuration to conform with the cross-sectional configuration of said longitudinal space, said lower longitudinal support member extending upward into said longitudinal space in close contact with both of said two longitudinal support members to reinforce the two longitudinal support members throughout the region where the lower longitudinal support member is coextensive with the two longitudinal support members, the coextensive part of the lower support member being a structural part of said intermediate portion of the support shaft structure;

- means to interconnect said two longitudinal support members and said lower longitudinal support member in said region, said connecting means being releasable to permit longitudinal adjustment of said lower longitudinal support member relative to said two longitudinal support members for the purpose of varying the length of the crutch;

said upper portion of the support shaft structure comprising an upper longitudinal support member of a cross-sectional configuration corresponding to the cross-sectional configuration ofsaid longitudinal space; said upper longitudinal support member extending downward into said longitudinal space in close contact with both of said two longitudinal support members to reinforce the two longitudinal support members throughout the region where the upper single longitudinal support member is coextensive with the two longitudinal support members, the coextensive part of the upper longitudinal support member being a structural part of said intermediate portion of the support shaft structure;

means interconnecting said upper longitudinal support member and said two longitudinal support members in said upper region; and

said intermediate and lower portions of the shaft structure being substantially straight with said support axis intercepting the intermediate portion of said hand grip where weight is imposed by the users hand.

10. A crutch as set forth in claim 9 in which the upper portion of said upper longitudinal support member is curved adjacent said underarm rest member for forward bowing of the support shaft structure:

in which the upper end of said upper longitudinal support member is shaped to conform with the configuration of the underside of said underarm rest member;

in which headed screws extend through the curved portion of said upper longitudinal support member into the underarm rest member to connect the upper longitudinal support member to the arm rest member;

in which a sheet metal washer embraces each of said screws in abutment with the head of the screw and in abutment with the curved surface of the upper longitudinal support member;

each of said sheet metal washers being offset to a configuration that is annularly concave on the inner side of the washer and annularly convex on the outer side of the washer; and

each of said washers being deformed with its inner side conforming to the curved surface of the upper longitudinal support member.

11. A crutch as set forth in claim 9 in which said upper longitudinal support member is a metal tube and the confronting surfaces of said two longitudinal support members are shaped to conform to the cross-sectional configuration of the metal tube.

12. A crutch having in combination:

an underarm rest member mounted on the upper end of said at least a portion of said upper portion of the support shaft structure being curved to bow the support shaft structure from a straight line support axis that extends from the central portion of said rest member to the bottom end of the support shaft structure;

said upper portion and said intermediate portion of the support shaft structure comprising two longitudinal support members which are separate from each other throughout the intermediate portion, one spaced uniformly rearwardly of the other and forming therewith a longitudinal space of substantially uniform cross-sectional configuration; 1

a lower longitudinal support member of a cross-sectional configuration conforming with the cross-sectional configuration of said longitudinal space, said lower longitudinal support member extending upward into said longitudinal space in close contact with both of said two longitudinal support members to reinforce the two longitudinal support members throughout the region where the lower longitudinal support member is coextensive with the two longitudinal support members, the coextensive part of the lower support member being a structural part of said intermediate portion of the support shaft structure; and

means interconnecting said two longitudinal support members through said lower longitudinal support member in said region thereby uniting the two longitudinal support members as well as connecting the two longitudinal support members to the lower longitudinal support member, said connecting means being releasable to permit longitudinal adjustment of said lower longitudinal support member relative to said two longitudinal support members for the purpose of varying the length of the crutch.

13. A crutch having in combination:

an underarm rest member mounted on the upper end of said upper portion of the shaft structure a'hand grip mounted on said intermediate portion of the shaft structure and extending rearward therefrom;

at least a portion of said upper portion of the support shaft structure being curved to bow the support shaft structure from a straight line support axis that extends from the central portion of said rest member to the bottom end of the support shaft structure;

spacer means in the curved portion of said upper portion of the support shaft structure, said spacer means spanning said longitudinal space and being bonded to both of said longitudinal support members to form therewith a beam;

said upper portion and said intermediate portion of the support shaft structure comprising two longitudinal support members, one spaced rearwardly of the other and forming therewith a longitudinal space;

means to interconnect said two longitudinal support members and said lower longitudinal support member in said region, said connecting means being releasable to permit longitudinal adjustment of said lower longitudinal support member relative to said two longitudinal support members for the purpose of varying the length of the crutch.

14. A crutch as set forth in claim 13 in which said spacer means is a web member substantially thinner than said longitudinal space.

15. A crutch having in combination:

said two longitudinal support members being curved at their upper ends;

said underarm rest having two inclined sockets on its underside receiving the upper ends of the two longitudinal support members, said upper ends being adhesively bonded to the underarm rest member inside said sockets,

said intermediate and lower portions of the shaft structure being substantially straight with said support axis intercepting the intermediate portion of said hand grip where weight is imposed by the user's hand;

a lower longitudinal support member of a cross-sectional configuration conforming with the cross-sectional configuration of said longitudinal space, said lower longitudinal support member extending upward into said longitudinal space in close contact with both of said two longitudinalsupport members to reinforce and two longitudinal support members throughout the region where the lower longitudinal support member is coextensive with the two longitudinal support members, the coextensive part of the lower support member being a structural part of said intermediate portion of the support shaft structure; and