US3897857A

US3897857A - Wheelchair hub brake

Info

Publication number: US3897857A
Application number: US475526A
Authority: US
Inventors: Keith S Rodaway
Original assignee: Everest and Jennings Inc
Current assignee: Everest and Jennings Inc
Priority date: 1974-06-03
Filing date: 1974-06-03
Publication date: 1975-08-05
Anticipated expiration: 1992-08-05
Also published as: DE2522436C3; CA1018079A; DE2522436A1; DE2522436B2; GB1465024A

Abstract

A brake for a wheelchair takes the form of a helical spring surrounding a brake drum secured to and rotatable with one of the main wheels of the wheelchair. One end of the helical spring is secured to the frame structure of the chair and the other end is arranged to be coupled to an actuating mechanism for exerting a pulling force on the spring. This pulling force will circumferentially contract the spring into frictional engagement with the brake drum to thereby exert a frictional drag thereon and thereby brake the wheel. The actuating mechanism includes an over center linkage type arrangement so that a positive locking of the brake mechanism is maintained when it is desired to secure the wheelchair in a stationary position.

Description

United States Patent 191 Rodaway i 1 WHEELCHAIR HUB BRAKE [75] Inventor: Keith S. Rodaway, Culver City.

211 App]. No.: 475,526

[451 Aug. s, 1975 FOREIGN PATENTS OR APPLICATIONS 389.415 6/l92l Germany Nth/77 W Primary Eruminer-Trygve M. Blix Ass/sum! Erami'mW-EdWurd R. Kazenske Armrner. Agent. or FirmRulph B. Pastoriza [57] ABSTRACT A brake for a wheelchair takes the form of a helical spring surrounding a brake drum secured to and rotatable with one of the main wheels of the wheelchair. One end of the helical spring is secured to the frame structure of the chair and the other end is arranged to be coupled to an actuating mechanism for exerting u pulling force on the spring. This pulling force will circumferentiall contract the spring into frictional engagement with the brake drum to thereby exert a frictional drag thereon and thereby brake the wheel. The actuating mechanism includes an over center linkage type arrangement so that ll positive locking of the brake mechanism is maintained when it is desired to secure the wheelchair in a stationary position.

5 Claims. 4 Drawing Figures [52] US. Cl. 188/2 F; l88/77 W; 192/810. 280/242 WC; 297/DIG. 4 [51] Int. Cl B60t 1/06 [58} Field of Search t. 188/2 F, 77 W, 77 R; l92/8l C; 297/DIG. 4; 280/242 WC; 74/503. 5l8 520 [56] References Cited UNITED STATES PATENTS 545.492 9/l895 Hull Hill/77 W 554,234 2/l896 Brill 74/5l8 912,277 2/1909 Benson 74/520 1,306.766 6/l9l9 Kuijper l88/77 w 2.859.837 ll/l958 Mize 188/2 F PATENTEBAUB 5l975 3.8971857 WHEELCHAIR HUB BRAKE This invention relates generally to wheelchairs and more particularly to a combination wheelchair and hub brake assembly so that a patient can manually slow or otherwise control the speed of a wheelchair and ultimately brake it to a locked position.

BACKGROUND OF THE INVENTION Most conventional wheelchairs are provided with a wheel lock which prevents rotation of the main wheels when it is desired to maintain the wheelchair in a stationary position. Normally, these wheel locks take the form of a simple lever member pivoted to the frame structure adjacent the wheel periphery such that rocking movement of the lever causes one end to physically engage the wheel and prevent rotation thereof.

While wheel locks of the above type are effective in holding the wheelchair stationary, they do not serve as any type of brake for the wheelchair in the sense of an arrangement allowing a patient to slow his wheelchair or gradually brake the same to a full stop. Should a patient attempt to engage the wheel lock while the wheelchair is moving forwardly, the engaging link will simply rub against the periphery of the wheel or, on the other hand, should it become frictionally bound to the wheel, it will exert a sudden locking of the wheel which can cause the patient to pitch forward from the wheelchair.

BRIEF DESCRIPTION OF THE PRESENT INVENTION With the foregoing in mind, it is a primary object of the present invention to provide an improved hub brake assembly for a wheelchair wherein careful and precise control over the wheelchair can be had by a patient seated in the chair insofar as braking action is concerned.

A further important object and feature of this inven tion is to provide a hub brake assembly for a wheelchair so designed as not to result in any increase in the width of the wheelchair as measured from the outside of one main wheel to the outside of the other main wheel. Any such assembly that would cause an increase in the wheelchair width would severely limit the use of the wheelchair insofar as passing through narrow openings and the like.

In accord with the present invention, a brake drum means is coaxially secured to and rotatable with a main wheel of the wheelchair. A helical spring in turn is arranged to surround the brake drum means, one end of the spring being secured in a stationary position rela tive to the wheelchair frame. An actuating mechanism is coupled to the frame and coupled to the other end of the spring for exerting a pulling force on the spring to circumferentially contract the spring into frictional engagement with the brake drum means to exert a frictional drag thereon and thereby brake the wheel.

An additional similarly designed hub brake assembly is provided for the other wheel so that both wheels may be manually braked at will by a patient.

In the preferred embodiment, the actuating mechanism for contracting the helical spring incorporates an over center linkage arrangement so that when the brake is full on", the linkage is in an over center position so that it will be automatically retained in its fully locked position.

BRIEF DESCRIPTION OF THE DRAWINGS A better understanding of the invention will be had by now referring to a preferred embodiment thereof as illustrated in the accompanying drawings in which:

FIG. I is a side perspective view of a wheelchair incorporating the hub brake assembly of this invention;

FIG. 2 is an exploded perspective view of basic components making up the hub brake assembly used in FIG. I;

FIG. 3 is a fragmentary cross section of the various components of FIG. 2 in assembled relationship; and

FIG. 4 is a side elevational view in fragmentary form of certain of the basic components useful in describing the operation of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring first to FIG. I, there is shown a wheelchair having a frame structure 10 rotatably supporting first and second main wheels I1 and 12.

A hub brake assembly in the embodiment disclosed is associated with each of the first and second

main wheels

11 and 12. Since these assemblies are essentially the same, a detailed description of one will suffice for both. Thus, the hub assembly associated with the first main wheel 11 is designated generally at 13 and in cludes a circular plate 14 incorporating a braking mechanism which will be described in detail in conjunction with FIG. 2. This mechanism is arranged to be actuated by a rod 15 connecting to a linked element 16 pivoted to the frame structure for rocking movement as by a handle 17.

Referring now to FIG. 2, the details of the brake assembly associated with the circular plate 14 will become evident. As shown, the plate 14 forms part of the hub portion of the wheel II and is arranged to rotate therewith. As indicated, the spokes of the wheel may be secured to the periphery of the plate. The inside surface of the plate is shaped to define an annular cavity I8 coaxial with the wheel axis. Cooperating with the inside wall of the annular cavity 18 is an annular brake lining l9 fitted within the annular cavity in such a man ner that the overall width of the wheel hub assembly is not increased. Small screws or equivalent fastening means 20 may be provided for rigidly securing the brake lining 19 to the plate 14 for rotation therewith.

A helical spring 21 of rectangular cross section with the coils in side-by-side relationship has first and second radially extending

ends

22 and 23 terminating in hook portions serving as connecting means. This helical spring is dimensioned to surround the brake lining 19, the bias of the spring being essentially to result in a larger diameter of the individual coils than the outside diameter of the lining so that the inside flat surfaces of the coils are normally out of engagement with the brake lining.

The foregoing brake assembly described thus far is completed by the provision of an anchoring cover member 24 rigidly secured as by welding to the frame structure 10 and dimensioned to circumferentially fit within the annular cavity 18 to surround the spring 21 and brake lining. As shown, this cover member includes a peripheral connecting means in the form of a small opening 25 to which the first end 22 of the helical spring 21 is secured so that this end of the spring is held stationary relative to the frame 10. The cover member also includes a circumferentially spaced window opening 26 through which the second end 23 of the helical spring 21 passes when the elements are assembled. The actuating rod 15, a fragmentary portion of which is shown in FIG. 2 is arranged to be coupled to this second end 23 of the spring.

The foregoing described components are shown in assembled relationship in the cross section of FIG. 3 wherein the helical spring 21 is shown in frictional engagement with the brake lining 19 as a consequence of a pulling force being applied to the second end of the spring to circumferentially contract the same. A bolt 27 axially passes through the hub assembly to secure the entire assembly to the frame structure 10.

FIG. 4 illustrates the circular plate 14 with its front surface removed so as to expose the brake lining l9 and associated helical spring surrounding the same. In FIG. 4, the coupling of one end of the rod to the second end 23 of the helical spring is clearly illustrated. The other end of the rod 15 is shown connected to a link element 28 preferably in the form ofa C-shaped member centrally pivoted as at a first pivot point 29 to the frame structure 10. A second spaced pivot point 30 is defined at the end of one of the arms of the C-shaped member 28 for pivoted connection to the other end 32 of the rod 15. In the preferred embodiment, the C-shaped member 28 includes a third pivot point at the end of the other arm the purpose for which will become clearer as the description proceeds.

The handle 17 described in FIG. 1 is secured to the Oshaped member 28 to enable rocking of the same about the pivot point 29 relative to the frame 10.

It will be noted in FIG. 4 that if a straight center line designated CL. and identified by numeral 34 is drawn between the one end 31 of the rod 15 at the point it is coupled to the second end 23 of the spring and the first pivot point 29, the second spaced pivot point 30 for the other end of the rod 15 is positioned below this straight center line when the helical spring is in a relaxed position wherein its inner peripheral surface is out of engagement with the brake lining 19.

If the handle 17 is now moved to the dotted line position indicated at 17' to rock the C-shaped member 28 in a counter-clockwise direction about the first pivot point 29, a pulling force will be exerted on the rod 15 and thus exerted on the second end 23 of the helical spring to circumferentially contract the same into frictional engagement with the periphery of the brake lining 19. This rocking movement of the C-shaped mem her is sufficient to move the second pivot point 30 above the straight center line 34 to result in an over center action. in this respect the frame structure is provided with a stop means 35 blocking further rocking movement of the handle 17 and thus the C-shaped member so that the member is held in its maximum rocked position in the one direction as described to lock the braking action.

In the event a patient in the wheelchair should wish to operate the brake by a forward movement of the handle 17 rather than a pulling towards a rearward direction, the other end 32 of the connecting rod can be disengaged from the second pivot point 30 and coupled to the third pivot point 33 on the other arm of the C-shaped member 28. When the handle 17 is in the dotted line position 17', this third pivot point 33 assumes a position the same distance from the end of the spring 23 as the second pivot point 30 when the handle 17 is in the solid line position. It will then be evident that forward movement of the handle 17 from the dotted line position 17' to the solid line position will exert a pulling force on the connecting rod 15 to thereby circumferentially contract the helical spring into frictional engagement with the brake lining 19. Moreover, the arrangement is such that the third pivot point 33 will move below the center line 34 when operated in this manner so that again an over centering action takes place.

The assembly is completed by the provision of a turn buckle 36 in the connecting rod 15 in order to enable adjustment of its length so that the point at which frictional engagement of the spring with the brake lining takes place relative to the position of the handle 17 and thus the rocked position of the C-shaped member 28 can be realized.

OPERATION The operation of the hub brake assembly will be evident from the foregoing description. Normally, and as described heretofore, the overall length of the connecting rod 15 is adjusted by the turn buckle 36 such that when the other end 32 of the rod 15 is connected to the second spaced pivot point 30, the helical spring will be out of engagement with the brake lining 19 when the handle 17 is in the solid line position as shown in FIG. 4. A patient in the wheelchair can thus roll the chair about a room or outside in the usual manner without any interference from the hub brake assembly. When the user wishes to brake the wheelchair, he can pull back on the handle 17 with a given force which will determine the degree of frictional engagement of the helical spring with the brake lining. Complete locking of the brake is effected, as described, by moving the handle l7 completely to the dotted line position 17' to effect the over centering action of the connecting rod 15.

The same operation obtains when the second end 32 of the connecting rod 15 is initially connected to the third spaced pivot point 33 on the C-shaped member 28 wherein the unlocked position of the brake is assumed when the handle 17 is initially in the dotted line position indicated at 17' in FIG. 4. As described, braking action can be effected in desired degrees by then urging the handle l7 forwardly.

In the complete preferred embodiment, a corresponding hub brake assembly is provided for the second wheel 12 as described in FIG. 1, so that the patient or other user of the wheelchair can brake both wheels simultaneously if he desires.

The rectangular cross section of the helical spring and the provision of the spring itself provides a very large area of frictional engagement as compared to a circular cross section band or spring. Thus, very positive and accurate braking can be realized.

From the foregoing description, it will thus be evident that the present invention has provided an improved braking system for a wheelchair which can be used by itself or in conjunction with the normal wheel locking lever arrangements presently available.

What is claimed is:

1. In combination with a wheelchair including a frame structure rotatably supporting first and second main wheels, a hub brake assembly including:

a. a circular plate forming part of the hub portion of said first wheel for rotation therewith, said plate defining an annular cavity coaxial with the wheel axis;

b an annular brake lining fitted within said annular cavity so that the overall width of the wheel hub assembly is not appreciably increased;

c. a helical spring of rectangular cross section surrounding said brake lining and including radially extending first and second ends terminating in connecting means;

dv an anchoring cover member secured to said frame structure coaxial with the axis of rotation of said wheel and dimensioned to circumferentially fit within said annular cavity without engaging said circular plate to surround said spring and brake lining, said cover member including a peripheral connecting means to which said first end of said spring is secured and a peripheral window opening through which said second end of said spring passes;

e. a rod having one end coupled to said second end of said spring; and,

fl an actuating means including a link element piv oted at a first pivot point to said frame structure and including a spaced second pivot point connected to the other end of said rod such that rocking movement of said link element exerts a pulling movement on said rod to circumferentially contract said helical spring into circumferential engagement with said annular brake lining thereby exerting a frictional drag thereon to brake said wheel,

2. The subject matter of claim 1, in which said second spaced pivot point is positioned to one side ofa straight center line passing through the coupling point of said one end of said rod and said first pivot point, the rocking movement of said element being sufficient to move said second pivot point to the other side of said straight center line to result in an over center action, said frame structure including stop means blocking further rocking movement of said element so that it is held in its maximum rocked position by the tension exerted by said helical spring to thereby lock the braking action.

3. The subject matter of claim 1, in which said link element comprises a C-shaped member, said first pivot point being at its central area and said spaced second pivot point being at the end of one of the arms of said member below a straight center line passing through the coupling point of said one end of said rod and said first pivot point. the rocking movement of said member being sufficient to move said second pivot point above said straight line to result in an over center action. said frame structure including stop means blocking further rocking movement of said C-shaped member so that the member is held in its maximum rocked position in one direction to lock the braking action, said C-shaped member including a third spaced pivot point at the end of the other of its arms so that said other end of said rod can be disconnected from the second pivot point and connected to the third pivot point to thereby permit rocking of the member in an opposite direction to effeet a pulling force on the rod, the rocking movement in said opposite direction being sufficient to move said third pivot point from above said center line to an over center position below said line whereby said assembly can be arranged to provide braking action by rocking movement in one direction or the other.

4. The subject matter of claim 3, in which said rod incorporates a turn buckle intermediate its ends to enable adjustment of its overall length.

5. The subject matter of claim 4, including an additional hub brake assembly associated with said second main wheel incorporating similar components to said first mentioned hub brake assembly whereby braking action can be effected from either side of said wheelchair.

Claims

1. In combination with a wheelchair including a frame structure rotatably supporting first and second main wheels, a hub brake assembly including: a. a circular plate forming part of the hub portion of said first wheel for rotation therewith, said plate defining an annular cavity coaxial with the wheel axis; b. an annular brake lining fitted within said annular cavity so that the overall width of the wheel hub assembly is not appreciably increased; c. a helical spring of rectangular cross section surrounding said brake lining and including radially extending first and second ends terminating in connecting means; d. an anchoring cover member secured to said frame structure coaxial with the axis of rotation of said wheel and dimensioned to circumferentially fit within said annular cavity without engaging said circular plate to surround said spring and brake lining, said cover member including a peripheral connecting means to which said first end of said spring is secured and a peripheral window opening through which said second end of said spring passes; e. a rod having one end coupled to said second end of said spring; and, f. an actuating means including a link element pivoted at a first pivot point to said frame structure and including a spaced second pivot point connected to the other end of said rod such that rocking movement of said link element exerts a pulling movement on said rod to circumferentially contract said helical spring into circumferential engagement with said annular brake lining thereby exerting a frictional drag thereon to brake Said wheel.

2. The subject matter of claim 1, in which said second spaced pivot point is positioned to one side of a straight center line passing through the coupling point of said one end of said rod and said first pivot point, the rocking movement of said element being sufficient to move said second pivot point to the other side of said straight center line to result in an over center action, said frame structure including stop means blocking further rocking movement of said element so that it is held in its maximum rocked position by the tension exerted by said helical spring to thereby lock the braking action.

3. The subject matter of claim 1, in which said link element comprises a C-shaped member, said first pivot point being at its central area and said spaced second pivot point being at the end of one of the arms of said member below a straight center line passing through the coupling point of said one end of said rod and said first pivot point, the rocking movement of said member being sufficient to move said second pivot point above said straight line to result in an over center action, said frame structure including stop means blocking further rocking movement of said C-shaped member so that the member is held in its maximum rocked position in one direction to lock the braking action, said C-shaped member including a third spaced pivot point at the end of the other of its arms so that said other end of said rod can be disconnected from the second pivot point and connected to the third pivot point to thereby permit rocking of the member in an opposite direction to effect a pulling force on the rod, the rocking movement in said opposite direction being sufficient to move said third pivot point from above said center line to an over center position below said line whereby said assembly can be arranged to provide braking action by rocking movement in one direction or the other.