WO1997031606A1

WO1997031606A1 - Side frame for a wheelchair and a wheelchair incorporating same

Info

Publication number: WO1997031606A1
Application number: PCT/AU1996/000113
Authority: WO
Inventors: James Herder; Michael Jones; Aldo Contarino; John Chapman
Original assignee: Pacific 21 Pty. Ltd.
Priority date: 1996-03-01
Filing date: 1996-03-01
Publication date: 1997-09-04
Also published as: AU4709996A

Abstract

A wheelchair (12) is made from plastics material and is composed of two side frames (10 and 10') each characterised by a single integral unit (14) which comprises a plurality of integrally connected elongate elements (16, 18, 20, 22, 24 and 26). Each of the elongate elements (16-26) comprises a planar web (W) and a pair of flanges (F1 and F2) formed integrally along opposed longitudinal edges of the web (W) so that each elongate element has a substantially I-shaped or H-shaped transverse section. The flanges are radiused at the connecting points of the elements. The element (16) is provided with a recess (28) so as to couple to a front wheel caster (32). A web (38) is formed integrally with and spans second and third elongate elements (18 and 20). The web (38) is provided with three holes (39, 40 and 41) and is sandwiched between two blocks with corresponding holes to provide bulk for securing an axle of rear wheel (34). The axle passing through any one of the three holes any one of which can receive an axle of a rear wheel (34). The substantially identical side frames (10 and 10') can be connected together by a folding mechanism (42) to form a wheelchair structure. Fabric seat (56) and back support (60) are attached at opposite sides of the side frames (10 and 10').

Description

Title

SIDE FRAME FOR Λ WHEELCHAIR AND A WHEELCHAIR

INCORPORATING SAME

Field of the Invention This invention relates to a side frame for a wheelchair and a wheelchair constructed from and incorporating two such side frames.

Background of the Invention

Wheelchairs have been known for a considerable time and come in a multitude of different forms to address specific needs of the users.

Hitherto, wheelchairs have generally comprised a metal tubular frame having secured thereto four wheels, a brake mechanism, a seat, a back rest and a foot rest. The metal tubular frame may be made of two distinct side frames which are coupled together by either a fixed or folding structure.

Typically, the metal frame for the wheelchair is fabricated from metal tubing and generally includes welded joints and bolted connections. Components such as castor wheels, handles, foot rests, brakes and arm rests are usually bolted to the frame resulting in a vehicle of cumbersome and elaborate appearance. More importantly, wheelchair frames constructed in this manner are susceptible to fatigue at the joints arising from stress concentrations and weld trauma. Also, the rigidity of the metal frame increases the stress on the frame joints as well as providing an uncomfortable ride for the wheelchair occupant.

An alternate form of construction for the wheelchair frame is described in US 5,382,036 (COUNTS ET AL) . This patent describes a wheelchair frame made from fibre resin tubular members. One object of the invention described in this US patent is to provide a graphite/epoxy tubular wheelchair frame assembly and method for manufacturing the same which produces a wheelchair frame having greater strength and better resistance to shock or impact loading than the conventional metal frame wheelchairs. However, an acknowledged problem with the use of hollow fibre- reinforced tubular members is their inability to withstand transverse clamping forces or radially inward forces which will be applied when wheelchair components such as castors are attached to the frame. In order to overcome this deficiency, the patentee proposes to flatten the tubular members in the region where a component is to be attached to the frame and uses a specialised clamping assembly which limits the transverse clamping forces that can be applied to the tubular frame.

It is an object of the present invention to provide a side frame for a wheelchair and a wheelchair incorporating such side frames that are simple and relatively inexpensive to manufacture and of rugged construction which is less susceptible to fracture and breakage than the conventional metal tubular framed wheelchairs or the above-described fibre reinforced tubular wheelchair frame.

Summary of the Invention According to a first aspect of the present invention there is provided a side frame for a wheelchair, said side frame formed as a single integral unit which includes wheel coupling means for allowing coupling with one or more wheel or castor assemblies, and joining structure coupling means to which one side of a joining structure of a wheel chair can be coupled, said side frame configured to act as either a left hand side frame or right hand side frame, whereby, in use, a pair of substantially identical ones of said side frames can be coupled together by a joining structure coupled to the joining structure coupling means of each side frame and a plurality of wheels can be coupled to the wheel coupling means of each side frame to form a wheelchair like structure.

Preferably said single integral unit comprises a plurality of integrally connected elongate elements.

Preferably said elongate elements are solid.

Preferably said elongate elements, at the region of mutual connection, are continuously curved.

Preferably each elongate element comprises a planar web and at least one flange formed integrally therewith and extending in a plane substantially perpendicular to that containing said web.

Preferably one of said at least one flanges extends along a longitudinal edge of said planar web.

Preferably said one, or another one, of said at least one flanges is disposed inboard of opposite longitudinal edges of said web.

Preferably said flanges can extend laterally from only one or both planar surfaces of said web.

Preferably each elongate element is provided with two flanges, each flange extending along opposite longitudinal edges of said web so that said elongate element has a substantially I-shaped or H-shaped transverse section.

Preferably said wheel coupling means comprises a front wheel coupling recess for receiving a post about which a front wheel can swivel, said recess being formed in a first one of said elongate elements, which, when said side frame is in use incorporated into a wheelchair, it is disposed substantially vertically.

Preferably said wheel coupling means further includes second and third ones of said elongate elements, said second and third elongate elements having respective lengths which are spaced apart to, or between which, a rear wheel can be connected to said side frame.

Preferably a fourth of said elongate elements is integrally connected to said first, second and third elongate elements and extends substantially perpendicularly to said first element, said fourth elongate element having one end adjacent said front wheel coupling means.

Preferably said side frame comprises an integral portion spanning said second and third elongate elements to which said rear wheel assembly can be connected.

Preferably said integral portion comprises a web like structure provided with one or more holes for receiving an axle of said rear wheel or a rear wheel bracket. In an alternate embodiment said integral portion consists of a length of said fourth elongate element between said second and third elements.

Preferably said fourth elongate element forms a first part of said joining structure coupling means.

Preferably a fifth of said elongate elements is disposed above and extends parallel to said fourth elongate element and is integrally coupled to said first and second elongate elements, wherein said fifth elongate element forms a second part of said joining structure coupling means.

Preferably a sixth of said elongate elements is disposed above and extends parallel to said fifth elongate element, said sixth elongate element adapted to form or support an arm rest of a wheelchair incorporating said side frame.

Preferably said third elongate element extends beyond, and is integrally connected to, said sixth elongate element, and is provided at an end distant said fourth elongate element with an integrally formed handle by which a person can grip and push a wheelchair incorporating said side frame.

Preferably one or more of said elongate elements is provided with one or more transversely extending holes for receiving fastening means to allow the connection of assorted wheelchair components to said side frames.

Preferably said holes are formed simultaneously with said single integral unit.

Preferably said single integral unit is formed by molding or casting a setable molten or liquid like substance.

Preferably said molten or liquid like substance comprises a plastics material.

Preferably the plastics material is polypropylene or nylon.

Alternately, said molten or liquid like material comprises a molten light-weight metal such as aluminium.

According to a second aspect of the present invention there is provided a wheelchair comprising: first and second side frames in accordance with a first aspect of the present invention; a joining structure for connecting said first and second side elements together in a side by side juxtaposition, opposite sides of said structure being coupled to the joining structure coupling means of each side frame ; and, first and second sets of a front wheel assembly and rear wheel assembly, said first set of wheel assemblies being coupled to the wheel coupling means of said first side frame and said second set of wheels being coupled to the wheel coupling means of said second side frame.

Preferably one of the front and rear wheel assemblies of each set is provided with a post about which that one wheel can swivel, and a resilient sleeve for receiving said post and adapted to be seated in its wheel coupling means, whereby, in use, said sleeve allows the tilting of said post from a first position when said wheelchair is unoccupied to a second position when said wheelchair is occupied so as to provide a trail for said one wheel.

Preferably said resilient sleeve comprises a tubular member composed of a resilient material.

Preferably said resilient material is a cross-linked elas opolymer.

In an alternate construction, said resilient sleeve comprises a helical spring.

Preferably said joining structure includes a seat which can be fastened at its opposite sides to said joining structure coupling means of said first and second side frames.

Preferably said joining structure further includes a folding mechanism which can be fastened at its opposite sides to said joining structure coupling means of said first and second side frames whereby said wheelchair can be folded so as to vary the spacing between said first and second side frames.

Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which: Brief Description of the Drawings

Figure 1 is a side view of a first embodiment of a side frame of a wheel chair in accordance with the present invention;

Figure 2 is an enlarged perspective view of a portion of the side frame shown in Figure 1;

Figure 3 is a perspective view of a wheelchair incorporating the side frame shown in Figures 1 and 2;

Figure 4 is an exploded view of a portion of the side frame 20 of the wheel assembly as fixed;

Figure 5 is an end view of a folding mechanism for joining two side frames together to form a wheel chair structure;

Figure 6 is a side view of a second embodiment of the side frame; and,

Figure 7 is a schematic representation of a second embodiment of a front wheel assembly for a wheelchair comprised of the side frames.

Detailed Description of the Preferred Embodiments

With particular reference to Figures 1-3, it can be seen that a side frame 10 for a wheelchair 12 is composed of a single integral unit 14 which comprises a plurality of integrally connected elongate elements 16, 18, 20, 22, 24, and 26.

As shown most clearly in Figure 2, each of the elongate elements 16-26 comprises a planar web W and a pair of flanges FI and F2 formed integrally along opposed longitudinal edges of the web W. The flanges FI and F2 extend in planes substantially perpendicular to the plane containing the web W. Further, the flanges FI and F2 extend on both sides of the web W so that each of the elements 16-26 has a substantially I-shaped or H-shaped transverse section. As is further apparent from Figure 2, each of the elongate elements 16-26 is solid and continuously curved at a region R of mutual connection.

The side frame 10 also includes wheel coupling means for coupling of front and rear wheels or castors. The wheel coupling means includes a front wheel coupling recess 28 which is formed at the lower end of the first element 16. The recess 28 (together with a resilient sleeve, as will be described later) is able to receive a post 30 (shown in Figure 4) about which a front wheel 32 can swivel.

The wheel coupling means also includes the second and third elongate elements 18 and 20 respectively which have respective lengths 18A and 20A that are spaced apart to, or between, which rear wheel 34 of the wheelchair 12 can be connected.

The fourth element 22 is integrally connected to the first, second and third elements 16, 18 and 20 and extends substantially perpendicularly to a lower length 16A of the first element 16. Fifth element 24 is disposed above and extends parallel to the fourth element 22 and is integrally coupled to the first, second and third elements 16, 18 and 20. The fourth and fifth elements 22 and 24 form first and second parts of a joining structure coupling means to which, as will be explained in greater detail below, a seat and/or fixed or folding mechanism can be connected so as to form a wheelchair.

The third element 20 is provided with a second length 20B which extends from the first length 20A but is inclined toward the first element 16. Extending substantially vertically from the second length 2OB is a third length 20C. Fourth length 20D of the third element 20 extends upwardly and slightly rearwardly of the third element 20C. A handle 36 is formed integrally with the fourth length 20D and extends substantially perpendicularly thereto in a rearward direction.

The first element 16 includes a first length 16A in which is formed the front wheel coupling recess 28 which extends in the upward direction and inclined slightly rearwardly of the vertical. A second length 16B of the first element 16 extends contiguously from the first length 16A in a generally upward direction but inclined rearwardly of the first element 16A.

The sixth element 26 is disposed above and extends parallel to the fifth element 24 and is integrally connected at one end to the second length 16B of the first element 16 and at an opposite end to the third element 20 at the junction of lengths 20C and 20D. The sixth element 26 can by itself form an arm rest of the wheelchair 12. Alternatively, another arm rest such as a padded arm rest or specially configured arm rest can be supported on the sixth element 26.

In the embodiment shown in Figure 1, the side frame 10 also includes an integral portion in the form of a web like structure 38 which spans lengths 18A and 20A. The web like structure 38 is provided with three holes 39, 40 and 41 and is sandwiched between two blocks (not shown) with corresponding holes. The blocks are typically of a width such that when one face abuts the web 38 its opposite face is flush with the flanges FI or F2 of the adjacent elongate elements 18, 20 and 22. The blocks can be fastened to the web 38 by screws and provide bulk for securing an axle of rear wheel 34. The axle of the rear wheel 34 passes through any one of the holes 39, 40 or 41. In the embodiment shown in Figure 6, the web like structure 38 has been omitted and a rear wheel can be connected by means of a bracket spanning and connected at opposite ends to the lengths 18A and 20A.

In yet a further variation (not shown) , the integral portion of the side frame which spans the second and third elements 18 and 20 to which a rear wheel can be coupled may include a length 22B of the fourth element 22. In this embodiment again a hole can be formed in the length 22B for receiving an axle of the rear wheel 32 or a bracket may be clamped to the length 22B for supporting the rear wheel 34.

As seen in Figures 1 and 2, a plurality of holes H are provided in the elongate members 16-26 for receiving fastening means to allow for the connection of other components to the side frame 10. The holes H extend through the web portion W of each elongate element in a direction transverse to the length of the element. It is envisaged that the holes will be formed simultaneously with the side frame 10. However, it is possible to form the holes by drilling after formation of the side frame 10.

It is envisaged that the side frame 10 will be formed by molding or casting a setable molten or liquid like substance such as polypropylene plastics, nylon, or other plastics materials or light weight and preferably non- ferrous metals such as aluminium.

As seen in Figure 3 , the wheelchair 12 can be constructed by connecting side frames 10 and 10' together. The side frames 10 and 10' are coupled together by a joining structure in the form of a folding mechanism 42, shown most clearly in Figure 5. The precise structure and configuration of the folding mechanism 42 is not an important or critical feature of the present invention and is merely required to join the two side frames 10 and 10' together in a manner so that the wheelchair 12 can be folded when not in use for storage or transport and then unfolded for use. Indeed, in an alternative embodiment (not shown), the side frames 10 and 10' can be connected together by a fixed structure which does not allow folding of the wheel chair 12.

The folding mechanism 42 comprises two pairs of cross members 43 and 44. A lower end of each of the cross members 43 is pivotally coupled to the fourth element 22 of side frame 10. The opposite end of each cross member 43 is pivotally coupled to one end of respective links 46. The other end of link 46 is pivotally coupled to the fifth element 24' of the side frame 10' . A lower end of each of the cross members 44 is pivotally coupled to the fourth element 22' of side frame 10' . The upper end of each of the cross members 44 is pivotally coupled to one end of respective links 48. The other end of link 48 is pivotally coupled to the fifth element 24 of side frame 10. Respective adjacent ones of the cross members 43 and 44 are connected along a common pivot axis 50. One or more transverse members 52 can be formed integrally between the cross members and each pair. The connection of the cross members 43, 44 and links 46 and 48 to the corresponding elongate elements in the side frames 10 and 10' is made by way of brackets or clamps 54 which are secured by means of screw fasteners to the fifth or fourth elements. A link or strap 55 is connected between the lower ends of adjacent ones of cross members 43 and 44 to limit the degree of pivoting about pivot axis 50.

A fabric seat 56 is attached at opposite sides to the fifth elements 24 and 24' by rails 58 which are bolted or screwed via holes H to the fifth elements 24 and 24'. The rails 58 are configured to seat in the recess formed between the flanges Fl and F2 and web W on the outside of the respective elements 24 and 24'. The rails 58 apply pressure against the fabric of seat 56 by means of bolts or screws .

A fabric back support 60 is similarly attached by rails 62 to the fourth lengths 20D and 20'D.

A manually operable brake mechanism 64 is also fastened to each of the clamps 58 to brake the rotation of the rear wheels 34.

Foot rests 66 are clamped to first lengths 16A and 16'A of the first elements 16 and 16' . Each foot rest 66 comprises an arm 68 which is bent so as to extend forward and downwardly of the respective side frame to which it is connected. At the end of each arm 68 is a forward extending spigot 70 on which a foot plate 72 is frictionally captured for pivoting about the length thereof. Frictional capture is provided by forming the foot plate 72 with a sleeve 74 having alternating concavities which envelope the spigot 70.

The clamping of the foot rests 66 to the first elements 16 and 16' is achieved by splitting the upper end of each arm 68 into two parts 76 and 78 which, when fastened together by mechanical fastener grip about opposite sides of the flange Fl of the respective first elements 16 and 16'.

Rubber hand grips 80 can be push-fitted onto the handles 38 and 38' .

Figure 4 illustrates the coupling arrangement for the front wheels or castors 32. Each front wheel 32 is supported by a bifurcated arm 82 the upper end of which is provided with a hole 84 into which is press-fitted the post 30. Post 30 is inserted into a resilient sleeve 86 which in turn is seated in the recess 28. The recess 28 is formed in a housing 88 which is formed as part of and integrally with the first element 16. A second separate housing 90 can be fastened by bolts 92 to the housing 88 to capture the post 30 and sleeve 86. To this end, the housing 90 is provided with a recess of similar configuration to the recess 28. Recess 28 is provided with upper and lower semi-circular flanges 94 and 96. The lower flange 94 is located at the bottom of recess 28. The upper flange 96 however is located slightly below the uppermost extent of recess 28. Identical flanges (not shown) are also provided in the recess in housing 90. A cap 98 is knocked into the sleeve 86 and above that is located a washer or disc 100. When the housings 88 and 90 are connected together by the bolts 92, the sleeve 86 is disposed between the upper and lower flanges 94 and 96. The top of the cap 98 and the washer 100 are captured within the recess 28 above the upper flange 96.

Sleeve 86 can be made from rubber and elastopolymer. The resilience and elasticity of the sleeve 86 allows the swivel axis of the castor (i.e. the axis of post 30) to incline away from the axis of the housing 88/90 when the wheel 32 is under load. The direction of the inclination being opposite to the direction of the trail of the bifurcated arm 82. Such inclination minimises castor flutter and thus acts to stabilise the castor. Additionally, the resilience of the sleeve 86 functions as a cushion to absorb impacts to the front wheel 32.

In an alternative embodiment shown in Figure 7, the post 30 is split into two separate components 30A and 30B having abutting ends which are configured to allow relative pivoting of component 30A and 30B. Component 30A is press- fitted into the bifurcated arm 82. The resilient sleeve 86' in this instance is in the form of a helical spring which surrounds the component 30A and at least a length of the component 30B. The sleeve 86' has the same effect as the sleeve 86 in that it allows the inclination of the swivel axis of the wheel 82 away from the axis of the housing 88/90 when the castor wheel 32 is under load.

An alternative embodiment of the side frame 10 is shown in Figure 6. The main differences between this embodiment and that shown in Figure 1 is that the lengths 18B and 20B of the second and third elements 18 and 20 are inclined toward each other and converge so as to integrally couple with each other as well as the fourth elongate element 24. Also, in the embodiment in Figure 6, the web like structure 38 has been omitted and coupling of the rear wheel 34 is made by means of a bracket (not shown) which spans, and is connected to, lengths 18A and 20A.

It will be clear from the above description that embodiments of the present invention enjoy numerous advantages and benefits over the prior art. As the side frame 10 is made as a single integral unit the problems associated with connecting separate structural elements as occurs with conventional metal framed wheelchairs is avoided. The rounded or continuously curved corners at the junction of the elements 16-26 provides stress relief in the frame 10. Forming the elements 16-26 so as to have an I-shaped or H-shaped transverse section gives each element individually and the side frame 10 as a whole a substantial torsional strength. Further, as the side frame 10 is made as a single unit, the manufacturing time is relatively short compared with that required for fabricating metal frames and the material is substantially homogenous throughout. With metal framed wheelchairs, the requirement for welds produces discontinuities in the structure of the metal which gives rise to stress concentrations and increases the likelihood of fractures. As the side frame 10 can be used for both the left hand sides of a wheelchair 12, the associated manufacturing costs are also low as only one mould is required to make both side frames for a wheelchair 12.

The type of screw fastener used to attach components of the wheel chair 12 to side frame 10 and 10' may be either of the bolt and nut variety or in the form of a tapered screw. When a tapered screw is used, and the side frames 10, 10'

are of plastics material, the screw coacts with (ie. bites into) the side walls of holes H through which they pass.

The inclination of the swivel axis of the front wheels or castors 32 substantially assists in stabilising the wheels or castors and in this way greatly improves the manoeuvrability of the wheelchair 12. It is possible to manufacture the wheelchair 12 from almost exclusively plastics materials with possible exceptions being to the bifurcated arm 82, rear wheels 34 and fastening bolts and screws. However, such components can conveniently be made from non-ferrous metals. Thus, the wheelchair 12 can be essentially rustproof and therefore can be taken directly into a shower by an occupant without the need for transferring from for example a conventional metal-framed wheelchair to another support or chair disposed within the shower. Also, by making the vast majority of parts of the wheelchair 12 from a plastics material, the need for oil- based lubricants is virtually eliminated. Lubrication can instead be provided by use of talc or graphite.

When the side frame 10 is made from plastics material, it will have a lower degree of rigidity than conventional metal frames and therefore when incorporated into a wheelchair 12 will provide a smoother, more comfortable ride.

Now that embodiments of the present invention have been described in detail it will be apparent to those skilled in the relevant arts that numerous modifications and variations may be made without departing from the basic inventive concepts. For example, the specific shape and configuration of the side frame 10 and elements 16-26 can obviously be modified from that shown in the accompanying drawings. For example, an additional element can be formed integrally with, and extending between the fifth elongate element 24 and sixth elongate element 26. Additionally, the space or void found between various elements within the frame 10 can be filled with a web of material of the same type from which the side frame 10 is made. Also, the elongate elements 16-26 can be made of a transverse section having a shape other than I-shaped or H-shaped.

All such modifications and variations are deemed to be within the scope of the present invention the nature of which is to be determined from the foregoing description.

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS;-

1. A side frame for a wheelchair, said side frame formed as a single integral unit which includes wheel coupling means for allowing coupling with one or more wheel or castor assemblies, and joining structure coupling means to which one side of a joining structure of a wheel chair can be coupled, said side frame configured to act as either a left hand side frame or right hand side frame, whereby, in use, a pair of substantially identical ones of said side frames can be coupled together by a joining structure coupled to the joining structure coupling means of each side frame and a plurality of wheels can be coupled to the wheel coupling means of each side frame to form a wheelchair like structure.

2. A side frame according to claim 1, wherein said single integral unit comprises a plurality of integrally connected elongate elements.

3. A side frame according to claim 2, wherein said elongate elements, at the region of mutual connection, are continuously curved.

. A side frame according to claim 3, wherein each elongate element comprises a planar web and at least one flange formed integrally therewith and extending in a plane substantially perpendicular to that containing said web.

5. A side frame according to claim 4, wherein one of said at least one flanges extends along a longitudinal edge of said planar web.

6. A side frame according to claim 4, wherein said one, or another one, of said at least one flanges is disposed inboard of opposite longitudinal edges of said web.

7. A side frame according to claim 5, said flanges can extend laterally from only one or both planar surfaces of said web.

8. A side frame according to claim 7, wherein each elongate element is provided with two flanges, each flange extending along opposite longitudinal edges of said web so that said elongate element has a substantially I-shaped or H-shaped transverse section.

9. A side frame according to claim 8, wherein said elongate elements are solid.

10. A side frame according to claim 2, wherein said wheel coupling means comprises a front wheel coupling recess for receiving a post about which a front wheel can swivel, said recess being formed in a first one of said elongate elements, which, when said side frame is in use incorporated into a wheelchair, it is disposed substantially vertically.

11. A side frame according to claim 10, wherein said wheel coupling means further includes second and third ones of said elongate elements, said second and third elongate elements having respective lengths which are spaced apart to, or between which, a rear wheel can be connected to said side frame.

12. A side frame according to claim 11, wherein a_. fourth of said elongate elements is integrally connected to said first, second and third elongate elements and extends substantially perpendicularly to said first element, said fourth elongate element having one end adjacent said front wheel coupling means.

13. A side frame according to claim 12, wherein said side frame comprises an integral portion spanning said second and third elongate elements to which said rear wheel assembly can be connected.

1 . A side frame according to claim 13 , wherein said integral portion comprises a web like structure provided with one or more holes for receiving an axle of said rear wheel or a rear wheel bracket.

15. A side frame according to claim 13 , wherein said integral portion consists of a length of said fourth elongate element between said second and third elements .

16. A side frame according to claim 12, wherein said fourth elongate element forms a first part of said joining structure coupling means.

17. A side frame according to claim 16, wherein a fifth of said elongate elements is disposed above and extends parallel to said fourth elongate element and is integrally coupled to said first and second elongate elements, wherein said fifth elongate element forms a second part of said joining structure coupling means.

18. A side frame according to claim 17, wherein a sixth of said elongate elements is disposed above and extends parallel to said fifth elongate element, said sixth elongate element adapted to form or support an arm rest of a wheelchair incorporating said side frame.

19. A side frame according to claim 18, wherein said third elongate element extends beyond, and is integrally connected to, said sixth elongate element, and is provided at an end distant said fourth elongate element with an integrally formed handle by which a person can grip and push a wheelchair incorporating said side frame.

20. A side frame according to claim 2, wherein one or more of said elongate elements is provided with one or more transversely extending holes for receiving fastening means to allow the connection of assorted wheelchair components to said side frames.

21. A side frame according to claim 20, wherein said holes are formed simultaneously with said single integral unit.

22. A side frame according to claim 3, wherein said single integral unit is formed by molding or casting a setable molten or liquid like substance.

23. A side frame according to claim 22, wherein said molten or liquid like substance comprises a plastics material.

24. A side frame according to claim 23, wherein said plastics material comprises polypropylene or nylon.

25. A side frame according to claim 22, wherein said molten or liquid like material comprises a molten light¬ weight metal such as aluminium.

26. A wheelchair comprising: first and second side frames in accordance with claim 1; a joining structure for connecting said first and second side elements together in a side by side juxtaposition, opposite sides of said structure being coupled to the joining structure coupling means of each side frame; and, first and second sets of a front wheel assembly and rear wheel assembly, said first set of wheel assemblies being coupled to the wheel coupling means of said first side frame and said second set of wheels being coupled to the wheel coupling means of said second side frame.

27. A wheelchair according to claim 26, wherein one of the front and rear wheel assemblies of each set is provided with a post about which that one wheel can swivel, and a resilient sleeve for receiving said post and adapted to be seated in its wheel coupling means, whereby, in use, said sleeve allows the tilting of said post from a first position when said wheelchair is unoccupied to a second position when said wheelchair is occupied so as to reduce flutter of said one wheel.

28. A wheelchair according to claim 27, wherein said resilient sleeve comprises a tubular member composed of a resilient material.

29. A wheelchair according to claim 28, wherein said resilient material is a cross-linked elastopolymer.

30. A wheelchair according to claim 28, wherein said resilient sleeve comprises a helical spring.

31. A wheelchair according to claim 30, wherein said joining structure further includes a folding mechanism which can be fastened at its opposite sides to said joining structure coupling means of said first and second side frames whereby said wheelchair can be folded so as to vary the spacing between said first and second side frames.