WO2011141698A1

WO2011141698A1 - Collapsible support frame

Info

Publication number: WO2011141698A1
Application number: PCT/GB2011/000716
Authority: WO
Inventors: Samuel Blackburn Pearce
Original assignee: Jelly Products Ltd
Current assignee: Jelly Products Ltd
Priority date: 2010-05-11
Filing date: 2011-05-11
Publication date: 2011-11-17
Anticipated expiration: 2012-11-11

Abstract

A collapsible support frame (10) for carrying a load. The support frame (10) in an erect configuration comprising a pair of collapsible support arms (12). Each of the support arms (12) is drivingly coupled at or towards a first end to the other support arm (12) for pivotable movement relative thereto and pivotably coupled at or towards a second end to a handle (16). The support arms (12) are curved to define an open support structure to carry a load. The support frame (10) also comprises a pair of support limbs (18). Each support limb (18) carries a wheel (20) at or towards a first end and is coupled at or towards a second end to a respective support arm (12) for pivotal movement relative thereto. The support limbs (18) in use of the support frame (10) in an erect configuration extend from the respective support arms (12) so as to space the wheels (20) from each other and provide ground engaging support below the open support structure. The support frame (10) also comprises a collapsible linkage assembly (22) extending between the support arms (12) and the support limbs (18) to control pivoting movement of the support limbs (18) relative to the support arms (12). Each of the support arms (12) is drivingly coupled such that pivotable movement of one support arm (12) relative to the other support arm (12) drives pivotable movement of the other support arm (12) relative to the one support arm (12). The linkage assembly (22) is collapsible on collapsing of the support arms (12) to pivot the support limbs (18) relative to the support arms (12) so as to locate the wheel (20) adjacent each other and locate the support limbs (18) adjacent the collapsed support arms (12).

Description

COLLAPSIBLE SUPPORT FRAME

The invention relates to a collapsible support frame for carrying a load. Infant pushchairs, golf trolleys and other devices employing support frames for the purposes of carrying loads from one place to another are typically designed so as to be collapsible from an erect configuration to a collapsed configuration so as to facilitate storage when the device is not in use. In the field of infant pushchairs it is particularly desirable for support frames to be readily convertible between erect and collapsed configurations in a quick and easy fashion, with minimum user interaction, so that a user may operate the support frame at the same time as holding, supporting or otherwise controlling a child. According to an aspect of the invention there is provided a collapsible support frame for carrying a load, the support frame in an erect configuration comprising:

a pair of collapsible support arms, each of the support arms being drivingly coupled at or towards a first end to the other support arm for pivotable movement relative thereto and pivotably coupled at or towards a second end to a handle, the support arms being curved to define an open support structure to carry a load;

a pair of support limbs, each support limb carrying a wheel at or towards a first end and being coupled at or towards a second end to a respective support arm for pivotable movement relative thereto, the support limbs in use of the support frame in an erect configuration extending from the respective support arms so as to space the wheels from each other and provide ground engaging support below the open support structure; and

a collapsible linkage assembly extending between the support arms and the support limbs to control pivotable movement of the support limbs relative to the support arms;

the support arms being drivingly coupled such that pivotable movement of one support arm relative to the other support arm drives pivotable movement of the other support arm relative to the one support arm; and

the linkage assembly is collapsible on collapsing of the support arms to pivot the support limbs relative to the support arms so as to locate the wheel adjacent each other and locate the support limbs adjacent the collapsed support arms. The use of collapsible support arms constructed form curved support arm elements helps to ensure that the erect-collapsed volume ratio of the support frame is as large as possible to address users' requirements of compactness when collapsed and the generation of a large footprint when erect.

It will be appreciated that minimising the size of the support frame in its collapsed configuration is advantageous for the purposes of storing and transporting the support frame, particularly when the collapsed support frame is stored in the boot of a vehicle where space is often limited.

It will also be appreciated that maximising the size of the footprint defined by the support frame in its erect configuration is advantageous in terms of maximising the stability of the support frame. This is particularly so in the field of infant pushchairs where it is important that the movement of a child carried in a seat supported on the support arms cannot tip the support frame and potentially injure the child.

Drivingly coupling the support arms, such that pivotable movement of one support arm relative to the other support arm drives pivotable movement of the other support arm relative to the one support arm enhances operation of the support frame.

Preferably, for the purposes of drivingly coupling the support arms, the first end of each support arm is pivotably connected to a coupler, the first end of each support arm being drivingly coupled to the other support arm for pivotable movement relative thereto via the coupler such that pivotable movement of one support arm relative to the coupler drives pivotable movement of the other support arm relative to the coupler.

The use of a coupler allows the pivotable connections of the first ends of the support arms to be spaced apart and thereby reduces the risk of collision between the support arms during collapsing of the support arms.

In such embodiments a toothed member provided on one support arm may be intermeshed with a toothed member provided on the other support arm such that pivotable movement of one support arm relative to the coupler drives pivotable movement of the other support arm relative to the coupler.

Preferably each of the collapsible support arms is constructed from at least two support arm elements, the support arm elements being retained movably captive, one relative to the other, to collapse the support arm on movement of the support frame from its erect configuration to a collapsed configuration, and the support arm elements of each support arm being curved such that collapsing of the support arms pivots the support arms towards each other.

In such embodiments the support arm elements may be retained movably captive, one relative to the other, in a telescoping manner, the support arm elements being slidable, one into another, to collapse the support arm. Such an arrangement provides a neat and attractive support frame that is readily convertible between erect and collapsed configurations in a single-handed operation.

In other embodiments, the support arm elements may be retained movably captive, one relative to the other, in an overlapping manner, the support arm elements being slidable, one past another, to collapse the support arm.

Preferably, so as to maximise the erect-collapsed ratio, the support arm elements of each support arm are equal in length. It is envisaged that in embodiments of the invention each support arm may include two, three or more support arm elements retained movably captive, one relative to another, to collapse the support arm, the greater the number of support arm elements used the greater the erect-collapsed volume ratio of the support frame. So as to facilitate single-handed operation of the support frame in its erect configuration, the handle preferably extends between, and is pivotably connected at each end to, the second ends of the support arms.

Preferably the handle defines a curved grip portion, the grip portion in use of the support frame in an erect configuration curving upwards from the second end of each of the support arms.

The provision of a curved grip portion that, in use of the support frame in an erect configuration, curves upwards from the second end of each of the support arms facilitates use of the support frame by users of different heights without any modification to the support frame. This is because the curved grip portion allows a user to grip the support frame at different positions along the length of the grip portion depending on the handle height required.

In embodiments of the invention the handle may further include a coupling mechanism to drivingly couple pivotable movement of the handle relative to each of the support arms so that pivotable movement of the handle relative to one of the support arms drives pivotable movement of the handle relative to the other of the support arms.

Such coupling reduces the risk of jamming during collapsing of the support frame from its erect configuration to its collapsed configuration, and enhances the operation of the support frame.

In embodiments of the invention, the handle may include at least two handle elements pivotably connected in an end to end configuration, the handle elements extending between the opposite ends of the support arms so as to allow folding of the handle on collapsing of the support arms to further pivot the support arms towards each other.

Such an arrangement allows the size of the support frame to be further minimised in its collapsed configuration.

In such embodiments the handle preferably includes a central handle element pivotably connected between outer handle elements in an end-to-end configuration, the handle elements extending between the second ends of the support arms so as to allow folding of the handle on collapsing of the support arms to further pivot the support arms towards each other.

So as to minimise the risk of jamming and enhance conversion of the support frame between its erect and collapsed configurations, the coupling mechanism preferably drivingly couples pivotable movement of the handle relative to each of the support arms by drivingly coupling the pivotable connections between each end of the central handle element and the respective outer handle element so that pivotable movement of the central handle element relative to one of the outer handle elements drives pivotable movement of the central handle element relative to the other of the outer handle elements.

In such embodiments, the coupling mechanism may include a gear wheel mounted on each of the outer handle elements at the pivotable connection between the outer handle element and the respective end of the central handle element for rotation around the pivotable connection on pivotable movement of the outer handle element relative to the respective end of the central handle element, the gear wheels being drivingly coupled via an intervening gear assembly.

In other embodiments the coupling mechanism may include a gear wheel mounted on each of the outer handle elements at the pivotable connection between the outer handle element and the respective end of the central handle element for rotation around the pivotable connection on pivotable movement of the outer handle element relative to the respective end of the central handle element, the gear wheels being drivingly coupled via a toothed drive belt extending between and about the gear wheels.

In embodiments of the invention, each support limb may be coupled at or towards a second end to a first end of a respective support arm for pivotable movement relative thereto.

Preferably in such embodiments, for the purposes of coupling the support arms and support limbs, the first end of each support arm and the second end of each support limb are pivotably connected to a coupler, the first end of each support arm being drivingly coupled to the other support arm for pivotable movement relative thereto, via the coupler, and the second end of each support limb being coupled to the first end of the respective support arm for pivotable movement relative thereto, via the coupler.

As outlined above, the use of a coupler allows the pivotable connections of the first ends of the support arms to be spaced apart and thereby reduces the risk of collision between the support arms during collapsing of the support arms. It also provides a mechanism whereby the support arms may be drivingly coupled such that pivotable movement of one support arm relative to the coupler drives pivotable movement of the other support arm relative to the coupler, and thereby further enhances operation of the support frame.

The linkage assembly preferably includes a pair of crossed linkage members, each linkage member extending between, and being pivotably connected at each end to, one of the support arms and the support limb coupled thereto, and including a pivotable joint between the respective support arm and support limb so as to allow folding of the linkage member to collapse the linkage assembly on collapsing of the support arms. In such embodiments the crossed linkage members may be interconnected via a linkage coupler and each linkage member may include first and second linkage elements, the first linkage element of each linkage member being pivotably connected at one end to the respective support arm and at its other end to the linkage coupler and the second linkage element of each linkage member being pivotably connected at one end to the respective support limb and at its other end to the linkage coupler.

Preferably the first and second linkage elements of at least one linkage member are drivingly coupled to define a drivingly coupled pair of linkage elements so that pivotable movement of one of the linkage members relative to the linkage coupler drives pivotable movement of the other relative to the linkage coupler.

Such an arrangement enhances the folding operation of the linkage member during collapsing of the support frame, reducing the risk of jamming of the linkage assembly. The or each drivingly coupled pair of linkage elements may include a pair of intermeshed toothed members, one mounted on each of the linkage elements.

To further enhance operation of the support frame and reduce the risk of jamming during conversion of the support frame between its erect and collapsed configurations, at least one of the support arms may be drivingly coupled to the respective support limb so that pivotable movement of one relative to the coupler drives pivotable movement of the other relative to the coupler.

In such embodiments a toothed member provided on the or each drivingly coupled support arm may be intermeshed with a toothed member provided on the respective drivingly coupled support limb.

In particularly preferred embodiments, the collapsible support frame includes one pair of drivingly coupled linkage elements and one support arm drivingly coupled to a respective support limb, the pair of drivingly coupled linkage elements being pivotably connected between the drivingly coupled support arm and support limb. In other embodiments of the invention, each support limb carrying a wheel at or towards one end may be coupled at or towards its other end to a respective support arm, between the first and second ends thereof, for pivotable movement relative to the respective support arm.

Preferably in such embodiments, the linkage assembly includes a pair of crossed linkage members extending between, and being pivotably connected at each end to, one of the support arms and the support limb coupled to the support arm, and each linkage member including first and second linkage elements retained movably captive, one relative to the other, to collapse the linkage member and thereby collapse the linkage assembly on collapsing of the support arms.

The use of linkage members constructed from first and second linkage elements that are retained movably captive, one relative to the other, allows for reduction in the length of the linkage members on collapsing of the linkage assembly. Such an arrangement thereby helps to reduce the size of the support frame in its collapsed configuration whilst providing a linkage member that is sufficiently long in length so as to be extend between the support limbs and uppermost points on the support arms, and thereby maximise the structural support provided by the linkage members in the collapsed configuration of the support frame.

In such embodiments the first and second linkage members may be retained movably captive, one relative to the other, in a telescoping manner, the linkage elements being slidable, one into another, to collapse the linkage member.

In other embodiments, the first and second linkage members may be retained movably captive, one relative to the other, in an overlapping manner, the linkage members being slidable, one past another, to collapse the linkage member. Preferably the crossed linkage members are retained pivotably captive, one relative to the other, via a linkage coupler to allow pivoting movement of the linkage members towards each other on pivoting movement of the support arms towards each other.

The use of a linkage coupler to maintain the relative positions of the crossed linkage members reduces the risk of the crossed linkage members jamming the support frame as a result of moving out of position relative to each other, and thereby enhances conversion of the support frame between its collapsed and erect configurations. In embodiments of the invention, a biaser may be engaged between each support limb and the respective support arm bias the support limbs coupled thereto from the collapsed configuration, in which the wheels are located adjacent each other and the support limbs are located adjacent the support arms, to the erect configuration, in which the support limbs extend from the respective support arms so as to space the wheels from each other and provide ground engaging support below the open support structure.

Such an arrangement encourages movement of the support limbs during conversion of the support frame from its collapsed configuration to its erect configuration and thereby further minimises the amount of user interaction required.

In order to further improve the stability of the support frame in its erect configuration a strut may be provided between each support arm and the support limb coupled thereto, the strut being pivotably connected at or towards one end to the support arm and being pivotably connected at or towards its other end to the support limb and being retained movably captive relative to one of the support arm and the support limb so as to allow movement relative thereto during movement of the support limb between the erect configuration and the collapsed configuration.

So as to provide ground-engaging support below the first ends of the support arms, in use of the support frame in the erect configuration, at least one secondary wheel may be coupled to the first ends of the support arms. Preferred embodiments of the invention will now be described, by way of non-limiting examples, with reference to the accompanying drawings in which:

Figure 1 shows a collapsible support frame according to an embodiment of the invention in an erect configuration;

Figure 2 shows the collapsible support frame of Figure 1 in a collapsed configuration;

Figures 3a and 3b show the first ends of support arms of the collapsible support frame of Figure 1 ;

Figure 4 shows the collapsible support frame of Figure 1 during collapsing movement from the erect configuration to the collapsed configuration;

Figure 5 shows a drivingly coupled pair of linkage elements of the linkage assembly of the collapsible support frame of Figure 1 ; Figure 6 illustrate drivingly coupled support arm and support limb and drivingly coupled linkage members of the collapsible support frame of Figure 1 ;

Figure 7 shows a collapsible support frame according to another embodiment of the invention in an erect configuration;

Figure 8 shows the collapsible support frame of Figure 7 in a collapsed configuration;

Figure 9 shows the collapsible support frame of Figure 7 during collapsing movement from the erect configuration to the collapsed configuration;

Figure 10 shows a linkage coupler of the collapsible support frame of Figure 7; Figures 11a - 11c illustrate operation of a strut during movement of a support limb of the collapsible support frame of Figure 7 from a collapsed configuration to an erect configuration;

Figures 12a and 12b show in schematic form collapsing of the support arms of a collapsible support frame according to a further embodiment of the invention;

Figures 13a and 13b show in schematic form collapsing of the support arms of a collapsible support frame according to another embodiment of the invention;

Figures 14a and 14b show in schematic form collapsing of the support arms of a collapsible support frame according to a further embodiment of the invention;

Figures 15a and 15b show in schematic form collapsing of the support arms of a collapsible support frame according to a yet further embodiment of the invention; and

Figures 16a and 16b show in schematic form collapsing of the support arms of a collapsible support frame according to a yet further embodiment of the invention.

A collapsible support frame 10 according to an embodiment of the invention is shown in Figure 1 in its erect configuration.

The support frame 10 includes a pair of collapsible support arms 12. Each of the support arms 12 is coupled at a first end to the other support arm 12, for pivotable movement relative thereto, via a coupler 14. Each of the support arms 12 is also pivotably coupled at a second end to a handle 16, the handle 16 extending between the second ends of the support arms 12. The support arms 12 are curved to define an open support structure to carry a load there between.

It is envisaged that in other embodiments the coupler 14 may be omitted and the first end of each support arm 12 may be directly coupled to the other support arm 12 for pivotable movement relative thereto. The support frame 10 also includes a pair of support limbs 18. Each support limb 18 carries a wheel 20 at a first end and is coupled at its other end to a respective support arm 12 via the coupler 14 for pivotable movement relative thereto. Each of the support limbs 18 extends from the respective support arm 12, beneath the other of the support arms 12, so as to space the wheels 20 apart from each other and provide ground-engaging support below the open support structure defined by the curved support arms 12. So as to provide structural support to maintain the support arms 12 in position relative to the ground, and to maintain the wheels 20 in a spaced arrangement below the open support structure, the support frame 10 further includes a collapsible linkage assembly 22 extending between the support arms 12 and the support limbs 18. The support arms 12 are each constructed from at least two support arm elements 12a, 12b that are retained movably captive, one relative to the other, in a telescoping manner so that the uppermost support arm elements 12a are slidable into the respective lowermost support arm elements 12b. In other embodiments it is envisaged that the lowermost support arm elements 2a may be slidable into the respective uppermost support arm elements 12a.

In further embodiments it is envisaged that the support arm elements 12a, 12b may be retained movably captive, one relative to the other, in an over-lapping manner so that the support arm elements 12a, 12b are slidable, one past the other.

In yet further embodiments the first and second linkage elements 24a, 24b of each linkage member 24 may be interconnected end to end by means of a hinge connection to allow folding of the linkage member 24.

The uppermost support arm element 12a of each support arm 12 is substantially equal in length to the respective lowermost support arm element 12b.

It is envisaged that in other embodiments the relative lengths of the support arm elements 12a, 12b may vary. It is also envisaged that in other embodiments, each support arm 12 may be constructed from more than two support arm elements 12a, 12b. For example, in other embodiments, each support arm 12 may include three support arm elements retained movably captive, one relative to another.

The handle 16 extending between, and pivotably connected at each end to, the second ends of the support arms 12 includes a central handle element 30 pivotably connected between outer handle elements 32 in an end-to-end configuration.

The central and outer handle elements 30,32 define a curved grip portion, which curves upwards from the second end of each of the support arms 12. The use of a curved grip portion renders the handle 16 effectively height adjustable in that it allows a user to grip the handle 16 at whatever position along the grip portion he or she finds to be a comfortable position relative to the ground, and therefore allows for users of varying heights. The linkage assembly 22 includes a pair of crossed linkage members 24. Each linkage member 24 extends between, and is pivotably connected at each end to, a support arm member 12b of a respective support arm 12 and the support limb 18 coupled thereto. Each linkage member 24 also includes a pivotable joint 26 between the respective support arm 12 and support limb 14.

In the embodiment shown in Figure 1 , the crossed linkage members 24 are interconnected via a linkage coupler 28 and each linkage member 24 includes first and second linkage elements 24a, 24b. The first linkage element 24a of each linkage member 24 is pivotably connected at one end to the respective support arm member 12b and at its other end to the linkage coupler 28. The second linkage element 24b of each linkage member 24 is pivotably connected at one end to the respective support limb 14 and at its other end to the linkage coupler 28.

A pair of secondary wheels 34 is coupled to the first ends of the support arms 12 via the coupler 14. The secondary wheels 34 provide ground-engaging support below the first ends of the support arms 12.

It is envisaged that in other embodiments the secondary wheels 34 may be omitted. In such embodiments the support frame 10 may be tipped backwards on the wheels 20 provided on the support limbs 18 so as to lift the coupler 14 off the ground and allow movement of the support frame 10. In such embodiments a stopper may be provided on the coupler 14 for engagement with the ground to prevent movement of the support frame 10 until such time as the support frame 10 is tipped to lift the stopper off the ground.

The support arms 12 preferably include a latch mechanism to retain the support arm elements 12a, 12b in position relative to each other in a fully extended position.

The handle 16 also preferably includes a latch mechanism to prevent pivotable movement of the central handle element 30 relative to the outer handle elements 32, and thereby prevents folding of the handle 16.

In embodiments of the invention these latch mechanisms may be interconnected so that a user may release the latch mechanisms on the operation of a single button located on the handle 16. The linkage assembly 22 may also include a latch mechanism to retain the linkage members 24 in an erect configuration, extending between the support arms 12 and the support limbs 18. A user may release this latch mechanism by pressing his or her foot against the linkage coupler 28 so as to press the linkage coupler 28 towards the first ends of the support arms 12.

On release of any such latch mechanisms, and any other latch mechanism included to maintain the collapsible support frame in an erect configuration, the support frame 10 may be collapsed from its erect configuration to a collapsed configuration, which is shown in Figure 2.

The support frame 10 is converted to a collapsed configuration by folding the handle 6, collapsing the support arms 12 and collapsing the linkage assembly 22.

The handle 16 is folded by pushing the central handle element 30 forward (Figure 4) relative to the outer handle elements 32 so as to cause pivoting movement of the central handle element 30 relative to the outer handle elements 32. This in turn causes pivoting movement of the outer handle elements 32 relative to the second ends of the support arms 12 and draws the second ends of the support arms 12 towards each other, thereby causing pivotable movement of the support arms 12 towards each other about the pivotable connections between the first ends of the support arms 12 and the coupler 14. A gear wheel (not shown) is mounted on each of the outer handle elements 32 at the pivotable connection between the outer handle element 32 and the central handle element 30 for rotation around the pivotable connection on pivotable movement of the outer handle element 32 relative to the central handle element 30. The gear wheels are drivingly coupled via an intervening gear assembly (not shown) to ensure that pivotable movement of the central handle element 30 relative to one of the outer handle elements 32 will drive pivotable movement of the central handle element 30 relative to the other of the outer handle elements 32. Movement of each of the outer handle elements 32 relative to the central handle element 30 in turn results in pivotable movement of each outer handle element 32 relative to the second end of the respective support arm 12.

In other embodiments it is envisaged that the intervening gear assembly may be replaced by means of a toothed belt extending between and about the gear wheels to transfer drive from the gear wheel mounted at one of the pivotable connections to the gear wheel mounted at the other of the pivotable connections.

Drivingly coupling the pivotable connections between the central handle element 30 and the outer handle elements 32 therefore ensures that the outer handle elements 30 move relative to the respective support arms 12 at the same rate. This is advantageous because it ensures that the continued application of a force to the central handle element 30, to in turn push the uppermost located support arm element 12a into the lowermost arm element 12b, results in collapsing of the support arms 12 at an equal rate to each other. It therefore reduces the risk of jamming that might otherwise occur if one support arm was collapsed at a quicker rate than the other support arm.

The curved nature of the support arm elements 12a, 12b means that on movement of the uppermost support arm elements 12a into the lowermost support arm elements 12b, the support arms 12 are pivoted towards each other about the pivotable connections between the first ends of the support arms 12 and the coupler 14 so as to collapse the support structure.

The first ends of the support arms 12 are drivingly coupled so that movement of one support arm 12 relative to the coupler 14 drives pivotable movement of the other support arm 12 relative to the coupler 14. This ensures that the support arms pivot towards each other at an equal rate and reduces the risk of the support frame 10 jamming during collapsing movement from its erect configuration to its collapsed configuration which might otherwise occur if one support arm 12 was to move at a greater rate relative to the coupler 14 than the other support arm 12.

Referring to Figure 3a the first ends of the support arms 12 are driving coupled by means of the teeth 36 of a toothed member 38 provided on the first end of one of the support arms 12 is intermeshed with the teeth 40 of a toothed member 42 provided on the first end of the other of the support arms 12.

Movement of the lowermost support arm elements 12b towards each other and into, on folding of the handle 16 and collapsing of the support arms 12, forces the linkage members 24a pivotably connected thereto to pivot relative to the lowermost support arm elements 12b. This in turn causes pivotable movement of the uppermost linkage members 24a relative to the linkage coupler 28 and continued movement thereof causes pivoting movement of the linkage coupler 28 relative to the lowermost linkage members 24b, causing the linkage members 24 to fold and collapse, as shown in Figure 4.

Collapsing of the linkage members 24 causes pivoting movement of the support limbs 18 relative to the coupler 14 so as to pivot the support limbs 18 towards each other and locate the wheels 20 adjacent each other.

To improve driving movement of the support limbs 18 relative to the coupler 14, and enhance the collapsing and erecting operations, one of the support limbs 18 is drivingly coupled to its associated support arm 12 so that pivoting movement of the associated support arm 12 relative to the coupler 14 drives pivoting movement of the support limb 18 relative to the coupler 14.

Driving pivoting movement of the support limb 18 in this manner assists in collapsing of the linkage member 24 connected between the coupled support arm 12 and support limb 18, as illustrated in Figure 6. It will be appreciated that it will also assist during conversion of the support frame 10 from its collapsed configuration to its erect configuration.

Referring to Figure 3b the first end of one of the support arms 12 is driving coupled by means of the teeth 44 of a toothed member 46 provided on its first end intermeshed with the teeth 48 of a toothed member 50 provided on the end of the support limb 18 coupled thereto. To further improve collapsing movement of the linkage assembly 22, and enhance the collapsing and erecting operations, the first and second linkage elements 24a, 24b of the linkage member 24 connected between the drivingly coupled support arm 12 and support limb 18 are drivingly coupled so that pivoting movement of one of the linkage elements relative to the linkage coupler 28 drives pivoting movement of the other linkage element relative to the linkage coupler 28.

Driving pivoting movement of the linkage elements 24a,24b in this manner assists in collapsing of the linkage assembly 22. It will be appreciated that it will also assist during conversion of the support frame 10 from its collapsed configuration to its erect configuration.

Referring to Figure 5, one of the linkage elements 24a is drivingly coupled to the other of the linkage elements 24b by means of teeth 23 on a toothed member 25 mounted on the linkage element 24a intermeshed with teeth 27 of a toothed member 29 provided on the other linkage element 24b.

The interconnection between the linkage members 24 provided by the linkage coupler 28 means that it is not necessary to drivingly couple the linkage elements 24a,24b of the other linkage member 24, nor is it necessary to drivingly couple the other support limb 18 to the support arm 12 with which it is coupled. In other embodiments however the linkage elements 24a, 24b of the other linkage member 24 may be drivingly coupled. Similarly the other support limb 18 may be drivingly coupled to the support arm 12 with which it is coupled.

While the operation described above concentrates on collapsing of the collapsible support frame 10, it will be appreciated that conversion of the support frame 10 from its collapsed configuration to its erect configuration will work in a corresponding manner in that a user may pull on the handle 16, which in turn will pull the support arms 12 so as to extend the support arms 12, causing relative pivotable movement of the support arms 12 relative to the coupler 14 and the resultant movement of the linkage assembly 22 and the support limbs 18 by virtue of the coupling of these components outlined above. It will therefore also be appreciated that the ability to start and control conversion of the collapsible support frame 10 between its erect and collapsed configuration allow single- handed operation of the collapsible support frame 10. A collapsible support frame 110 according to another embodiment of the invention is shown in Figure 7 in its erect configuration.

The support frame 110 includes a pair of collapsible support arms 112. Each of 'the support arms 112 is coupled at a first end to the other support arm 112, for pivotable movement relative thereto, via a coupler 114. Each of the support arms 112 is also pivotably coupled to a second end to a handle 116, the handle 116 extending between the second ends of the support arms 112. The support arms 112 are curved to define an open support structure to carry a load there between.

It is envisaged that in other embodiments the coupler 114 may be omitted and the first end of each support arm 112 may be directly coupled to the other support arm 112 for pivotable movement relative thereto. The support frame 110 also includes a pair of support limbs 18. Each support limb 118 carries a wheel 120 at a first end and is pivotably coupled at its other end to a respective support arm 112 via a joint 113 located between the first and second ends of the support arm 112 for pivotable movement relative to the support arm 112. Each of the support limbs 118 extends from the respective support arm 12 so as to space the wheels 120 apart from each other and provide ground-engaging support below the open support structure defined by the curved support arms 12.

So as to provide structural support to maintain the support arms 112 in position relative to the ground, and to maintain the wheels 120 in a spaced arrangement below the open support structure, the support frame 110 further includes a collapsible linkage assembly 122 extending between the support arms 112 and the support limbs 118.

The support arms 112 are each constructed from at least two support arm elements 112a, 112b that are retained movably captive one relative to the other, in a telescoping manner so that the uppermost support arm elements 112a are slidable into the respective lowermost support arm elements 112b.

In other embodiments, it is envisaged that the lowermost support arm elements 112b may be slidable into the respective uppermost support arm elements 112a. In further embodiments it is envisaged that the support arm elements 112a, 112b may be retained movably captive, one relative to the other, in an over-lapping manner so that the support arm elements 112a, 112b are slidable, one past the other. In yet further embodiments the first and second linkage elements 124a, 124b of each linkage member 124 may be interconnected end to end by means of a hinge connection to allow folding of the linkage member 124.

The uppermost support arm element 112a of each support arm 112 is substantially equal in length to the respective lowermost support arm element 112b.

It is envisaged that in other embodiments the relative lengths of the support arm elements 112a, 1 2b may be constructed from more than two support arm elements 112a,112b. For example, in other embodiments, each support arm 112 may include three support arm elements retained movably captive, one relative to another.

The handle 116 extending between, and pivotably connected at each end to, the second ends of the support arms 112 includes a central handle element 130 pivotably connected between outer handle elements 132 in an end-to-end configuration.

The central and outer handle elements 130,132 define a curved grip portion, which curves upwards from the second end of each of the support arms 112. The use of a curved grip portion renders the handle 116 effectively height adjustable in that.it allows a user to grip the handle 116 at whatever position along the grip portion he or she finds to be a comfortable position relative to the ground, and therefore allows for users of varying heights.

The linkage assembly 122 includes a pair of crossed linkage members 124. Each linkage member 124 extends between, and is pivotably connected at each end to, a support arm member 112a of a respective support arm 112 and the support limb 118 coupled thereto.

More specifically, each linkage member 124 extends between, and is pivotably connected at each end to, the second end of the respective support arm 112 and the wheel 120 provided on the respective support limb 118. This arrangement maximises the structural support provided by the linkage assembly 122 and minimises the amount of turning moments about joints 113 that might otherwise be applied to the support arms 112 as a result of downward forces applied to the handle 116 during use. In the embodiment shown in Figure 7, each of the linkage members 124 includes first and second linkage elements 124a, 124b retained movably captive, one relative to the other, in a telescoping manner so that the lowermost linkage elements 124b are slidable into the respective uppermost linkage elements 124a.

In other embodiments, it is envisaged that the uppermost linkage elements 124a may be slidable into the respective lowermost linkage elements 124b. In further embodiments, it is envisaged that the linkage elements 124a,124b may be retained movably captive, one relative to the other, in an over-lapping manner so that the linkage elements 124a, 124b are slidable, one past the other.

The uppermost linkage elements 124a of the linkage members 124 are retained movably captive, one relative to the other, via a linkage coupler 128 to allow pivoting movement of the linkage members 124 relative to each other about a pivotable joint 126.

A biaser (not shown) is provided in the joint 113 connecting each support limb 118 to the respective support arm 112. The biaser includes a spring engaged between the respective support limb 118 and support arm 112 so as to bias the support limb 118 away from the support limb 112, into its erect configuration.

Referring to Figures 11a - 11c, a strut 134 is provided between each support limb 118 and the support arm 112 to which it is coupled.

The strut 134 is pivotably coupled at one end to a sliding joint 136 mounted on the lowermost support arm element 112b of the support arm 112, the joint 136 being slidable along the length of the support arm element 112b. The strut 134 is pivotably coupled at its other end to the support limb 118 via a collar 138 provided on the support limb 118 for sliding movement along the length thereof.

In the erect configuration of the collapsible support frame (Figure 11c), the strut 134 extends between the support limb 118 and the support arm 112 so as to hold the support limb 118 in position relative to the support arm 112. During pivotable movement of the support limb 118 relative to the support arm 112, either from or towards the collapsed configuration, the sliding joint 136 and collar 138 facilitate movement of the strut 134 relative to the support arm 112 and the support limb 118 so as to allow relative movement between the support arm 112 and the support limb 118, as shown in Figures 11a - 11c.

A pair of secondary wheels 134 is coupled to the first ends of the support arms 112 via the coupler 114. The secondary wheels 134 provide ground-engaging support below the first ends of the support arms 1 2.

It is envisaged that in other embodiments the secondary wheels 134 may be omitted. In such embodiments the support frame 110 may be tipped backwards on the wheels 120 provided on the support limbs 118 so as to lift the coupler 114 off the ground and allow movement of the support frame 110. In such embodiments a stopper may be provided on the coupler 114 for engagement with the ground to prevent movement of the support frame 110 until such time as the support frame 110 is tipped to lift the stopper off the ground.

The support arms 112 preferably include a latch mechanism to retain the support arm elements 112a, 112b in position relative to each other in a fully extended position.

The handle 116 also preferably includes a latch mechanism to prevent pivotable movement of the central handle element 130 relative to the outer handle elements 132, and thereby prevents folding of the handle 116.

In embodiments of the invention these latch mechanisms may be interconnected so that a user may release the latch mechanisms on the operation of a single button located on the handle 1 6. The linkage assembly 122 may also include a latch mechanism to retain the linkage members 24 in an erect configuration, extending between the support arms 112 and the support limbs 118. The latch mechanism may be provided on the linkage coupler 128 and may include a spring biased pin that automatically engages apertures provided in the uppermost linkage elements 124a of the linkage members 124, which only align and allow automatic engagement with the spring biased pin there through when the linkage member 124 are located in the erect configuration. A user may release this latch mechanism by pulling the pin out of the holes and thereby allowing pivotable movement of the uppermost linkage elements 124a, and therefore the linkage members 124, relative to each other. It will be appreciated that engagement of the pin in such apertures will also prevent telescoping movement of the uppermost and lowermost linkage elements 124a, 124b relative to each other since the engagement of the pin through the uppermost linkage elements 124a will prevent relative movement of the lowermost linkage elements 124b into the respective uppermost linkage elements 24a.

On release of any such latch mechanisms, and any other latch mechanism included to maintain the collapsible support frame in an erect configuration, the support frame 10 may be collapsed from its erect configuration to a collapsed configuration, which is shown in Figure 8.

The support frame 110 is converted to a collapsed configuration by folding the handle 116, collapsing the support arms 112 and collapsing the linkage assembly 122.

The handle 116 is folded by pushing the central handle element 130 forward relative to the outer handle elements 132 so as to cause pivoting movement of the central handle element 130 relative to the outer handle elements 132. This in turn causes pivoting movement of the outer handle elements 132 relative to the second ends of the support arms 112 and draws the second ends of the support arms 112 towards each other, thereby causing pivotable movement of the support arms 112 towards each other about the pivotable connections between the first ends of the support arms 112 and the coupler 114. A gear wheel (not shown) is mounted on each of the outer handle elements 132 at the pivotable connection between the outer handle element 132 and the central handle element 130 for rotation around the pivotable connection on pivotable movement of the outer handle element 132 relative to the central handle element 130. The gear wheels are drivingly coupled via an intervening gear assembly (not shown) to ensure that pivotable movement of the central handle element 130 relative to one of the outer handle elements 132 will drive pivotable movement of the central handle element 130 relative to the other of the outer handle elements 132. Movement of each of the outer handle elements 132 relative to the central handle element 130 in turn results in pivotable movement of each outer handle element 132 relative to the second end of the respective support arm 112. In other embodiments it is envisaged that the intervening gear assembly may be replaced by means of a toothed belt extending between and about the gear wheels to transfer drive from the gear wheel mounted at one of the pivotable connections to the gear wheel mounted at the other of the pivotable connections.

Drivingly coupling the pivotable connections between the central handle element 130 and the outer handle elements 132 therefore ensures that the outer handle elements 130 move relative to the respective support arms 112 at the same rate. This is advantageous because it ensures that the continued application of a force to the central handle element 130, to in turn push the uppermost located support arm element 112a into the lowermost arm element 112b, results in collapsing of the support arms 112 at an equal rate to each other. It therefore reduces the risk of jamming that might otherwise occur if one support arm was collapsed at a quicker rate than the other support arm. The curved nature of the support arm elements 112a, 112b means that on movement of the uppermost support arm elements 112a into the lowermost support arm elements 112b, the support arms 112 are pivoted towards each other about the pivotable connections between the first ends of the support arms 112 and the coupler 114 so as to collapse the support structure.

The first ends of the support arms 112 are drivingly coupled so that movement of one support arm 112 relative to the coupler 114 drives pivotable movement of the other support arm 112 relative to the coupler 114. This ensures that the support arms pivot towards each other at an equal rate and reduces the risk of the support frame 110 jamming during collapsing movement from its erect configuration to its collapsed configuration which might otherwise occur if one support arm 112 was to move at a greater rate relative to the coupler 114 than the other support arm 112.

The first ends of the support arms 112 are driving coupled by means of the teeth (not shown) of a toothed member (not shown) provided on the first end of one of the support arms 112 is intermeshed with the teeth (not shown) of a toothed member (not shown) provided on the first end of the other of the support arms 112.

Movement of the uppermost support arm elements 112a towards each other and into the respective lowermost support arm elements 112b, on folding of the handle 116 and collapsing of the support arms 1 12, forces the uppermost linkage elements 124a pivotably connected thereto to pivot relative to the support arm 1 2. This in turn causes pivotable movement of the uppermost linkage members 124a relative to each other about the pivotable joint 126 of the linkage coupler 128.

It also forces the uppermost linkage elements 124a of the linkage members 124 to move relative to the lowermost linkage elements 124b so that the lowermost linkage elements 124b slide into the uppermost linkage elements 124a, as shown in Figure 9.

Collapsing of the linkage members 124 causes pivoting movement of each of the support limbs 118 relative to the support arm 112 to which it is coupled so as to pivot the support limbs 118 towards each other and locate the wheels 120 adjacent each other.

The position of the joint 113 coupling each support limb 118 to the respective support arm 112 means that on pivoting movement of the support limb 118 relative to the support arm 112, the wheel 120 mounted thereon is moved into a position where it is located the secondary wheels 134. This can provide advantages during storage of the support frame in its collapsed configuration stood up against a wall in that it allows all wheels to be located on or towards the ground and ensures that wheels 120,134 do not rest against the wall, the first ends of the support arms 112 instead resting against the wall. It therefore reduces the risk of dirty wheels marking the wall, which might otherwise occur if the collapsed storage frame is position so that the wheels 120 rest against the wall.

While the operation described above concentrates on collapsing of the collapsible support frame 110, it will be appreciated that conversion of the support frame 110 from its collapsed configuration to its erect configuration will work in a corresponding manner in that a user may pull on the handle 116, which in turn will pull the support arms 112 so as to extend the support arms 112, causing relative pivotable movement of the support arms 112 relative to the coupler 114 and the resultant movement of the linkage assembly 122 and the support limbs 118 by virtue of the coupling of these components outlined above. It will be appreciated that the ability to start and control conversion of the collapsible support frame 110 between its erect and collapsed configuration allow single- handed operation of the collapsible support frame 110.

In each of the embodiments shown in Figures 1 and 7, collapsing of the support arms 12,112 reduces their overall length within the support frame 10,110 by approximately half. This reduction in size may be increased in other embodiments by increasing the number of support arm elements used to construct the support arms 12,112. For example, constructing each support arm 12,112 from three support arm elements will lead to a reduction of two thirds of the overall length of the support arms 12,112 on collapsing of the support arms 12,112.

Altering the structure of the handle 16,116 in each of the embodiments shown in Figures 1 and 7 will also affect the extent to which the support arms 12,112 may pivot towards each other during collapsing of the support frame 10,110, as illustrated in Figures 12a and 12b, Figures 13a and 13b, Figures 14a and 14b, Figures 15a and 15b and Figures 16a and 16b . For convenience, the following description of Figures 12a and 12b, Figures 13a and 13b, Figures 14a and 14b, Figures 15a and 15b and Figures 16a and 16b will make use of the reference numerals used in Figure 1. It will be appreciated however that it is equally applicable to the collapsible support frame 110 shown in Figure 7. Figures 12a and 12b illustrate collapsing of the support arms 12 of a collapsible support frame 10 according to a similar embodiment of the invention to that shown in Figure 1 , Figure 12a showing the support arms 12 and the handle 16 in the erect configuration of the support frame 10 and Figure 12b showing the support arms 12 and the handle 16 in the collapsed configuration of the support frame 10. The support arms 12 shown in this embodiment differ from the support arms 12 of the support frame 10 shown in Figure 1 only in that the support arm elements 12a, 12b of each support arm 12 are retained movably captive, one relative to the other, in an overlapping manner as opposed to a telescoping manner. Figures 13a and 13b illustrate collapsing of the support arms 12 of a collapsible support frame 10 according to another embodiment of the invention in which the handle 16 is constructed from two handle elements 16a, 16b pivotably coupled to each other in an end-to-end configuration between the second ends of the support arms 12. Figures 14a and 14b illustrate collapsing of the support arms 12 of a collapsible support frame 10 according to a further embodiment of the invention in which the handle 16 is constructed from a single handle element pivotably coupled at each end between the second ends of the support arms 12. It will be appreciated from the figures that the absence of an additional handle element in the handle 16 of the support frame 10 shown in Figures 14a and 14b, that would otherwise allow folding of the handle 16 during collapsing of the support arms 12, prevents pivoting movement of the support arms 12 towards each other to the same extent as shown in Figures 12b and 13b.

In embodiments in which the handle 16 includes a single handle element, the overall size of the collapsed support frame may be reduced by directly coupling the first ends of the support arms, as shown in Figures 15a and 15b.

The overall size of the collapsed support frame may be reduced further by providing a handle 16 that pivotably couples the second ends of the support arms 12 directly to each other, as shown in Figures 16a and 16b.

It will be appreciated that to ensure smooth conversion of the support arms 12 between their erect and collapsed configurations, the curvature of each of the support arm elements 12a, 12b is equal.

Claims

1. A collapsible support frame for carrying a load, the support frame in an erect configuration comprising:

a pair of support limbs, each support limb carrying a wheel at or towards a first end and being coupled at or towards a second end to a respective support arm for pivotal movement relative thereto, the support limbs in use of the support frame in an erect configuration extending from the respective support arms so as to space the wheels from each other and provide ground engaging support below the open support structure; and

a collapsible linkage assembly extending between the support arms and the support limbs to control pivoting movement of the support limbs relative to the support arms;

the linkage assembly is collapsible on collapsing of the support arms to pivot the support limbs relative to the support arms so as to locate the wheel adjacent each other and locate the support limbs adjacent the collapsed support arms.

2. A collapsible support frame according to Claim 1 wherein the first end of each support arm is pivotably connected to a coupler, the first end of each support arm being drivingly coupled to the other support arm for pivotable movement relative thereto via the coupler such that pivotable movement of one support arm relative to the coupler drives pivotable movement of the other support arm relative to the coupler.

3. A collapsible support frame according to Claim 2 wherein a toothed member provided on one support arm is intermeshed with a toothed member provided on the other support arm such that pivotable movement of one support arm relative to the coupler drives pivotable movement of the other support arm relative to the coupler.

4. A collapsible support frame according to any of Claims 1 to 3 wherein each of the collapsible support arms is constructed from at least two support arm elements, the support arm elements being retained movably captive, one relative to the other, to collapse the support arm on movement of the support frame from its erect configuration to a collapsed configuration, and the support arm elements of each support arm being curved such that collapsing of the support arms pivots the support arms towards each other.

5. A collapsible support frame according to Claim 4 wherein the support arm elements are retained movably captive, one relative to the other, in a telescoping manner, the support arm elements being slidable, one into another, to collapse the support arm.

6. A collapsible support frame according to Claim 4 wherein the support arm elements are retained movably captive, one relative to the other, in an overlapping manner, the support arm elements being slidable, one past another, to collapse the support arm.

7. A collapsible support frame according to any of Claims 4 to 6 wherein the support arm elements of each support arm are equal in length.

8. A collapsible support frame according to any preceding claim wherein the handle extends between, and is pivotably connected at each end to, the second ends of the support arms.

9. A collapsible support frame according to Claim 8 wherein the handle defines a curved grip portion, the grip portion in use of the support frame in an erect configuration curving upwards from the second end of each of the support arms.

10. A collapsible support frame according to Claims 8 and 9 wherein the handle further includes a coupling mechanism to drivingly couple pivotable movement of the handle relative to each of the support arms so that pivotable movement of the handle relative to one of the support arms drives pivotable movement of the handle relative to the other of the support arms.

11. A collapsible support frame according to any of Claims 8 to 10 wherein the handle includes at least two handle elements pivotably connected in an end to end configuration, the handle elements extending between the second ends of the support arms so as to allow folding of the handle on collapsing of the support arms to further pivot the support arms towards each other.

12. A collapsible support frame according to Claims 8 to 11 wherein the handle includes a central handle element pivotably connected between outer handle elements in an end to end configuration, the handle elements extending between the second ends of the support arms so as to allow folding of the handle on collapsing of the support arms to further pivot the support arms towards each other.

13. A collapsible support frame according to Claims 10 to 12 wherein pivotable movement of the central handle element relative to each of the outer handle elements results in pivotable movement of the outer handle elements relative to the respective support arms and the coupling mechanism drivingly couples pivotable movement of the handle relative to each of the support arms by drivingly coupling the pivotable connections between each end of the central handle element and the respective outer handle element so that pivotable movement of the central handle element relative to one of the outer handle elements drives pivotable movement of the central handle element relative to the other of the outer handle elements.

14. A collapsible support frame according to Claim 13 wherein the coupling mechanism includes a gear wheel mounted on each of the outer handle elements at the pivotable connection between the outer handle element and the respective end of the central handle element for rotation around the pivotable connection on pivotable movement of the outer handle element relative to the respective end of the central handle element, the gear wheels being drivingly coupled via an intervening gear assembly.

15. A collapsible support frame according to Claim 13 wherein the coupling mechanism includes a gear wheel mounted on each of the outer handle elements at the pivotable connection between the outer handle element and the respective end of the central handle element for rotation around the pivotable connection on pivotable movement of the outer handle element relative to the respective end of the central handle element, the gear wheels being drivingly coupled via a toothed drive belt extending between and about the gear wheels.

16. A collapsible support frame according to any preceding claim wherein each support limb is coupled at or towards a second end to a first end of a respective support arm for pivotable movement relative thereto.

17. A collapsible support frame according to Claim 2 or Claim 3 and Claim 16 wherein the second end of each support limb is pivotably connected to the coupler, and the second end of each support limb is coupled to the first end of the respective support arm for pivotable movement relative thereto via the coupler.

18. A collapsible support frame according to Claim 16 or Claim 17 wherein the linkage assembly includes a pair of crossed linkage members, each linkage member extending between, and being pivotably connected at each end to, one of the support arms and the support limb coupled thereto and including a pivotable joint between the respective support arm and support limb so as to allow folding of the linkage member to collapse the linkage assembly on collapsing of the support arms.

19. A collapsible support frame according to Claim 18 wherein the crossed linkage members are interconnected via a linkage coupler and each linkage member includes first and second linkage elements, the first linkage element of each linkage member being pivotably connected at one end to the respective support arm and at its other end to the linkage coupler and the second linkage element of each linkage member being pivotably connected at one end to the respective support limb and at its other end to the linkage coupler.

20. A collapsible support frame according to Claim 19 wherein the first and second linkage elements of at least one linkage member are drivingly coupled to define a drivingly coupled pair of linkage elements so that pivotable movement of one relative to the linkage coupler drives pivotable movement of the other relative to the linkage coupler.

21. A collapsible support frame according to Claim 20 wherein the or each drivingly coupled pair of linkage elements includes a pair of intermeshed toothed members, one mounted on each of the linkage elements.

22. A collapsible support frame according to any of Claims 17 to 21 wherein at least one of the support arms is drivingly coupled to the respective support limb so that pivotable movement of one relative to the coupler drives pivotable movement of the other relative to the coupler.

23. A collapsible support frame according to Claim 22 wherein a toothed member provided on the or each drivingly coupled support arm is intermeshed with a toothed member provided on the respective drivingly coupled support limb.

24. A collapsible support frame according to Claim 20 or Claim 21 and Claim 22 or Claim 23 including one pair of drivingly coupled linkage elements and one support arm drivingly coupled to a respective support limb, the pair of drivingly coupled linkage elements being pivotably connected between the drivingly coupled support arm and support limb.

25. A collapsible support frame according to any of Claims 1 to 15 wherein each support limb carrying a wheel at or towards one end is coupled at or towards its other end to a respective support arm, between the first and second ends thereof, for pivotable movement relative to the respective support arm.

26. A collapsible support frame according to Claim 25 wherein the linkage assembly includes a pair of crossed linkage members extending between, and being pivotably connected at each end to, one of the support arms and the support limb coupled to the other support arm, and each linkage member including first and second linkage elements retained movably captive, one relative to the other, to collapse the linkage member and thereby collapse the linkage assembly on collapsing of the support arms.

27. A collapsible support frame according to Claim 26 wherein the first and second linkage elements of each linkage member are retained movably captive, one relative to the other, in a telescoping manner, the linkage elements being slidable, one into the another, to collapse the linkage member.

28. A collapsible support frame according to Claim 26 wherein the first and second linkage elements of each linkage member are retained movably captive, one relative to the other, in an overlapping manner, the linkage members being slidable, one past another, to collapse the linkage member.

29. A collapsible support frame according to any of Claims 26 to 28 wherein the crossed linkage members are retained pivotably captive, one relative to the other, via a linkage coupler to allow pivoting movement of the linkage members towards each other on pivoting movement of the support arms towards each other.

30. A collapsible support frame according to any of Claims 25 to 29 further including a biaser engaged between each support limb and the respective support arm to bias the support limbs coupled thereto from the collapsed configuration in which the wheels are located adjacent each other and the support limbs are located adjacent the support arms to the erect configuration in which the support limbs extend from the respective support arms so as to space the wheels from each other and provide ground engaging support below the open support structure.

31. A collapsible support frame according to any of Claims 25 to 30 wherein a strut is provided between each support arm and the support limb coupled thereto, the strut being pivotably connected at or towards one end to the support arm and pivotably connected at or towards its other end to the support limb and being retained movably captive relative to one of the support arm and the support limb so as to allow movement relative thereto during movement of the support limb between the erect configuration and the collapsed configuration.

32. A collapsible support frame according to any preceding claims further including at least one secondary wheel coupled to the first ends of the support arms to provide, in use of the support frame in its erect configuration, ground engaging support below the first ends of the support arms.