GB2380982A

GB2380982A - A steerable wind-powered vehicle chassis

Info

Publication number: GB2380982A
Application number: GB0125031A
Authority: GB
Inventors: Kieron Bradley; Matthew Sansum
Original assignee: Individual
Current assignee: Individual
Priority date: 2001-10-18
Filing date: 2001-10-18
Publication date: 2003-04-23
Also published as: GB0125031D0

Abstract

A steerable wind-powered vehicle chassis 10 comprises a support frame 16 and an axle arrangement 12 supported by the support frame 16 and on which a wheel 22 is rotatably mounted. The axle arrangement 12 includes an axle element 20, means between the axle element 20 and the wheel 22 for selectively adjusting the camber of the wheel 22, and means for selectively adjusting the toe of the wheel 22. The axle arrangement may alternatively include means for preventing or inhibiting the chassis being pulled off-line and/or unintentionally destabilised when in use. A method of preventing or inhibiting a steerable wind-powered vehicle being pulled off-line and/or unintentionally destabilised and a method of configuring a steerable wind-powered vehicle for use as a racing chassis and as a freestyle chassis are also provided.

Description

Improvements in or relating to a steerable wind-powered vehicle chassis This invention relates to a steerable wind-powered vehicle chassis, in particular, a para-kart chassis, a method of preventing or inhibiting a steerable windpowered vehicle using such a chassis being pulled off-line and/or unintentionally destabilised, and to a method of configuring a steerable wind-powered vehicle having such a chassis for use as a racing chassis and as a freestyle chassis.

Steerable wind-powered vehicle chassises are known. One particular kind of this type of wheeled chassis is that of a para-kart or para-kite. A para-kart or parakite utilises a para-sail operated by the rider of the chassis to be propelled along the ground.

However, a problem becomes apparent when a using such a para-kart or-kite in that, if the prevailing wind is not directly with the user, i. e. is cross-wind prevailing from one side or the other, then the para-kart or-kite tends to be pulled off-line. This particularly occurs when the para-sail catches a gust and the user either has insufficient time to steer into the wind or insufficient freedom of steering, such as on a racing chassis, to compensate for the gust. In certain cases, the gust may be sufficient to destabilise and overturn the para-kart or-kite.

A further disadvantage is apparent in that, without pivotable suspension, the para-kite or-kart is subjected to numerous shocks when in use, which are easily transmitted through the entire chassis leading to weakening and breakage of high

load-bearing points.

Furthermore, known suspension, being of the wishbone type, has limited the para-kart or-kite to which it has been applied to racing only, due to the fact that in order to accommodate such suspension, a relatively long rear axle is required.

In addition, in order to compete in racing as well as freestyle competitions, two separate chassises are presently required, since the set-up for each type is different. Wheel base length, ride-height, rear wheel positioning and alignment, rear axle positioning, front fork rake angle, and stirrup height and orientation all have to be selectively set for the individual and for the type of event.

Another problem occurs with the frame support in which the user sits. This is typically a single section of frame contoured to accept the users torso. The user is thus provided with nothing to brace the legs, or part thereof, during use.

Furthermore, the neck portion through which the frame support joins the front axle arrangement is subjected to severe loads and commonly fails.

The present invention seeks to overcome these problems.

According to a first aspect of the present invention, there is provided a steerable wind-powered vehicle chassis for use with a para-kart, the chassis comprising a support frame and an axle arrangement supported by the support frame

and on which a wheel is rotatably mounted, the axle arrangement including an axle element, means between the axle element and the wheel for selectively adjusting the camber of the wheel, and means for selectively adjusting the toe of the wheel.

A'para-kart'is, in the art, also commonly known as a'para-kite', and the use of either term throughout is intended to be construed as including the other.

Preferable and/or optional features of the first aspect of the present invention are set forth in claims 2 to 35, inclusive.

According to a second aspect of the present invention, there is provided a steerable wind-powered vehicle chassis for use with a para-kart, the chassis comprising a support frame and a rear axle arrangement supported by the support frame and on which a wheel is rotatably mounted, the rear axle arrangement including means for preventing or inhibiting the chassis being pulled off-line and/or unintentionally destabilised when in use.

According to a third aspect of the present invention, there is provided a method of preventing or inhibiting a steerable wind-powered vehicle, using a chassis in accordance with any one of claims 4 to 35, being pulled off-line and/or unintentionally destabilised, the method comprising the steps of: a) determining the strength and direction of the prevailing wind;

b) setting the camber of the or each rear wheel using the camber adjustment means based on the strength and direction of the prevailing wind; and c) setting the toe of the rear wheels using the toe adjustment means based on the strength and direction of the prevailing wind, so that when a crosswise or substantially crosswise wind force, which tends to want to pull or drag the vehicle off-line and/or destabilise it, acts directly and/or indirectly on the chassis, a downward movement of the support frame relative to the or each wheel results in a variation of the toe of the or each rear wheel in a toe-in direction, thereby tending to counter-act the force wind force.

Preferably, the method further comprises a step subsequent to step (a) of setting the ride height using the ride height adjustment means and/or the rake angle adjustment means based on the strength and direction of the prevailing wind.

I According to a fourth aspect of the present invention, there is provided a method of configuring a steerable wind-powered vehicle, having a chassis in accordance with any one of claims 4 to 35, for use as a racing chassis and as a freestyle chassis, the method comprising the steps of: a) determining which chassis set-up is required;

b) determining the strength and direction of the prevailing wind; c) setting the camber of the or each rear wheel using the camber adjustment means based on the chassis set-up required and the strength and direction of the prevailing wind; and d) setting the toe of the or each rear wheel using the toe adjustment means based on the chassis set-up required and the strength and direction of the prevailing wind, so that racing characteristics, which require a stable chassis able to counter-act or substantially counter-act a crosswise or substantially crosswise wind force directly and/or indirectly applied to the chassis which tends to want to pull or drag the vehicle off-line and/or destabilise it, can be set, or so that freestyle characteristics, which require a less-stable chassis, can be set, or so that a combination of characteristics can be set.

Preferable and/or optional features of the fourth aspect of the present invention are set forth in claims 40 to 42, inclusive.

According to a fifth aspect of the present invention, there is provided a steerable wind-powered vehicle chassis for use with a para-kart, the chassis comprising a support frame, an axle arrangement supported by the support frame and on which a wheel is rotatably mounted, and a suspension linkage interconnecting the

support frame and the axle arrangement, the suspension linkage including a trailingarm member which is supported for pivotable movement at or adjacent to one end by the support frame and which is fixed to the axle arrangement at or adjacent to its other end.

Preferable and/or optional features of the fifth aspect of the present invention are set forth in claims 44 to 51, inclusive.

According to a sixth aspect of the present invention, there is provided a steerable wind-powered vehicle chassis for use with a para-kart, the chassis comprising a support frame, a rear axle arrangement which is supported by the support frame and which rotatably supports a wheel, and a front axle arrangement which is supported by the support frame through a neck portion and which rotatably supports another wheel, the support frame including a first frame section and a second frame section which engage the neck portion so that the load is spread therebetween.

Preferable and/or optional features of the sixth aspect of the present invention are set forth in claims 53 to 57, inclusive.

According to a seventh aspect of the present invention, there is provided a steerable wind-powered vehicle chassis for use with a para-kart, the chassis comprising a support frame, a rear axle arrangement which is supported by the support frame and which rotatably supports a wheel, and a front axle arrangement

which is supported by the support frame through a neck portion and which rotatably supports another wheel, the neck portion being slidably adjustable to extend and reduce the wheel base of the chassis.

Preferable and/or optional features of the seventh aspect of the present invention are set forth in claims 59 to 61.

According to an eighth aspect of the present invention, there is provided a steerable wind-powered vehicle chassis for use with a para-kart, the chassis comprising a support frame, a rear axle arrangement which is supported by the support frame and which rotatably supports a wheel, and a front axle arrangement which is supported by the support frame through a neck portion and which rotatably supports another wheel, the front axle arrangement including a steerable front fork element and means interposed between the front fork element and the neck portion for adjusting the rake angle of the front forks.

Preferable and/or optional features of the eighth aspect of the present invention are set forth in claims 63 to 67, inclusive.

According to a ninth aspect of the present invention, there is provided a steerable wind-powered vehicle chassis for use with a para-kart, the chassis comprising a support frame, a rear axle arrangement which is supported by the support frame and which rotatably supports a wheel, and a front axle arrangement which is pivotably supported by the support frame for steering and which rotatably

supports another wheel, the front axle arrangement including a front fork element and stirrups releasably attached to the front fork elements, the stirrups being fixable at different positions along the longitudinal extent of the front fork element to accommodate users of different heights.

Preferable and/or optional features of the ninth aspect of the present invention are set forth in claim 69 and/or claim 70.

According to a tenth aspect of the present invention, there is provided a steerable wind-powered vehicle chassis for use with a para-kart, the chassis comprising a support frame and an axle arrangement supported by the support frame, the axle arrangement including an axle element, on each end of which a wheel is rotatably mounted, and means by which the axle element can be axially displaced so that the said wheels are asymmetrically positioned relative to the support frame.

Preferable and/or optional features of the tenth aspect of the present invention are set forth in claims 72 to 74, inclusive.

The present invention will now be described, by way of example only, with reference to the accompanying drawings, wherein: Figure 1 is a perspective view of one embodiment of a para-kart chassis, in accordance with the present invention,

Figure 2a is a schematic elevational view of the camber adjustment means of the para-kart shown in Figure 1, Figure 2b is a schematic front view of the camber adjustment means shown in figure 2a, Figure 3a is a schematic plan view of part of a rear axle arrangement of the para-kart shown in Figure 1, Figure 3b is a schematic front view of the part of the rear axle arrangement shown in Figure 3a, Figure 3c is a schematic side view of the part of the rear axle arrangement shown in Figure 3a, Figure 3d is an enlarged diagrammatic sectional view along line A-A of Figure 3a, Figure 4 is a schematic plan view of another part of the rear axle arrangement of the para-kart shown in Figure 1, Figure 5a is a schematic plan view of a neck portion of the para-kart shown in Figure 1,

Figure 5b is a schematic front view of the headstock shown in Figure 5a, and Figure 6 is a schematic elevational view of rake angle adjustment means of the para-kart shown in Figure 1.

Referring firstly to Figure 1, a para-kart chassis 10 shown therein is typically formed from metal, such as stainless steel and/or titanium, and comprises a rear axle arrangement 12, a front axle arrangement 14, and a support frame 16 which supports the rear axle arrangement 12 at one end and which supports the front axle arrangement 14 at the other end through a neck portion 18.

The rear axle arrangement 12 includes an axle element 20 having a wheel 22 rotatably mounted at each end, means between the axle element 20 and each wheel 22 for selectively adjusting the camber of each wheel 22, and means for selectively adjusting the toe of the wheels 22.

Referring to Figures 2a and 2b, the camber adjustment means includes a fixed part 24 which is fixed, for example by welding or bolting, to the end of the axle element 20, and a pivotable part 26 which is mounted for pivotable movement on the fixed part 24 about point P. The wheel 22 is rotatably mounted on the pivotable part 26.

The camber adjustment means also includes a camber locking mechanism, schematically shown at 28, by which the pivotable part 26 can be releasably fixed

relative to the fixed part 24, and a guide slot 30 which is formed in the fixed part 24 and through which a projecting element 32 can project from the pivotable part 26 and travel in the guide slot 30. Through the guide slot 30 and the projecting element 32, an amount of camber of the wheel 22 between a maximum and minimum can be set.

The camber locking mechanism 28 is generally in the form of a screwthreaded clamping arrangement. The projecting element 32 acts as part of the screwthreaded clamping arrangement and is in the form of a screw-threaded element which passes through both the fixed part 24/guide slot 30 and the pivotable part 26 to receive a nut element (not shown) on its stem end. The projecting element 32 and nut element can thus be tightened together to releasably clamp the pivotable part 26 to the fixed part 24. When tightened, this prevents the projecting element 32 from moving along the guide slot 30.

Since the fixed and pivotable parts 24 and 26 are of hollow construction, a bearing spacer 27 may be used to prevent the walls of the fixed and pivotable parts 24 and 26 from being deformed when tightening the screw-threaded clamping arrangement.

The toe adjustment means includes a tube element 34, through which the axle element 20 is received, and a displacement locking mechanism 35 by which the axle element 20 can be releasably fixed relative to the tube element. The tube element 34 enables the axle element 20 to be angularly displaced about its longitudinal axis, and also to be axially displaced relative to the support frame 16. The displacement locking

mechanism 35 is in the form of two manually operated elongate screw-threaded elements 35a (one diagrammatically shown in part in Figure 3d) threadably engaged with the tube element 34 through its wall. When operated, the screw-threaded elements 35a can be engaged with the rear-axle element 20.

The rear axle arrangement 12 also includes a suspension linkage 36 through which the rear axle arrangement 12 is pivotably connected to the support frame 16.

The suspension linkage 36 comprises two trailing-arm members 38 which, at one end, are fixed in spaced relationship to the tube element 34 and which, at the other end, are supported for pivotable movement by the support frame 16.

The suspension linkage 36 further comprises damping means in the form of shock absorbers 40 (shown in Figure 1). Each shock absorber 40 interconnects a respective trailing-arm member 38 to the support frame 16.

The rear axle arrangement 12 acts as an anti-roll mechanism.

So that the ride height of the chassis 10 can be adjusted, means are provided by which each shock absorber 40 can be selectively re-positioned. The ride-height adjustment means is in the form of a plurality of attachment positions. A single attachment position 42 is formed on the support frame 16, vertically or substantially vertically adjacent the pivotable connection of each trailing-arm member 38 to the support frame 16, and five attachment positions 46 are formed spaced along the longitudinal extent of each trailing-arm member 38.

At this point, it should be understood that the use of the terms'vertical'and 'vertically'throughout are intended to be construed as if the chassis 10 were on the ground with all the wheels attached and in contact with the ground.

The number of attachment positions 46 is dependent on the length of the trailing-arm members 38. However, a minimum of two attachment positions 46 and more than five attachment positions 46 could be provided. Furthermore, more than a single attachment position 42 could be provided.

The support frame 16 includes a first frame section 48 and a second frame section 50, both of which engage the neck portion 18. The first and second frame sections 48 and 50 are engaged at a first position 52 which is in the vicinity of, but spaced from, the neck portion 18, and the ends of the first and second frame sections 48 and 50 are fixed to the neck portion 18 at second and third positions 54 and 56, respectively. In use, the first frame section 48 passes below the second frame section 50 at the first position. The second and third positions 54 and 56 are spaced along the longitudinal extent of the neck portion 18, the second position 54 being nearer the rear axle arrangement 12 than the third position 56, and the second position 54 is aligned or substantially aligned with the third position 56. The first, second and third positions 52,54 and 56 thus define a triangular shape when viewed in plan. This effectively increases the load bearing area of the neck portion 18.

To aid the user, the first frame section 48 is shaped at 58 to be able to support or brace the outside of the knee area.

The neck portion 18 is slidably adjustable to enable the wheel base of the chassis 10 to be extended or retracted. The neck portion 18 includes a cylindrical outer element 60, which is supported by the first and second frame sections 48 and 50 at the second and third positions 54 and 56, and an elongate slidable element 62 which is slidably received in the cylindrical outer element element 60. The elongate slidable element 62 supports the front axle arrangement 14 at one end.

The neck portion 18 also includes a locking mechanism 64 which is able to releasably lock or clamp the elongate slidable element 62 relative to the cylindrical outer element 60. The locking mechanism 64 is a manual mechanism comprising two screw-threaded elements 66 (one diagrammatically shown in part in Figure 5b), each received in screw-threaded engagement through a wall of the outer cylindrical element 60. The locking mechanism 64 operates in two directions perpendicular or substantially perpendicular to each other.

In a modification to the neck portion locking mechanism 64, the screwthreaded elements 66 are received in screw-threaded engagement through one longitudinal bottom edge of the cylindrical outer element 60. The screw-threaded elements 66 are in spaced relationship and extend in parallel or substantially in parallel through the edge in a direction which is at or substantially at 45 to the included contiguous surfaces of the outer element 60. The locking mechanism 64 thus operates to releasably clamp the elongate slidable element 62 at two spaced points.

It is advantageous to have releasable clamping at two spaced points should

there be any unwanted deformation in the longitudinal extent of the cylindrical outer element 60 which may act as a fulcrum about which the elongate slidable element 62 would tend to pivot should it be only clamped in one place.

The front axle arrangement 14 includes a steerable front fork element 68, means interposed between the front fork element 68 and elongate slidable element 62 of the neck portion 18 by which the rake angle of the front fork element 68 can be adjusted, and a front wheel 69 rotatably mounted on the front fork element 68.

The rake angle adjustment means is similar to the camber adjustment means and includes a fixed part 70 which is fixed to the end of the elongate slidable element 62 and a pivotable part 72 which is pivotably mounted on the fixed part 70 for rake angle movement in the vertical plane of the elongate slidable element. To enable steering, the front fork element 68 is mounted on the pivotable part 72 for pivotable movement which is transverse or substantially transverse to the rake angle movement.

The rake angle adjustment means also includes a rake angle locking mechanism 74 by which the pivotable part 72 can be releasably fixed relative to the fixed part 70, guide slot 76 formed in the fixed part 70, and a projecting element 78 which projects from the pivotable part 72 and travels in the guide slot 76. Through the guide slot 76 and the projecting element 78, an amount of rake angle of the front fork element 68 between a maximum and minimum can be set.

The rake angle locking mechanism 74 is generally in the form of a screw-

threaded clamping arrangement. The projecting element 78 acts as part of the screwthreaded clamping arrangement and is in the form of a screw-threaded element which passes through both the fixed part 70/guide slot 76 and the pivotable part 72 to receive a nut element (not shown) on its stem end. The projecting element 78 and nut element can thus be tightened together to releasably clamp the pivotable part 72 to the fixed part 70. When tightened, this prevents the projecting element 78 from moving along the guide slot 76.

Since the fixed and pivotable parts 70 and 72 are of hollow construction, a bearing spacer 79 may be used to prevent the walls of the fixed and pivotable parts 70 and 72 from being deformed when tightening the screw-threaded clamping arrangement.

As seen in Figure 1, the front fork element 68 includes a pair of stirrups 80 which are releasably attached to the arms 82 of the front fork element 68. Each stirrup 80 is in the form of a bent elongate peg having an adjustable strap 84 positioned thereacross under which a foot of the user can be positioned. Each arm 82 is provided with a plurality of attachment positions 86 spaced along the longitudinal extent thereof so that the stirrups can be re-positioned and, due to the bend in each stirrup 80, each stirrup 80 can be oriented to extend away from or towards the support frame 16 and/or the ground.

In use, the para-kart chassis is placed on the ground and a seat (not shown) is mounted on the support frame 16. It is determined whether the chassis 10 is to be set-

up in a racing configuration or a freestyle configuration. The strength and direction of the prevailing wind is then determined in any usual fashion.

The camber of the or each rear wheel 22 is set via the camber adjustment means based on the chassis set-up required and the strength and direction of the prevailing wind. The camber locking mechanism 28 is released and the pivotable part 26 is pivoted about point P relative to the fixed part 24 such that the projecting element 32 travels in the guide slot 30. Once the desired amount of camber is reached, the camber adjustment locking mechanism 28 is re-locked via the projecting element 32 and its associated nut element.

The toe of the or each wheel is then set via the toe adjustment means based on the chassis set-up required and the strength and direction of the prevailing wind. The displacement locking mechanism 35 is released so that the rear axle element 20 can be angularly displaced relative to the tube element 34. This has the effect of angularly displacing the fixed part 24 of the camber adjustment means from the vertical. Since a camber has been set, the angular displacement of the fixed part 24 results in the wheels 22 having toe.

The rear axle element 20 may also be axially displaced relative to the support frame 16 so that the wheels 22 are asymmetrically positioned relative to the support frame 16. This is particularly beneficial when requiring a racing set-up as the rear axle element 20 can be off-set into the prevailing wind which results in an increased moment being required to be exerted by the wind in order to destabilise the in use

chassis 10.

The displacement locking mechanism 35 is then re-locked via screw-threaded elements 35a.

The ride-height of the chassis 10 can be adjusted using the ride-height adjustment means and/or the rake angle adjustment means based on the desired set-up and the strength and direction of the prevailing wind. The shock absorbers 40 of the damping means are re-positioned along the trailing-arm members 38 of the suspension linkage 36.

The rake-angle adjustment means is utilised to further adjust the ride-height of the chassis 10. The rake-angle locking mechanism 74 is released and the pivotable part 72 is pivoted relative to the fixed part 70 such that the projecting element 78 travels in the guide slot 76. Once the desired amount of rake-angle is reached, the rake-angle locking mechanism 74 is re-locked via the projecting element 78 and its associated nut element.

Generally, for a racing set-up, a lower ride-height and a firmer suspension is required. Consequently, the shock absorbers 40 would be positioned at an attachment position 46 which is closer to the tube element 34 and a large rake-angle would be set. Conversely, for a freestyle set-up, a higher ride-height and a softer suspension is generally required. As such, the shock absorbers 40 would be positioned at an attachment position 46 which is further from the tube element 34 and a smaller rake

angle would be set to enable more responsive steering and a smaller turning circle.

The wheel-base length is then adjusted, again depending on the chassis set-up required and the strength and direction of the prevailing wind. The wheel-base length is adjusted via the neck portion 18. The neck portion locking mechanism 64 is released via the screw-threaded elements 66, allowing the elongate slidable element 62 to be slid within the cylindrical outer element 60. Once the desired wheel-base length is reached, the neck portion locking mechanism 64 is re-locked via the screwthreaded elements 66.

Generally, for a racing set-up, a longer wheel-base length is desirable, and for a freestyle set-up, a shorter wheel-base length is required. However, the wheel-base length is also dictated by the overall height of the user and in particular the length of the legs.

The stirrups 80 are also set depending on the height and preference of the user. Where a large rake-angle is used and the stirrups 80 are set near the axle of the front wheel 69, the orientation must be such that, during turning of the front fork element 68, the stirrup 80 on the inside of the turn does not contact the ground. The angle at which the stirrups 80 are bent is thus important, as is the orientation set by the user.

The re-positionable stirrups 80 also provide for users of varying heights and their individual preferences when setting up the chassis 10.

During use, due to the camber and the toe of the chassis 10 being settable, any downward movement of the chassis 10 relative to the wheels 22, for example when a strong gust of wind catches the para-sail and the user is forced to brace his or her body causing movement of the suspension, results in the tube element 34 being angularly displaced about its longitudinal axis. This angular movement is transmitted to the wheels 22, through the rear axle element 20, the fixed part 24 and the pivotable part 26, and results in the toe of the wheels 22 being dynamically adjusted in a toe-in direction. This assists the user in steering against and counter-acting the unbalancing and destabilising force of the wind.

It should be realised that these embodiments are not limited to a para-kart chassis and could be applied to any suitable wind powered vehicle, such as a chassis incorporating a sail.

It should also be understood that, although the chassis has been described as having wheels, any suitable ground engaging means could, instead of or in addition to, be utilised, such as skis, skates, rollers, tracks, or any combination thereof.

In this respect, the front fork element may be appropriately dimensioned or configured to accept a different ground engaging means, such as a ski or skate, and the stirrups may be fixable to a single elongate stem being part of the front fork element and which interconnects the arms of the front fork element to the neck portion.

It is therefore possible to prevent or inhibit a wind powered vehicle, such as a para-kart, having a chassis as described above being pulled off-line and/or unintentionally destabilised when being subjected to a crosswise or substantially crosswise wind force. It is also possible to provide a wind-powered vehicle, such as a para-kart, having a chassis as described above which can be used as a racing chassis and as a freestyle chassis. It is further possible to provide a wind-powered vehicle, such as a para-kart, having a chassis as described above that can be configured in one or more ways to suit an individual user.

The embodiments described above are given by way of example only and various modifications will be apparent to persons skilled in the art without departing from the scope of the invention. For example, the suspension linkage could be dispensed with and the support frame attached directly to the tube element in such a manner that any downward movement of the support frame causing the rear axle element to flex would result in slight dynamic adjustment of the toe; and, for a chassis having two wheels at the front, the rear axle arrangement could, instead of or in addition to, be provided at the front.

Claims

1. A steerable wind-powered vehicle chassis for use with a para-kart, the chassis comprising a support frame and an axle arrangement supported by the support frame and on which ground engaging means is mounted, the axle arrangement including an axle element, means between the axle element and the ground engaging means for selectively adjusting the camber of the ground engaging means, and means for selectively adjusting the toe of the ground engaging means.

2. A chassis as claimed in claim 1, wherein the chassis is a para-kart chassis.

3. A chassis as claimed in claim 1 or claim 2, wherein the axle arrangement is a rear axle arrangement, and the ground engaging means is in the form of a wheel, the rear axle arrangement having one said wheel rotatably mounted at each end of the axle element.

4. A chassis as claimed in claim 3, wherein the rear axle arrangement further includes a suspension linkage through which the rear axle arrangement is pivotably connected to the support frame.

5. A chassis as claimed in claim 4, wherein the camber adjustment means includes a fixed part fixed to the rear axle element and a pivotable part mounted for pivotable movement on the fixed part, the wheel being rotatably mounted on the pivotable part.

6. A chassis as claimed in claim 5, wherein the camber adjustment means further includes a camber locking mechanism by which the pivotable part can be releasably fixed relative to the fixed part.

7. A chassis as claimed in claim 5 or claim 6, wherein the camber adjustment means also includes a guide slot formed in the fixed part and a projecting element which projects from the pivotable part and travels in the guide slot so that a maximum and a minimum amount of camber can be set.

8. A chassis as claimed in claim 7 when dependent on claim 6, wherein the projecting element forms part of the camber locking mechanism such that, when the camber locking mechanism is locked, the projecting element is prevented or substantially prevented from moving along the guide slot.

9. A chassis as claimed in any one of claims 5 to 8, wherein the toe adjustment means enables the rear axle element to be angularly displaced about its longitudinal axis so that the fixed part can be offset from the vertical to enable toe of the wheel.

10. A chassis as claimed in claim 9, wherein the toe adjustment means includes a tube element, through which the rear axle element is received, and a displacement locking mechanism by which the rear axle element can be releasably fixed relative to the tube element.

11. A chassis as claimed in claim 10, wherein the tube element enables the rear

axle element to be axially displaced relative to the support frame, and the angular displacement locking mechanism can releasably fix the rear axle element in its displaced state.

12. A chassis as claimed in any one of claims 4 to 11, wherein the suspension linkage enables dynamic adjustment of the toe of the said wheel.

13. A chassis as claimed in claim 12, wherein the suspension linkage includes a trailing-arm member which is supported for pivotable movement by the support frame.

14. A chassis as claimed in claim 13 when claim 12 is dependent on claim 10 or claim 11, wherein the trailing-arm member is fixed to the tube element.

15. A chassis as claimed in claim 14, wherein the suspension linkage also includes means by which the ride height of the chassis can be adjusted.

16. A chassis as claimed in 15, wherein the ride height adjustment means includes damping means which interconnects the trailing-arm member and the support frame, the damping means being adjustable to set the ride height of the chassis and the firmness of the suspension linkage.

17. A chassis as claimed in claim 16, wherein the damping means is in the form of a shock absorber, and the ride height adjustment means includes a plurality of

attachment positions at which the shock absorber can be selectively attached between the support frame and the trailing-arm member.

18. A chassis as claimed in claim 17, wherein the plurality of attachment positions includes a single attachment position on the support frame and two or more attachment positions spaced along the longitudinal extent of the trailing-ann member.

19. A chassis as claimed in any one of claims 13 to 18, wherein the suspension linkage has two trailing-arm members.

20. A chassis as claimed in claim 19 when dependent on claim 17 or claim 18, wherein one said shock absorber is associated with each trailing-arm member.

21. A chassis as claimed in any one of claims 4 to 20, further comprising a front axle arrangement which is supported by the support frame through a neck portion and which rotatably supports another wheel, the support frame including a first frame section and a second frame section which engage the neck portion so that the load is spread therebetween.

22. A chassis as claimed in claim 21, wherein the first and second frame sections meet in fixed engagement at a first position spaced from the neck portion, and the ends of the first and second frame sections are fixed to the neck portion at second and third positions, respectively, which are spaced from each other along the longitudinal extent of the neck portion, the first, second and third positions defining a triangular

shape.

23. A chassis as claimed in claim 22, wherein the first and second frame sections cross at the first position, in use the first frame section passing beneath the second frame section.

24. A chassis as claimed in claim 22 or claim 23, wherein the second position is nearer the rear axle arrangement than the third position.

25. A chassis as claimed in any one of claims 21 to 24, wherein the first frame section is shaped to be able to support or brace the outside of the knee area of the user.

26. A chassis as claimed in any one of claims 21 to 25, wherein the neck portion is slidably adjustable to extend and reduce the wheel base of the chassis.

27. A chassis as claimed in claim 26, wherein the neck portion has a neck portion locking mechanism which can releasably clamp the adjustable neck portion at two places.

28. A chassis as claimed in claim 27, wherein the neck portion includes a cylindrical outer element supported by the support frame, an elongate sliding element which is slidably received in the cylindrical outer element and which at one end supports the front axle arrangement, the said two places being spaced along one

longitudinal edge of the cylindrical outer element.

29. A chassis as claimed in any one of claims 21 to 28, wherein the front axle arrangement includes a steerable front fork element and means interposed between the front fork element and the neck portion for adjusting the rake angle of the front forks.

30. A chassis as claimed in claim 29, wherein the rake angle adjustment means includes a fixed part fixed to the neck portion and a pivotable part mounted for pivotable rake angle movement on the fixed part, the front fork element being mounted on the pivotable part for pivotable movement in a direction transverse or substantially transverse to the rake angle movement so that the front axle arrangement can be steered.

31. A chassis as claimed in claim 30, wherein the rake angle adjustment means further includes a rake angle locking mechanism by which the pivotable part can be releasably fixed relative to the fixed part.

32. A chassis as claimed in claim 30 or claim 31, wherein the rake angle adjustment means also includes a guide slot formed in the fixed part and a projecting element which projects from the pivotable part and travels in the guide slot so that a maximum and a minimum amount of rake angle can be set.

33. A chassis as claimed in claim 32 when dependent on claim 31, wherein the projecting element forms part of the rake angle locking mechanism such that, when

the rake angle locking mechanism is locked, the projecting element is prevented or z : l substantially prevented from moving along the guide slot.

34. A chassis as claimed in any one of claims 29 to 33, wherein the front fork element includes a pair of stirrups which are releasably attachable to the arms of the front fork element at different positions along the longitudinal extent of the front fork element so as to accommodate users of different heights.

35. A chassis as claimed in claim 34, wherein each stirrup is in the form of bent elongate element and, when the front forks are in a straight ahead position, can be oriented to extend away from or towards the support frame and/or the ground.

36. A steerable wind-powered vehicle chassis for use with a para-kart, the chassis comprising a support frame and an axle arrangement supported by the support frame and on which ground engaging means is mounted, the axle arrangement including means for preventing or inhibiting the chassis being pulled off-line and/or unintentionally destabilised when in use.

37. A method of preventing or inhibiting a steerable wind-powered vehicle, using a chassis in accordance with any one of claims 4 to 35, being pulled off-line and/or unintentionally destabilised, the method comprising the steps of: a) determining the strength and direction of the prevailing wind;

38. A method as claimed in claim 37 when using a chassis in accordance with any one of claims 29 to 35, further comprising a step subsequent to step (a) of setting the ride height using the ride height adjustment means and/or the rake angle adjustment means based on the strength and direction of the prevailing wind.

39. A method of configuring a steerable wind-powered vehicle, having a chassis in accordance with any one of claims 4 to 35, for use as a racing chassis and as a freestyle chassis, the method comprising the steps of: a) determining which chassis set-up is required;

40. A method as claimed in claim 39 when using a chassis in accordance with any one of claims 21 to 35, further comprising a step subsequent to step (a) of setting the wheel-base length, based on the chassis set-up required, using the adjustable neckportion.

41. A method as claimed in claim 39 or claim 40 when using a chassis in accordance with any one of claims 29 to 35, further comprising a step subsequent to

step (a) of setting the ride height, based on the chassis set-up required and the strength and direction of the prevailing wind, using the ride height adjustment means and/or the rake angle adjustment means.

42. A method as claimed in any one of claims 39 to 41 when using a chassis in accordance with any one of claims 12 to 35 when claim 12 is dependent on claim 11, further comprising a step subsequent to step (a) of axially displacing the rear axle element relative to the support frame based on the chassis set-up required and the strength and direction of the prevailing wind.

43. A steerable wind-powered vehicle chassis for use with a para-kart, the chassis comprising a support frame, an axle arrangement supported by the support frame and on which a ground engaging means is mounted, and a suspension linkage interconnecting the support frame and the axle arrangement, the suspension linkage including a trailing-arm member which is supported for pivotable movement at or adjacent to one end by the support frame and which is fixed to the axle arrangement at or adjacent to its other end.

44. A chassis as claimed in claim 43, wherein the axle arrangement is a rear axle arrangement, and the ground engaging means is in the form of a wheel, the rear axle arrangement having one said wheel rotatably mounted at each end of the axle element.

45. A chassis as claimed in claim 44, wherein the suspension linkage also includes

means by which the ride height of the chassis can be adjusted.

46. A chassis as claimed in claim 45, wherein the ride height adjustment means includes damping means which interconnects the trailing-arm member and the support frame, the damping means being adjustable to set the ride height of the chassis and the firmness of the suspension linkage.

47. A chassis as claimed in claim 46, wherein the damping means is in the form of a shock absorber, and the ride height adjustment means includes a plurality of attachment positions at which the shock absorber can be selectively attached between the support frame and the trailing-arm member.

48. A chassis as claimed in claim 47, wherein the plurality of attachment positions includes a single attachment position positioned on the support frame and two or more attachment positions spaced along the longitudinal extent of the trailing-arm member.

49. A chassis as claimed in any one of claims 42 to 47, wherein the suspension linkage has two trailing-arm members.

50. A chassis as claimed in claim 49 when dependent on claim 47 or claim 48, wherein one said shock absorber is associated with each trailing-arm member.

51. A chassis as claimed in any one of claims 43 to 50, wherein the chassis is a para-kart chassis.

52. A steerable wind-powered vehicle chassis for use with a para-kart, the chassis comprising a support frame, a rear axle arrangement which is supported by the support frame and which supports a ground engaging means, and a front axle arrangement which is supported by the support frame through a neck portion and which supports another ground engaging means, the support frame including a first frame section and a second frame section which engage the neck portion so that the load is spread therebetween.

53. A chassis as claimed in claim 52, wherein the first and second frame sections meet in fixed engagement at a first position spaced from the neck portion, and the ends of the first and second frame sections are fixed to the neck portion at second and third positions, respectively, which are spaced from each other along the longitudinal extent of the neck portion, the first, second and third positions defining a triangular shape.

54. A chassis as claimed in claim 53, wherein the first and second frame sections cross at the first position, in use the first frame section passing beneath the second frame section.

55. A chassis as claimed in claim 53 or claim 54, wherein the second position is nearer the rear axle arrangement than the third position.

56. A chassis as claimed in any one of claims 52 to 55, wherein the first frame section is shaped to be able to support and/or brace the outside of the knee area of the

user.

57. A chassis as claimed in any one of claims 51 to 55, wherein the chassis is a para-kart chassis.

58. A steerable wind-powered vehicle chassis for use with a para-kart, the chassis comprising a support frame, a rear axle arrangement which is supported by the support frame and which supports a ground engaging means, and a front axle arrangement which is supported by the support frame through a neck portion and which rotatably supports another ground engaging means, the neck portion being slidably adjustable to extend and reduce the base length of the chassis.

59. A chassis as claimed in claim 58, wherein the neck portion has a neck portion locking mechanism which can releasably clamp the adjustable neck portion at two places.

60. A chassis as claimed in claim 59, wherein the neck portion includes a cylindrical outer element supported by the support frame, and an elongate sliding element which is slidably received in the cylindrical outer element and which at one end supports the front axle arrangement, the said two places being spaced along one longitudinal edge of the cylindrical outer element.

61. A chassis as claimed in any one of claims 58 to 60, wherein the chassis is a para-kart chassis.

62. A steerable wind-powered vehicle chassis for use with a para-kart, the chassis comprising a support frame, a rear axle arrangement which is supported by the support frame and which supports a ground engaging means, and a front axle arrangement which is supported by the support frame through a neck portion and which rotatably supports another ground engaging means, the front axle arrangement including a steerable front fork element and means interposed between the front fork element and the neck portion for adjusting the rake angle of the front forks.

63. A chassis as claimed in claim 62, wherein the rake angle adjustment means includes a fixed part fixed to the neck portion and a pivotable part mounted for pivotable rake angle movement on the fixed part, the front fork element being mounted on the pivotable part for pivotable movement in a direction transverse or substantially transverse to the rake angle movement so that the front axle arrangement can be steered.

64. A chassis as claimed in claim 63, wherein the rake angle adjustment means further includes a rake angle locking mechanism by which the pivotable part can be releasably fixed relative to the fixed part.

65. A chassis as claimed in claim 63 or claim 64, wherein the rake angle adjustment means also includes a guide slot formed in the fixed part and a projecting element which projects from the pivotable part and travels in the guide slot so that a maximum and a minimum amount of rake angle can be set.

66. A chassis as claimed in claim 65 when dependent on claim 64, wherein the projecting element forms part of the rake angle locking mechanism such that, when locked, the projecting element is prevented or substantially prevented from moving along the guide slot.

67. A chassis as claimed in any one of claims 62 to 66, wherein the chassis is a para-kart chassis.

68. A steerable wind-powered vehicle chassis for use with a para-kart, the chassis comprising a support frame, a rear axle arrangement which is supported by the support frame and which supports a ground engaging means, and a front axle arrangement which is pivotably supported by the support frame for steering and which rotatably supports another ground engaging means, the front axle arrangement including a front fork element and stirrups releasably attached to the front fork elements, the stirrups being fixable at different positions along the longitudinal extent of the front fork element to accommodate users of different heights.

69. A chassis as claimed in claim 68, wherein each stirrup is in the form of bent elongate element and, when the front forks are in a straight ahead position, can be oriented to extend away from or towards the support frame and/or the ground.

70. A chassis as claimed in claim 68 or claim 69, wherein the chassis is a parakart chassis.

71. A steerable wind-powered vehicle chassis for use with a para-kart, the chassis comprising a support frame and an axle arrangement supported by the support frame, the axle arrangement including an axle element, on each end of which a ground engaging means is mounted, and means by which the axle element can be axially displaced so that the said ground engaging means are asymmetrically positioned relative to the support frame.

72. A chassis as claimed in claim 71, wherein the axle arrangement is a rear axle arrangement.

73. A chassis as claimed in claim 71 or claim 72, wherein the axial displacement means includes a tube element, through which the axle element is slidably received, and a locking mechanism by which the axle element can be releasably fixed relative to the tube element.

74. A chassis as claimed in any one of claims 71 to 73, wherein the chassis is a para-kart chassis.

75. A steerable wind-powered vehicle chassis substantially as hereinbefore described with reference to Figure 1, Figures 2a and 2b, Figures 3a to 3d, Figure 4, Figures 5a and 5b, and/or Figure 6 of the accompanying drawings.

76. A para-kart chassis substantially as hereinbefore described with reference to Figure 1, Figures 2a and 2b, Figures 3a to 3d, Figure 4, Figures 5a and 5b, and/or

Figure 6 of the accompanying drawings.