WO2020073090A1

WO2020073090A1 - A structural member

Info

Publication number: WO2020073090A1
Application number: PCT/AU2019/051095
Authority: WO
Inventors: Malcolm Peter Cook; Bryan Tsuen Yan LEE
Original assignee: Ferox Advanced Vehicles Corporation Pty Ltd
Priority date: 2018-10-10
Filing date: 2019-10-10
Publication date: 2020-04-16

Abstract

A structural member 10 comprises a mounting portion 12 on or to which a device, structure, item, or mechanism can be mounted, a first arm 14 and a second arm 16. The first arm 14 extends from the mounting portion 12 and has a first arm end 18 distal from the mounting portion 12. The second arm 16 extends from the mounting portion 12 and has a second arm end 20 distal from the mounting portion. The first and second arms 14, 16 cross over each other at a cross over location 22. The arms 14, 16 also spiral about each other as they extend from the mounting portion 12. Each arm 14 and 16 has a multitude of faces that are predominantly of a quadrilateral or triangular configuration. When in use the first and second arm ends 18 and 20 are coupled to another structure while a device is coupled to the mounting portion 12. The structural member 10 acts to transfer load between the structure to which it is coupled and the device on the mounting portion 12. In one example the structural member 10 can be used as a suspension or drive system component of a vehicle 100 with the first and second arm ends 18, 20 coupled to a chassis of the vehicle 100, a rocker arm 23 mounted on the mounting portion 12 and wheels 102 rotatably supported at opposite ends 58, 60 of the rocker arm 23.

Description

A STRUCTURAL MEMBER

TECHNICAL FIELD

A structural member is disclosed. Embodiments of the structural member enable the load from a device mounted on the structural member to be transferred to another structure to which the structural member is connected.

BACKGROUND ART

Structural members are used in many fields of engineering for transferring or bearing a load. For example, structural members are used in suspension systems for vehicles, in the construction of bridges, airframes for aircraft, high-rise buildings, and heavy machinery such as earthmoving equipment. The strength and rigidity of a structural member may arise from the shape and configuration of one or more individual components from which the structural member is fabricated, or the specific configuration of the components in the structural member. For example, an I beam gives significant structural strength for axial and bending load due to its shape. In another example a box girder provides resistance to torsional load due to its cross-sectional configuration. Structural members in the form of trusses have significant load-bearing characteristics due to a triangular arrangement of its constituent elements.

SUMMARY OF THE DISCLOSURE

In one aspect there is disclosed a structural member comprising:

a mounting portion on which a device can be mounted;

a first arm extending from the mounting portion and having a first arm end distal from the mounting portion;

a second arm extending from the mounting portion and having a second arm end distal from the mounting portion; and

wherein the first and second arms cross over each other at a cross over location.

In one embodiment the first and second arms are connected together at the cross over location.

In one embodiment one of the arms is formed with a recess into which a part of the other arm fits at the cross over location. In one embodiment the first arm end is laterally off set from the second arm end.

In one embodiment the first and second arm ends are laterally offset to opposite sides of the crossover location.

In one embodiment the first arm end and the second arm end are spaced from each other along a common line extending from the mounting portion.

In one embodiment the first arm end and the second arm end are at different elevations with respect to the cross over location.

In one embodiment a central point of respective arm ends, with reference to a Cartesian coordinate system having an origin on a surface of the mounting portion, differ in at least one of their x, y, or z coordinate.

In one embodiment the central point of the respective arms differs in at least two of their x, y, or z coordinates.

In one embodiment the central point of the respective arms differs in every one of their x, y or z coordinates.

In one embodiment first and second arms have different surface areas.

In one embodiment first and second arms occupy different volumes of space.

In one embodiment the first and second arms have a different cross-sectional profile to each other in at least one common plane.

In one embodiment the first and second arms have a different cross section profile in every common plane.

In one embodiment at least one length of the first arm has a box-like section composes of three or four sides.

In one embodiment the structural member comprises a conduit or channel extending internally of the structural member for at least a portion of the length of one or both of the first arm and the second arm. In one embodiment the conduit or channel is arranged to enable a flow of fluid or electric current to a device mounted on the mounting portion.

In one embodiment at least one of the first arm and the second arm follows a generally spiral path from the mounting portion to the respective and portion.

In one embodiment at least one of the first arm and the second arm is formed from a plurality of linear contiguous portions that are angled with respect to each other in a manner so that the corresponding arm follows generally spiral path.

In one embodiment each arm comprises a plurality of faces joined or delimited at mutual edges.

In one embodiment at least some of the faces have a quadrilateral or triangular shape.

In one embodiment faces are formed as individual plates and subsequently jointed together.

In one embodiment the arms are formed from individual beams and/or trusses to have a frame-like structure.

In a second aspect there is disclosed a vehicle comprising:

a body;

at least one structural member according to the first aspect, the at least one structural member coupled to the body; and

one or more wheels coupled with the mounting portion of the at least one structural member.

In one embodiment the vehicle comprises two of the structural members, one of each of the structural members being supported on a left-hand side and a right-hand side of the body.

In one embodiment a first of the structural members has arms which rotate in a clockwise or right-handed direction and a second of the structural members has arms which rotate in an anticlockwise or left-hand direction. In one embodiment the vehicle comprises, for each structural member: a rocker arm pivotally supported by the mounting portion of a corresponding structural member, the rocker arm having a leading end and a trailing end; and, two wheels connected with each rocker arm and in line with each other, one of the wheels at the leading end and another at the trailing end.

In one embodiment the vehicle comprises a powerplant supported by the body and arranged to provide power to drive at least one of the one or more wheels.

In one embodiment the vehicle comprises a wheel motor associated with the at least one of the one or more wheels and supported by a corresponding structural member wherein the powerplant is arranged to transmit power by way of a flow of fluid or electric current through the conduit or channel of the support member to the wheel motor.

In one embodiment first and second arm ends are pivotally connected to the body.

BRIEF DESCRIPTION OF THE DRAWINGS

Notwithstanding any other forms which may fall within the scope of the structural member as set forth in the Summary, specific embodiments will now be described by way of example only with reference to the accompanying drawings in which:

Figure 1 is a schematic representation from one side of one embodiment of the disclosed structural member fitted with an optional rocker arm;

Figure 2 is a front view of the structural member shown in Figure 1 ;

Figure 3 is a perspective view from an opposite side of the disclosed structural member fitted with an optional yoke coupling;

Figure 4 is a perspective view of the structural member shown in Figure 3 but in an alternate viewing plane;

Figure 5 is a plan view of the structural member shown in Figures 3 and 4;

Figure 6 is a front view of the structural member shown in Figures 3-5;

Figure 7 is a bottom view of the structural member shown in Figures 3-6; Figure 8 is a representation of the structural member shown in Figure 1 but with the optional rocker arm removed;

Figures 9a-9d are bottom, left elevation, plan, and right elevation views respectively of a first arm incorporated in the structural member shown in Figures 1 -8;

Figures 10a-10d are bottom, left elevation, plan, and right elevation views respectively of a second arm incorporated in the structural member shown in Figures 1 -8;

Figure 1 1 is a perspective view from an opposite side of the structural member shown in Figure 1 ;

Figure 12 is a schematic representation of a vehicle incorporating embodiments of the disclosed structural member as a component of a suspension system for the vehicle;

Figure 13 is a photograph showing a rear view of a prototype vehicle utilising embodiments of the disclosed structural member; and

DESCRIPTION OF SPECIFIC EMBODIMENT

With reference to Figures 1 -4 an embodiment of the disclosed structural member 10 comprises a mounting portion 12 to which a device, structure, item, or mechanism (herein after referred to collectively and in general as“a device”) can be mounted, a first arm 14 and a second arm 16. The first arm 14 extends from the mounting portion 12 and has a first arm end 18 distal from the mounting portion 12. The second arm 16 extends from the mounting portion 12 and has a second arm end 20 distal from the mounting portion. The first and second arms 14, 16 cross over each other at a cross over location 22. When an embodiment of the structural member 10 is in use the first and second arm ends 18 and 20 are coupled to another structure while a device is coupled to the mounting portion 12. The structural member 10 acts to transfer load between the structure to which it is coupled and the device on the mounting portion 12. To provide context in one example the structural member 10 can be used as a component of a suspension or drive system for a vehicle 100 (shown in Figs 12-14). In such an example the first and second arm ends 18, 20 are coupled to a chassis of the vehicle 100 while a rocker arm 23 is the device mounted on the mounting portion 12. In the illustrated embodiments respective wheels 102 are rotatably supported at opposite ends of the rocker arm 23. The structural member 10 is configured so that both the arm ends 18, 20 are on the same side of the mounting portion 12. Also, as will be explained in greater detail below the arms 14, 16 also spiral about each other as they extend from the mounting portion 12.

To assist in describing the geometry of the structural member 10 a Cartesian coordinate system is shown on some of the Figures having mutually orthogonal x, y and z axes with an origin (0,0,0) at an arbitrary location. In this example the arbitrary location is a point on a surface of the mounting portion 12. A central point 24 at the first arm end 18 has a coordinate (x1 , y1 , z1 ) while a central point 26 at the second arm end 20 has a coordinate (x2, y2, z2).

As shown in Figure 2 the first and second arm ends 18, 20 are laterally offset from each other; the central points 24, 26 being spaced apart other along the Z axis. In terms of their coordinates the central points 24, 26 have different z coordinates, z1 and z2. Additionally, the central points 24, 26 are on opposite sides of the crossover location 22 which includes a point 28 with a coordinate (x3, y3, z3).

In this embodiment the first and second arm ends 18, 20 and thus their central points 24, 26 are also at different elevations with respect to each other, as is evident from the central points 24, 26 being spaced along the y-axis. That is, the central points 24 and 26 have different y coordinates y1 and y2. The central points 24 and 26 are on opposite sides of the crossover location 22. So, the coordinate y3 of the point 28 is intermediate the coordinates y1 and y2 along the y-axis.

In this embodiment the arms 14 and 16 reach out to different distances from the mounting portion 12. This is evident from Figure 1 which shows the second arm end 18 extending in the x-axis direction further than the second arm end 20. Accordingly, central points 24, 26 have different x coordinates x1 , x2.

From the above it will be understood that with reference to the Cartesian coordinate system having an origin (0, 0, 0) at an arbitrary location on the surface of the mounting portion 12 the central points 24, 26 of the first and second arms 14 and 16 differ in at least one of their x, y, z coordinates. In the specific embodiment the central points 24 and 26 differ in each of their x, y, z coordinates. The arms 14 and 16 are also different to each other in terms of their shape, configuration, surface area and volume. In general terms the first arm 14 is“bigger” than the second arm 16. More specifically the first arm 14 has a greater surface area and occupies a greater volume of space than the first arm 16. The difference in the arms 14 and 16 is also manifested in their cross-sectional profiles in a common plane parallel to the Z axis. In at least one of these planes the arms 14 and 16 have a different profile. More particularly the difference in profile exists in at least two planes, one to each side of the crossover location 22. Indeed, for the presently illustrated embodiment the arms 14 and 16 have different profiles in every common plane parallel to the z-axis.

Each of the arms 14 and 16 comprises a multitude of faces. At least some of the faces are of a quadrilateral or triangular configuration. Indeed, in this embodiment most of the faces have a quadrilateral or triangular configuration. In this embodiment the first arm 14 comprises thirty six (36) distinct faces, while the second arm 16 comprises twenty (20) distinct faces. The incorporation of the triangular faces provides significant structural strength to the respective arms 14, 16 and the structural member 10.

Figures 9a -1 Od identify each of the distinct faces of the arms 14 and 16. Each face is denoted by a reference PL1 -PL58. The shape of each face is set out in the table below.

At the end of the arms 14, 16 there are respective connecting members which in this embodiment take the form of cylindrical bosses 30 and 32 respectively. In an exemplary application where the structural member 10 is used as a component of a vehicle suspension mounting pins (not shown) pass centrally through the bosses 30 and 32 to connect to the structural member 10 to the vehicle 100. The connections through the bosses 30, 32 can be arranged to enable pivotal motion about one or both of the mounting pins.

There are at least four triangular faces at each of the arm ends 18 and 20 for attachment to the connecting members/bosses 30, 32. Moreover in this embodiment there are eight triangular faces at each of the ends 18 and 20 to connect the arms to the bosses 30 and 32. End 18 comprises faces PL33-PL39, and PL49; while end 20 comprises faces PL41 -PL48.

As previously mentioned the arms 14 and 16 spiral about each other as they extend from one end to the other. The spiralling is represented in Figures 5, 6 and 7 by the use of dashed lines and arrows extending along the respective arms 14 and 16. The spiralling of the arms 14 and 16 is produced by incremental changes in direction of linear contiguous portions of the arms, rather than by forming the arms as smoothly curved and spiralling elements. The contiguous portions are generally joined together or delimited along linear seams or edges. At least some of the portions may have a quadrilateral box like profile; while others are composed of generally triangular elements or substructures; yet other portions may have a polygonal prism or box like configuration. Thus, as is clear from the enclosed drawings embodiments of the structural member 10 are formed with multiple linear seams or edges between or otherwise delimiting adjacent faces. This forms relatively clear edges or boundaries between adjacent faces rather than continuous rather than non-distinct continuous or curved transitions between adjacent faces. Also, the portions of the structural member 10, which are formed from a plurality of faces, are coupled together or juxtaposed with distinct changes of direction, rather than continuous or curved. This aspect may be most apparent when the structural member 10 is made for a plurality of district preformed plates that are subsequently fixed together. However, this is not to say that tight radii may be subsequently formed by for example sanding or polishing the edges to remove burrs or rough edges. The direction of the spiral of the arms in the structural member 10 can be either right-handed or left-handed. In the embodiment of the arm 10 shown in Figures 1 -1 1 the direction of the spiral looking in the direction from the bosses 30, 32 to the mounting portion 12 is in the anti clockwise or left-handed direction. This direction is most prominently displayed by the arm 14. Generally, when structural members 10 are used in opposed pairs, their direction of spiral will also be opposite; that is one of the structural members 10 will have a right-handed spiral while the other will have a left-handed spiral. It is believed that this configuration gives greater torsional bending resistance. An example of this will be provided later with reference to Figures 12 and 13.

In general terms starting from the mounting portion 12 the arm 14 extends upwardly and away from the mounting portion 12 so that prior to the crossover location 22 a portion of the arm 14 is nominally above and to one side of the arm 16. This extension is created by a shoulder portion 40 that is made up from a plurality of the faces PL5-PL12, PL17-20, PL22, PL50, PL51 , PL55 and PL56. The arm 14 then has a contiguous short portion 42 formed of the faces PL2, PL3, PL13, PL16, and PL52 which is angled back toward the mounting portion 12. The arm 14 then has a further long contiguous portion 44 that is angled with respect to the portion 42 further toward the mounting portion 12 and crosses over the second arm 16. The portion 44 comprises faces PL1 , PL4, PL14 and PL15. The distal end of portion 44 terminates with the end portion 18 and is comprised of eight triangular faces PL33-PL39, and PL49 and is attached to the boss 30. The end portion 18 is angled with respect to the portion 44 away from the mounting portion 12 and back toward the second arm 16.

The portion 44 which makes up the longest length potion of the arm 14 has four sides and a quadrilateral box-like cross section. However, the cross-section is not of a constant perimeter or profile in every plane along the length of the portion 44. The length of the perimeter increases in a direction away from the mounting portion 12. In this embodiment this is achieved by having upper and lower sides of the portion 44 increase in width as the arm 14 extends away from the mounting portion 12. This can be seen in Figure 5 where W2>W1 .

The arm 16 has a shoulder portion 46 comprising seven faces PL23, PL25, (part of) PL28, (part of) PL53, PL54, PL57 and PL58. The shoulder portion 46 is connected to the mounting portion 12 and is of a much simpler configuration that the shoulder portion 40. This is followed by a contiguous short portion 48 formed of the four faces PL31 , PL24 (part of) PL28, (part of) PL53. The shoulder 46 and short portion 48 extend at a slight angle away from the mounting portion 12. This is followed by a contiguous portion 50 formed of the five faces PL26, PL27, PL29, PL30 PL40 which makes up the majority of the length of the second arm 16. The portion 50 is angled with reference to the portion 48 further away from the mounting portion 12. The distal end of the portion 50 terminates with the end portion 20 which comprises eight triangular faces PL41 -PL48 and is attached to the boss 32. The end portion 20 is angled with respect to the portion 50 toward from the mounting portion 12 and the first arm 14.

The portion 50 has four sides/faces and a quadrilateral box-like cross section. However, the cross-section is not of a constant perimeter in every plane transverse to the length of the portion 50. The length of the perimeter increases in a direction away from the mounting portion 12. In this embodiment this is achieved by having all four sides/faces of the portion 50 of increasing width as the arm 16 extends away from the mounting portion 12. This can be seen by Figure 4 where W6>W4 and Fig 8 where W5>W3.

To enhance rigidity and strength of the structural member 10 the arms 14 and 16 can optionally be mutually engaged or otherwise connected at the crossover location 22. One way of making a connection is by welding. Mutual engagement can be facilitated by providing at least one of the arms with a recess into which a part of the other arm fits at the crossover location. In this embodiment the arms 14 and 16 inter-fit (also known as“form fit”) at the crossover location 22 as can be seen in Figures 2, 6 and 7. The first arm 14 is provided with a recess or cut out 34 (see Figures 9a and 9b). The second arm 16 is also provided with a recess or cut out 36 (see Figures 10a and 10d). The recesses 34 and 36 are configured so that their edges abut each other when the arms crossover at the crossover location 22. The mutually abutting edges of the recesses can be welded together to form a fixed connection between the arms 14 and 16.

The recess 34 is formed in this embodiment by making a cut in or otherwise shaping two faces PL1 and PL15. The recess 36 is formed by providing a space or gap between the two faces PL26 and PL40; and, making a cut or notch in a third plate PL30.

In its most basic form the mounting portion 12 is in the form of a plate 52 as shown in Figures 8, 10b and 10d to which a device can be attached or otherwise mounted. In this form a wheel for example could be mounted on the plate 52 by fixing a stub axle to the plate 12. However, in the embodiment shown in Figures 1 , 2 and 1 1 the rocker arm 23 can be considered as the device attached to the mounting portion 12. In this specific example the rocker arm 23 is pivotally mounted on an axle 54 supported by a plate 56 that in turn is attached, for example by bolting, to the mounting portion 12/plate 52. As previously described in this embodiment respective wheels are rotatably attached by way of respective axles (not shown) supported at opposite ends 58 and 60 of the rocker arm 23.

Figures 3 and 5-7 depict a yoke 62 that is attached to the mounting portion 12/plate 52. The yoke 62 is yet another example of a device, or part of a device that can be mounted on the mounting portion 12. The yoke 62 provides an alternate method for coupling another component or device to the structural member 10.

The structural member 10 can be provided with internal conduits and/or channels for supplying power and control signals to devices mounted on the mounting portion 12. For example, one or both of the arms 14 and 16 can be provided with internal conduits or hoses for supplying fluid to and from a hydraulic motor or machine coupled to the mounting portion 12. Alternately the internal conduits may house cables for supplying electric current to an electric motor or machine coupled to the mounting portion 12.

Due to the internal volume of the arms 14 and 16 it should be appreciated that conduits within any one of the arms can be formed of a shape and configuration different to that of the corresponding arm. For example, a flexible hose can be“threaded through” the length of arm 14 from an opening (not shown) in the end 18 or the boss 30 and exit through a hole in the shoulder portion 40 for connecting with a hydraulic motor coupled to the mounting portion 12.

In another embodiment the support member 10 can be constructed to have one or more wholly internal conduits and flow galleries that channel hydraulic fluid from: an inlet formed on the arm 14 for example in the boss 30 or a region where the portion 44 joints with the end 18; to internal conduits in the rocker arm 23 to supply hydraulic motors at the ends 58 and 60.

The support member 10 can be made using several different methods. In one method the support member 10 can be made by welding or otherwise attaching together individual plates or pieces of material which constitute the faces PL1 -PL58 of the member 10. In this example 58 individual plates cut or otherwise formed to the shapes of faces PL1 -PL58 can be attached together to form the structural member 10. This technique can be used for example where the construction material is a metal. In another example support member 10 can be made from a composite material such as but not limited to fibre reinforced polymers including glass fibre reinforced polymer and carbon fibre reinforced polymer. Such composite material can be laid up on a wireframe.

Alternately, the support member 10 can be made by an additive manufacturing process such as 3-D printing. Using these manufacturing/construction techniques, the faces remain distinct and delimited by linear edges although small or tight radii may be formed as an inherent consequence of the manufacturing technique.

Figures 12-13 show a motor vehicle 100 incorporating embodiments of two of the structural members which are designated as 10L and 10R respectively. Using the same designation as right-hand drive vehicle and left-hand drive vehicle, the structural member 10L is on a left- hand side of the vehicle while the structural member 10R is on a right-hand side of the vehicle. The structural members 10L and 10R are mirror images of each other. Looking in the direction from the bosses 30, 32 to the mounting portion 12: in the structural member 10L the arms 14 and 16 spiral in an anti-clockwise, or left-handed direction; while in the structural member 10R the arms 14 and 16 spiral in a clockwise direction or right handed. The direction of the spiral is predominately the direction of spiralling of the arm 14.

Each support member 10 is provided as, or a part of, the suspension for one or more (in this example two) rear wheels 102. Respective wheels 102 are rotatably supported at the ends 58 and 60 of the rocker arm 23 coupled to one of the support member 10: which in turn is attached by the arm ends 18, 20 on a right-hand side of the vehicle body or chassis.

Similarly, respective wheels 102 are rotatably supported at the ends 58 and 60 of a rocker arm 23 coupled to a second support member 10 attached via the arm ends 18, 20 to the left- hand side of the vehicle body or chassis. So, there are two in line wheels supported by each of the support members 10.

The vehicle 100 includes a powerplant 103 supported by the vehicle body or chassis. The type of powerplant 103 is of no significance to the working of embodiments of the structural member 10. In this embodiment the powerplant 103 shown is a combustion engine which drives a hydraulic pump (not visible) or an electric generator to produce electricity. However, the powerplant 103 may alternately be a fuel cell which drives a hydraulic pump or charges a bank of batteries. In yet another embodiment the powerplant 103 can be in the form of a bank of rechargeable batteries per se that may optionally drive a hydraulic pump.

In the vehicle the wheels 102 are rear wheels and powered or driven by the powerplant 103. In this embodiment there is no direct mechanical transmission between the powerplant 103 and the rear wheels 102. Rather hydraulic or electric wheel motors 104 associated with each of the wheels 102 and supported by the support members 10 via the connector to rockers 23. The wheel motors 104 receive power via hydraulic fluid or electric current that flows through conduits internal of the arms 14 and/or 16. Thus the vehicle 100 is provided with rear-wheel drive without the need for an axle extending transversely between the right and left sides of the vehicle and without the need of a differential, as in conventional vehicles. This opens up an entirely different design philosophy for vehicles not restricted by transverse axles for providing rear-wheel drive.

While an embodiment of the disclosed support member 10 has been described above it will be apparent that other variations or modifications are possible. For example, the arms 14 and 16 are illustrated as being formed from faces in the form of planar sheets or plates of material forming in essence a closed internal space or volume. However, the arms 14 and 16 can be formed in the same configuration but from individual beams and/or trusses to have a frame-like structure, for example similar to the jib of a crane or a truss bridge. Also, while the arms 14 and 16 are formed with different portions having four sides, for example portion 44 of arm 14 and portion 50 of arm 16, these portions may have different

configurations such as for example having three sides so as to have a generally triangular cross-sectional profile.

The support member 10 is not limited in application to the described vehicle suspension system but is able to be applied in structures and machines where substantial mechanical strength and rigidity is required. In one example a pair of support members 10 can act as the arms of an earthmoving machine between which is supported a bucket.

In the claims which follow and in the preceding description, except where the context requires otherwise due to express language or necessary implication, the word“comprise” and variations such as“comprises” or“comprising” are used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features of the container as disclosed herein.

Claims

1. A structural member comprising:

a mounting portion on which a device can be mounted;

2. The structural member according to claim 1 wherein the first and second arms are connected together at the cross over location.

3. The structural member according to claim 1 or 2 wherein one of the arms is formed with a recess into which a part of the other arm fits at the cross over location.

4. The structural member according to any one of claims 1 -3 wherein the first arm end is laterally off set from the second arm end.

5. The structural member according to claim 4 wherein the first and second arm ends are laterally offset to opposite sides of the crossover location.

6. The structural member according to any one of claims 1 -5 wherein the first arm end and the second arm end are spaced from each other along a common line extending from the mounting portion.

7. The structural member according to any one of claims 1 -6 wherein the first arm end and the second arm end are at different elevations with respect to the cross over location.

8. The structural member according to any one of claims 1 -7 wherein a central point of respective arm ends, with reference to a Cartesian coordinate system having an origin on a surface of the mounting portion, differ in at least one of their x, y, or z coordinate.

9. The structural member according to claim 8 wherein the central point of the respective arms differs in at least two of their x, y, or z coordinates.

10. The structural member according to claim 8 wherein the central point of the respective arms differs in every one of their x, y or z coordinates.

1 1 . The structural member according to any one of claims 1 -10 wherein first and second arms have different surface areas.

12. The structural member according to any one of claims 1 -1 1 wherein first and second arms occupy different volumes of space.

13. The structural member according to any one of claims 1 -12 wherein the first and

second arms have a different cross-sectional profile to each other in at least one common plane.

14. The structural member according to claim 13 wherein first and second arms have a different cross section profile in every common plane.

15. The structural member according to any one of claims 1 -14 wherein at least one length of the first arm has a box-like section composes of three or four sides.

16. The structural member according to any one of claims 1 -15 comprising a conduit or channel extending internally of the structural member for at least a portion of the length of one or both of the first arm and the second arm.

17. The structural member according to claim 16 wherein the conduit or channel is

arranged to enable a flow of fluid or electric current to a device mounted on the mounting portion.

18. The structural member according to any one of claims 1 -17 wherein at least one of the first arm and the second arm follows a generally spiral path from the mounting portion to the respective and portion.

19. The structural member according to claim 18 wherein the at least one of the first arm and the second arm is formed from a plurality of linear contiguous portions that are angled with respect to each other in a manner so that the corresponding arm follows generally spiral path.

20. The structural member according to any one of claims 1 -19 wherein each arm comprises a plurality of faces joined or delimited at mutual edges.

21 . The structural member according to claim 20 wherein at least some of the faces have a quadrilateral or triangular shape.

22. The structural member according to claim 20 or 21 wherein faces are formed as individual plates and subsequently jointed together.

23. The structural member according to claim 20 or 21 wherein faces are formed as individual plates and subsequently jointed together.

24. The structural member according to any one of claims 1 -19 wherein the arms are formed from individual beams and/or trusses to have a frame-like structure.

25. A vehicle comprising:

a body;

at least one structural member according to any one of claims 1 -24, the at least one structural member coupled to the body; and

26. The vehicle according to claim 25 comprising two of the structural members, one of each of the structural members being supported on a left-hand side and a right-hand side of the body.

27. The vehicle according to claim 25 wherein a first of the structural members has arms which rotate in a clockwise or right-handed direction and a second of the structural members has arms which rotate in an anticlockwise or left-hand direction.

28. The vehicle according to claim 25 or 26 comprising, for each structural member: a rocker arm pivotally supported by the mounting portion of a corresponding structural member, the rocker arm having a leading end and a trailing end; and, two wheels connected with each rocker arm and in line with each other, one of the wheels at the leading end and another at the trailing end.

29. The vehicle according to any one of claims 25-27 comprising a powerplant supported by the body and arranged to provide power to drive at least one of the one or more wheels.

30. The vehicle according to claim 28 comprising a wheel motor associated with the at least one of the one or more wheels and supported by a corresponding structural member wherein the powerplant is arranged to transmit power by way of a flow of fluid or electric current through the conduit or channel of the support member to the wheel motor.

31 . The vehicle according to any one of claims 25-29 wherein the first and second arm ends are pivotally connected to the body.