Technical Field

The present invention relates to the field of skateboards, and in particular, the suspension and/or steering of skateboards.

Background of the Invention

Certain prior art skateboards tend to exhibit relatively poor suspension when travelling over varying terrain. Attempts have been made to improve the suspension of these skateboards - for instance by use of leaf springs and the like. However, such arrangements tend to be relatively bulky, and thus, may interfere with the turning movement of the skateboard.

Summary of the Invention

The present invention seeks to alleviate at least one of the problems described above in relation to the prior art.

The present invention may involve several different broad forms. Embodiments of the invention may include one or any combination of the different broad forms herein described.

In a first broad form, the present invention provides a wheel axel for attachment to a skateboard: said wheel axel including a first arm and a second arm for attachment with corresponding wheels; whereby, when attached to the skateboard, the first arm and second arm are each resiliently and independently displaceable relative to the skateboard.

Preferably the first and second arms may be provided by a pair of L-shaped

torsion bars. More preferably the first and second arms may be provided by first portions of the torsion bars. Preferably, the first portions of the torsion bars may extend at right angles to corresponding second portions of their respective torsion bars. Advantageously, the use of torsion bars may provide a relatively compact spring configuration in comparison to alternative prior art spring configurations which are relatively bulky particularly when mounted on an underside of a skateboard.

Preferably the L-shaped torsion bars may each be formed from annealed and untempered spring steel members. Typically, the spring steel members may include straight pieces of around 150 mm in length before being formed into torsion bars. The straight pieces may initially include uniform diameters of around

10 mm. First ends of each straight piece may be machined down to diameters of around 6 mm so as to provide the first portions of the respective torsion bars, and, second ends of the straight pieces may be machined down to diameters of around

8mm so as to provide the second portions of the torsion bars. The first and second portions include lengths of approximately 32 mm and 72 respectively.

Typically, third portions disposed between the first and second portions may include diameters of approximately 10mm.

After being machined down to the appropriate diameters, the straight pieces may thereafter be bent into substantially L-shaped configurations.

Typically thereafter, the second portions of the torsion bars may be welded together substantially in parallel. Typically, the welded second portions may also be welded to a metal frame. The metal frame may typically include a mild steel material. Typically, the first portions of the torsion bars project outwardly of a first end of the frame at right angles to the frame. Advantageously, the frame may provide a protective covering ,for the torsion bars in use. Typically thereafter, a heat treatment may be applied to both the torsion bars and/or the frame after the second portions have been welded together. The step of heat treating the torsion bars and/or frame after they have been welded together may be advantageous in that if the torsion bars are heat treated before being welded together, the welded

join may tend to become unsuitably brittle, and therefore be prone to snapping when a load is applied. Typically, the heat treatment seeks to achieve a degree of hardness in the torsion bars and/or frame of at least about HRC 46 on the Rockwell scale of hardness.

Preferably, the torsion bars include a yield point of at least about 800 Newtons.

Typically, a mounting plate may be secured flush against an underside of a skateboard using screws or the like. The mounting plate typically includes an aluminium material and is generally not heat treated when the torsion bars and/or frame are heat treated.

Typically, the frame may be rotatably coupled to the mounting plate by way of a retaining bolt which passes through an annular portion of the frame and into a first socket disposed on the mounting plate. The annular portion is typically disposed at the first end of the frame. Preferably, a swivel pin extends from the frame and is received in a second socket disposed on the mounting plate. Advantageously, when the surface of the skateboard is tilted, the swivel pin may rotate within the second socket - and consequently, the frame which is coupled to the swivel pin may also rotate through a horizontal turning arc so as to steer the wheels in the direction of the tilt. The turning arc of the frame may vary relatively with the degree of tilt applied to the skateboard. The first and second sockets may be integrally moulded into the mounting plate.

Thus, swivelling motion of the frame relative to the mounting plate may enable steering of the wheel axel in use.

Preferably, when mounted to the skateboard, the welded second portions of the torsion bars may be inclined at an angle of about 30 degrees or less, relative to an underside of the skateboard. Advantageously, this arrangement may further alleviate the occurrence of damage being caused to the torsion bars in use.

Preferably, the first and second arms of the wheel axel include wheel attachment

means. Typically this may include a screw thread means disposed on the first portions of the torsion bars which may be adapted to engage with corresponding screw threads disposed on wheels to be mounted to the skateboard.

In a second broad form, the present invention provides a method of forming a wheel axel for attachment to a skateboard including the steps of:

(i) providing a pair of substantially L-shaped torsion bars each having first and second portions extending substantially at right angles to each other; (ii) thereafter, welding second portions of said torsion bars together to substantially form a T-shaped configuration; (iii) thereafter, tempering the welded torsion bars.

Typically the L-shaped torsion bars may include substantially identical shapes and dimensions..

Typically, the second portions may be welded together substantially in parallel. Preferably, the step of welding the second portions of the torsion bars together also involves the step of welding the second portions to a metal frame which may support and/or protect the second portions in use.

Typically, each torsion bar may be formed from straight pieces of annealed and untempered spring steel members of approximately 10 mm diameter and around 150 mm in length. This may involve the step of machining down first and second ends of the spring steel members to form the first and second portions of the torsion bars at 6mm and 8mm respectively. Thereafter, the spring steel members may be bent substantially into an L-shaped configuration.

Typically, the step of tempering the welded L-shaped torsion bars may include applying a heat treatment. Typically, the heat treatment may be adapted to achieve a hardness rating of at least about HRC 46 in accordance with the Rockwell scale of hardness. Typically, the step of heat treating the welded torsion bars also includes heat treating the frame to which the torsion bars are welded.

The first portions which project outwardly of the frame may provide the first and second arms of the wheel axel. The mounting plate may be secured flush against an underside of a skateboard using screws or the like such that swivelling motion of the frame relative to the mounting plate may allow steering of the wheel axel in use.

Preferably, the step of pivotably mounting the frame to the mounting plate is performed in such a way that the welded second portions of the torsion bars may be inclined at an angle of about 30 degrees or less, relative to the underside of the skateboard.

Preferably, the present invention includes the step of providing a means of releasably attaching at least one wheel to each of the first and second arms of the wheel axel. Typically this may include a screw thread means disposed on the first portions of the torsion bars which may be adapted to engage with corresponding screw threads disposed on wheels to be mounted to the wheel axel of the skateboard.

In a third broad form, the present invention provides a steering assembly for attachment to a skateboard including: a first arm and a second arm for attachment with corresponding wheels; whereby the first arm and the second arms are each resiliently and independently displaceable relative to the skateboard.

In a fourth broad form, the present invention includes a suspension mechanism for attachment to a skateboard including a first arm and a second arm for attachment with corresponding wheels; whereby the first arm and the second arms are each resiliently and independently displaceable relative to the skateboard.

The reference to the word "machining" is taken to refer to the cutting and or

shaping of a material, and in particular, the torsion bars used to form the wheel axel.

Brief Description of the Drawings

The present invention will become more fully understood from the following detailed description of a preferred but non-limiting embodiment thereof, described in connection with the accompanying drawings, wherein:

- Figure 1 depicts a perspective view of an L-shaped torsion bar which is used in accordance with a first embodiment o the present invention;

Figure 2 depicts a perspective view of the wheel axel assembly in accordance with the first embodiment;

Figure 3 depicts a side view of the wheel axel assembly in accordance with the first embodiment;

- Figure 4 depicts a front elevated view of the wheel axel assembly in accordance with the first embodiment;

Figure 5 depicts a bottom view of the wheel axel assembly in accordance with the first embodiment;

Figure 6 depicts a perspective view of the wheel axel assembly attached to a mounting plate of a^skateboard;

Figure 7 depicts a further perspective view of the wheel axel assembly attached to the mounting plate of a skateboard;

Figure 8 depicts a front elevated view of the wheel axel assembly attached to the mounting plate of a skateboard;

Figure 9 depicts a side view of the wheel axel assembly attached to the mounting plate of a skateboard;

Figure 10 depicts a front view of a wheel axel assembly attached to the mounting plate of a skateboard;

Figure 11 depicts a bottom view of a wheel axel assembly attached to the mounting plate of a skateboard;

- Figure 12 depicts a mounting plate used in accordance with the first embodiment of the present invention.

Best Mode for Carrying Out the Invention

Figures 1 to 12 depict various aspects of a first embodiment wheel axel (1) arrangement adapted for attachment to a skateboard. A method of forming the first embodiment wheel axel (1) will be described in detail below.

Firstly, a pair of substantially L-shaped torsion bars (2,2') are formed from straight pieces of annealed and untempered spring steel members of approximately 10 mm uniform diameter and each being around 150 mm in length. Figure 1 shows a first torsion bar (2) which is substantially identical to the second torsion bar (2').

Thereafter, first and second ends of the straight pieces are machined down to form the first portions (2A,2A') and second portions (2B,2B') of the torsion bars (2,2') having diameters of about 6mm and 8mm respectively. The first portions (2A.2A ¹ ) and second portions (2B,2B ^! ) include lengths of approximately 32mm and 72 mm respectively.

Thereafter, the machined spring steel members are bent into substantially identical L-shaped configurations whereby the first portions (2A.2A ¹ ) and second portions (2B,2B') extend substantially at right angles to each other.

Thereafter, the second portions (2B.2B ¹ ) of the torsion bars (2,2') are inserted

through retaining apertures (3B.3B ¹ ) disposed on a first end (3A) of a frame (3), so that the second portions (2B.2B ¹ ) are laid flat against the frame (3) in parallel. The second portions (2B.2B ¹ ) of the torsion bars (2,2') are welded together and also to the frame (3) so that they remain relatively stationary to the frame (3). In this arrangement, the first portions (2A.2A ¹ ) of the torsion bars (2,2') each extend outwardly of the first end (3A) of the frame (3) so as to collectively form a T- shaped configuration. The first portions (2A.2A ¹ ) of the torsion bars (2,2') which project outwardly of the frame (3) are to provide the first and second arms (2A.2A ¹ ) of the wheel axel (1) to which wheels are attached. Figures 2-5 show various aspects of the torsion bars (2,2') welded in position within the frame (3).

Thereafter, a heat treatment is applied to both the welded L-shaped torsion bars (2,2') and the frame (3) to temper their materials. The heat treatment is adapted to achieve a hardness rating of at least about HRC 46 in accordance with the Rockwell scale of hardness.

A mounting plate (4) is adapted for securement flush against an underside of a skateboard using screws or the like. The mounting plate (4) is made from an aluminium material and is not heat treated when the torsion bars (2,2') and frame (3) are heat treated.

The frame (3) is able to be rotatably coupled to the mounting plate (4) using a retaining bolt (5) which passes through an annular portion (6) of the frame (3) and into a first socket (7) disposed on the mounting plate (4). The annular portion (6) is disposed at the first end (3A) of the frame (3). A swivel pin (8) also extends from the frame (3) and is received in a second socket (9) disposed on the mounting plate (4). Thus, when the surface of the skateboard is tilted, the swivel pin (8) rotates within the second socket (9) - and consequently, the frame (3) which is coupled to the swivel pin (8) is also able to be rotated through a horizontal turning arc so as to allow steering of the wheels in the direction of the tilt. The turning arc of the frame (3) is able to vary relatively with the degree of tilt applied to the skateboard. The first and second sockets (7,9) are integrally moulded into the mounting plate (4). Figures 6-11 show various aspects of the wheel axel

assembly (1) attached to the mounting plate (4).

When mounted to the skateboard, the welded second portions (2B.2B ¹ ) of the torsion bars (2,2') should be inclined at an angle of about 30 degrees or less, relative to the underside of the skateboard so as to alleviate the risk of the torsion bars (2,2') being damaged by contact with the ground in use.

The first and second arms (2A,2A') of the wheel axel (1), which are provided by first portions (2A.2A ¹ ) of the torsion bars (2,2), are adapted for screw-thread engagement with a pair of corresponding wheels.

It would also be appreciated by a person skilled in the art that in use, the frame (3) should be arranged relative to the skateboard such that the torsion bars (2,2') are aligned as close to a centre-line of the skateboard as possible in order to alleviate the effects of "bump steering".

In use, any upward force applied to the wheels as they move across a surface, are absorbed by a vertical deflection of the torsion bars (2,2'). This is translated in to the torsional twist of the fixed torsion bars (2,2'). In the same way, whenever a downward force is applied by a user shifting his position on the skateboard, this downward force is translated in to torsional twist in the torsion bars (2,2') as a result of the deflection of the first portions (2A,2A') of the torsion bars (2,2'), from their normal at rest position.

Those skilled in the art will appreciate that the invention described herein is susceptible to variations and modifications other than those specifically described without departing from the scope of the invention. All such variations and modification which become apparent to persons skilled in the art, should be considered to fall within the spirit and scope of the invention as broadly hereinbefore described. It is to be understood that the invention includes all such variations and modifications. The invention also includes all of the steps and features, referred or indicated in the specification, individually or collectively, and any and all combinations of any two or more of said steps or features.

The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that that prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates.