WO2009026626A1

WO2009026626A1 - All-terrain skateboards

Info

Publication number: WO2009026626A1
Application number: PCT/AU2008/001255
Authority: WO
Inventors: Greame Attey
Original assignee: Design Science Pty Ltd
Priority date: 2007-08-27
Filing date: 2008-08-27
Publication date: 2009-03-05

Abstract

An in-line all-terrain skateboard has a forwardmost steering wheel (1) having a hub (5) attached to and rotating with the wheel (1 ). A curved cross-bar (4) extends from the hub (5) in either side of the forwardmost steering wheel (1) so that the wheel (1) can traverse the cross-bar (4) in response to weight shift of a rider so as to steer the skateboard.

Description

TITLE ALL-TERRAIN SKATEBOARDS

FIELD OF THE INVENTION

The present invention relates to all-terrain skateboards.

BACKGROUND OF THE INVENTION

In conventional skateboards, a total of four wheels are arranged with one pair at the front and one pair at the back. All wheels are of very small diameter so as to fit under the deck with each pair possessing a single axle mounted on an oblique pivot, providing steering via the inside wheels moving in toward each other when the rider shifts weight onto that side, and the outside wheels moving away from each other on the unweighted side of the board. Steering is thus provided by all four wheels at once.

The pitfalls of conventional skateboard design are that the small wheels are extremely sensitive to surface irregularities, making them impractical and dangerous to use on anything other than very smooth surfaces. Attempts have been made to overcome such problems by making skateboards with larger wheels. However, larger wheels result in either a higher deck (creating instability) or a much wider structure (with the larger wheels extended out past the edge of the deck such as in 'mountainboards') which makes the board cumbersome and sluggish. The traditional skateboard layout has therefore been restricted to relatively smooth surfaces since its inception.

In an attempt to try and break away from traditional skateboard limitations, various designs have been proposed over the years such as those by Barachet and Kroher. Barachet proposed a two wheeled skateboard with both wheels aligned along a central axis (in-line), like a scooter. The design included a self-steering front wheel, fixed rear wheel and two-part deck, the first part for the front foot between the two wheels and the second part for the rear foot behind the rear wheel.

Barachet' s design included a front wheel held by a fork with a pivot point forward of the middle of the front wheel. By leaning to one side of the board, a front pivot allows the front wheel to turn in the appropriate direction, steering the board. It has been found that in Barachet whilst the front wheel does turn, the Barachet type of device is extremely unstable and very difficult to ride.

A variation of Barachet' s design is found in the German Grassboards developed by Kroher. Kroher made only two changes to Barachet' s design, these being that the front wheel pivot point is horizontally in-line with the axle (better than Barachet but still not providing stability) and the single rear wheel is replaced by two wheels side by side, a small distance apart. It is readily apparent that the dual rear wheels have replaced the single wheel to try and provide some stability to the board in an attempt to make it easier to ride. However, in requiring the lateral stability provided by the dual rear wheels, the smooth transitional side to side turning characteristic theoretically offered by an in-line two-wheeled board is lost.

Finally, in Australian Patent 750255 in the name of the present applicant, there is described and claimed a skateboard provided with a front fork pivot point lower than the front wheel axle (as well as in front of the axle) which provides stability as a result of a convex arc created by the front wheel as it is swung through its turning angle. The application of a rider's weight therefore automatically centers and straightens the front wheel to the top of the arc, creating stability and control. The entire disclosure of Australian Patent 750255 is incorporated herein by reference

However, there are limitations to the low, forward mounted pivot point of the skateboard of Australian Patent 750255. For example, in areas of uneven ground it has been found that ground clearance problems are encountered.

SUMMARY OF THE PRESENT INVENTION

In accordance with one aspect of the present invention there is provided an in-line all- terrain skateboard comprising a longitudinally extending frame locating aligned wheels and one of the wheels being a forwardmost steering wheel, characterized in that the forwardmost steering wheel has a centre comprising a hub, and a curved cross-bar means extends from the hub on either side of the forwardmost steering wheel, the forwardmost steering wheel being arranged to traverse the cross-bar means in response to a weight shift of a rider so as to steer the skateboard.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described, by way of example, with reference to the accompanying drawings, in which :

FIGURE 1 is an example of one embodiment of the present invention, it being a side view of a skateboard in accordance with the present invention showing a front wheel 1, a rear wheel 2, a middle deck 3, a curved cross-bar 4 extending from one side of the frame to the other and through a wheel hub 5, a linear bearing assembly carriage 6 and a front frame 8;

FIGURE 2 is an example of the same embodiment shown in Figure 1 , it being a top view showing the front wheel 1, the rear wheel 2, the middle deck 3, the curved crossbar 4 extending from one side of the frame to the other and through the wheel hub 5, the linear bearing assembly carriage 6, a front wheel travel arc 7, the front frame 8 and an apparent pivot point for the front wheel travel arc 9;

FIGURE 3 is an example of the same embodiment shown in Figures 1 and 2 being a front view of the front wheel and frame assembly showing the front wheel 1, the curved cross-bar 4 extending from one side of the frame to the other and through the wheel hub 5, the linear bearing assembly carriage 6, the front wheel travel arc 7, the front frame 8 and the apparent pivot point for the front wheel travel arc 9; and

FIGURE 4 is an example of the same embodiment shown in Figures 1 , 2 and 3 , being a closer perspective view of the linear bearing carriage assembly 6 showing a short section of the curved cross-bar 4, the linear bearing assembly carriage 6, bearing support lugs 10, bearing insert screws 11 and bearings 12.

DESCRIPTION OF THE PREFERRED EMBODIMENT

With a skateboard in accordance with the present invention, it has been found that problems inherent in a low, forward mounted pivot point are reduced. The design of the present invention utilizes the principle of the front wheel 1 drawing a convex arc created as it swings through its turning angle. Application of a rider's weight automatically centres and straightens the front wheel to the top of the arc (and at this point the frame rests at its lowest point), creating stability and control. However, instead of requiring the wheel 1 to be mounted to a swingarm which pivots in front of the front wheel and below axle height, the skateboard of the present invention uses a convex curved rectangular or square section cross-bar 4 through the middle of the wheel hub 5. The bar 4 extends across the frame from one side to the other and the wheel 1 slides backwards and forwards across the curved bar 4 in the same way as a curved linear bearing system works. With this simple design, a swingarm is no longer required, nor a front, low mounted pivot point so at least some design limitations inherent in the skateboard of Australian Patent 750255 are overcome in a much lighter and smaller system. However, the positive points of stability and ease of riding are maintained in the skateboard of the present invention.

To ensure the front wheel of the skateboard of the present invention glides easily across the curved cross-bar 4 it is preferred to use a well designed, good quality curved linear bearing system. There is a varying range of curved lineal bearing designs that can suit the application but the version described herein and used as an example utilizes two carriages 6 (one on each side of the wheel hub) each containing four skate bearings with each bearing rolling a respective side of the bar 4.

The curved lineal bearing system of the skateboard of the present invention must also be able to glide freely across the curved bar 4 in response to a rider's weight shift. Therefore, running skate bearings backwards and forwards along the curved bar 4 offers a good combination of free movement and durability.

Another option, instead of a continuous curved bar 4 running through the hub 5, is to have two separate curved bars out from each side of the hub 5, running through static carriages on each side of the frame. This follows exactly the same principles and overall curve arc and has the advantage of being able to use standard hubs. However, the disadvantage is that the curved bars project outside of the frame on one side when turning.

Thus, the present invention provides a self-steering, in-line, two-wheeled, all-terrain skateboard that can operate on a wide range of surface conditions ranging from smooth asphalt/bitumen to grass and dirt.

Just as the front wheel of a skateboard according to the present invention is self-steering, in another aspect of the present invention the rear wheel can also pivot in a similar manner to the front wheel using a similar arrangement should a tighter turning radius be required.

hi the following description of the embodiments shown in the accompanying drawings like reference numerals denote like parts.

In Figures 1 to 3 of the accompanying drawings, there is shown an in-line two-wheeled skateboard with a curved cross-bar 4 extending from one side of a frame 8 to the other and through a wheel hub 5 of a wheel 1, the hub 5 being attached to and being arranged to rotate with the wheel 1. A linear bearing assembly carriage 6 is attached to each side of the hub 5, which is laced to the front wheel 1. When a rider stands on a deck 3 and leans to one side, the complete assembly of the wheel 1, the hub 5 and the bearing assembly carriages 6 all slide across the curved cross-bar 4 towards the opposite side that the rider leans. If the rider leans the other way, the complete assembly will in response slide back around the curved cross-bar towards the other side. If the rider stands straight upright without leaning, the complete assembly will move to the middle position of the cross-bar 4, being the highest point of the arc (with the frame at its lowest level).

As shown in Figure 4 each bearing assembly carriage 6 (on each side of the hub 5) comprises four bearings 12 (one bearing 12 per side of a four sided rectangular or square section curved cross-bar 4) and these bearings roll across the bar with minimal friction. Rectangular or square section cross-bars are typical examples that work well in the present invention although any geometry that appropriately matches the bearings can be used, including even concave sides.

The cross-bar 4 has a constant two dimensional radius curved shape.

As can bee seen in Figure 2 the cross-bar 4 has a curved shape in plan with a concave side facing forwardly and a convex side facing rearwardly.

Further, as can be seen in Figure 3, the cross-bar 4 has a curved shape in front view with a concave side facing downwardly and a convex side facing upwardly

The orientation of the cross-bar 4 is achieved by tilting the cross-bar 4 upwardly adjacent a mid point thereof.

In essence, the skateboard of the present invention responds to a rider in similar manner to the swingarm system of Australian Patent 750255. However, the skateboard of the present invention can do this without the weight of a swingarm and a forward, low mounted frame section to hold the pivot point of the swingarm. This results in a lighter, smaller system which is of great advantage to a rider, particularly in off-road riding conditions.

Modifications and variations as would be apparent to a skilled addressee are deemed to be within the scope of the present invention.

Claims

1. An in-line all-terrain skateboard comprising a longitudinally extending frame locating aligned wheels, one of the wheels being a forwardmost steering wheel, characterized in that the forwardmost steering wheel has a centre comprising a hub, and a curved cross-bar means extends from the hub on either side of the forwardmost steering wheel, the forwardmost steering wheel being arranged to traverse the cross-bar means in response to a weight shift of a rider so as to steer the skateboard.

2. An in-line all-terrain skateboard according to claim 1, characterised in that the curved cross-bar means comprises a single curved cross-bar extending through the hub.

3. An in-line all-terrain skateboard according to claim 1 or 2, characterised in that the cross-bar means extends between members of the frame.

4. An in-line all-terrain skateboard according to any one of the preceding claims, characterised in that the cross-bar means is mounted in bearing assembly means mounted to the hub.

5. An in-line all-terrain skateboard according to claim 4, characterised in that the bearing assembly means comprises linear bearing assembly carriages mounted on respective sides of the hub.

6. An in-line all-terrain skateboard according to claim 5, characterised in that the curved cross-bar has a rectangular or square cross-section and respective bearings in each bearing assembly carriage engage with sides of the curved cross-bar.

7. An in-line all-terrain skateboard according to according to any one of the preceding claims, characterised in that the curved cross-bar is curved in two dimensions and has a convex side and a concave side and opposed ends.

8. An in-line all-terrain skateboard according to claim 7, characterised in that in plan view the concave side of the curved-cross bar faces forwardly whilst the convex side faces rearwardly.

9. An in-line all-terrain skateboard according to claim 7 or 8, characterised in that in front view the curved cross-bar has the convex side facing upwardly and the concave side facing downwardly.

10. An in-line all-terrain skateboard according to claim 8 or 9, characterised in that the cross-bar is tilted upwards about the opposed ends so that a highest part of the curve is located at the middle of the cross-bar.

11. An in-line all-terrain skateboard according to according to any one of claims 7 to 10, characterised in that the curved cross-bar has a constant two dimensional radius curved shape.

12. An in-line all-terrain skateboard according to according to any one of the preceding claims, characterised in that the skateboard has two wheels in the form of the forwardmost steering wheel and a rear wheel.

13. An in-line all-terrain skateboard according to any one of the preceding claims, characterised in that a trailing rearward wheel is non-pivotally connected to the frame.

14. An in-line all-terrain skateboard according to according to any one of the preceding claims, characterised in that a deck is supported by the frame to provide a mounting for both feet of a rider.