— Good Thinking
Roadless wheel concept adjusts to all terrains
Design Engineer Ackeem Ngwenya contemplating the internal structure of his Roadless variable-aspect wheel system (Photo: Ackeem Ngwenya)
Graduate student Ackeem Ngwenya has combined the 6000 year-old wheel with modern materials to develop a new type of all-terrain wheel assembly that switches from narrow to wide tread at the turn of a screw. His Roadless wheel system, while envisioned for rural applications in his native Malawi, has the potential to be as big a change to road (and off-road) transport as was the introduction of anti-lock braking.
We've all done it. Before embarking on a long driving trip on smooth-surfaced interstate highways or other roads of national importance, we'll raise the tire pressure to boost the gas mileage a bit. Stuck in the snow, mud, or sand? Let some pressure out of the tires to increase the contact area, while at the same time increasing the chances that the now floppy tire will grab hold. However, the benefits of trying to change the aspect ratio of a tire by simply changing pressure are rather minor, and often associated with a significant loss in tire lifetime.
The Roadless wheel system attempts to throw out the limitations of a pneumatic tire by substituting a tread material wrapped around a pair of rod networks attached by an axle. The rods are adjusted using a mechanism reminiscent of a scissor jack.
When the disks on which the rods are mounted are far apart, the wheel takes the form of a wide tire of small diameter. When the disks are moved close together, the wheel becomes a narrow tire of large diameter. The proximate rods from the two disks are mutually attached to a fixed bearing (light blue circle).
The tread of the wheel must be sufficiently compliant to adapt to the changing aspect ratio of the wheel, so is likely to be some form of elastomer.
Alternately, the wheel can include compliant members that directly form the shape and supporting mechanism for the tread, which can then be as simple as a sheet of rubber.
The video below tells the story of Roadless, and also shows more clearly how it adjusts to varying terrain. There are a host of variations of this basic idea, whose genesis was to make it easier for people living in rural Malawi to more easily deliver their goods to market. It does not seem likely that this concept will stop there.
About the Author
From an early age Brian wanted to become a scientist. He did, earning a Ph.D. in physics and embarking on an R&D career which has recently broken the 40th anniversary. What he didn't expect was that along the way he would become a patent agent, a rocket scientist, a gourmet cook, a biotech entrepreneur, an opera tenor and a science writer.
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I think that is really cool.
Without the tread, I can see it being used on off roads and way off roads like on a distant planet where it could be adjusted to different terrain.
I think it would be great for vehicles without a spare since it seems to not be filled with air.
The main problem I see with this for an off-road application is that the times you need to reduce tyre pressure, and use that extra width, are the same times you need extra clearance. All pictures here show the diameter decreasing as width increases, so the clearance would drop with a width increase and you'd still be stuck, probably more so.
I like it a lot but vehicle will have to be light and slow. Acceleration & deceleration forces will rack the unsupported elements over.
It will be interesting to see if this goes anywhere. One of the reasons pnuematic tires have persisted is that it is difficult to create a material that can flex without failing as often as tires demand yet still offers impact absorption. If he can solve those two problems he will have beaten a number of major companies.
I don't see it making a smooth rolling tire.
A ridiculous throwback with few, if any, real world applications. If successful, this design will require pneumatic suspension to maintain/adjust ride height and open wheel chassis and/or axles that telescope. It will never have high speed capability and as for cornering...forget it. Maybe as a snow machine or bush and swamp buggy.
wouldn't the reduction in circumference lower the vehicle too much and let it get hung on rocks and such when in off road mode?
It is an idea. One that will, unfortunately, not transmit torque.
This is going to run into the problem of what ever elastomeric covering they use for the tread is going to wear down very fast. The types of rubber that allow for a lot of stretching are also the types that show poor wear characteristics.
Very clever concept. Now it's time for the materials research which will be a major challenge.
I predict all the problems insight-fully noted below can and WILL be easily overcome once a few more features and best materials are determined.
An early evolutionary branch of this concept may have been born on the moon for its compact morph-ability and light weight on the Rover,, one of my favorite vehicles.
It would be a lot more practical to use narrow large diameter tires and propel the vehicle with a propeller maximized for low velocities.
I do wonder about the noise such a design would make on a paved road and also if fractured elements would tend to strike by standers. But i can see a huge use of this technology in farm tractors and it is also very similar to one half of some modern transmissions that work with one swelling wheel and one shrinking wheel as well. I can also see this technology in use on off road motorcycles. And just maybe snow covered or ice covered roads could make good use of wheels that work this way.
Intriguing- hope this design sees more development.
Possibly, this could be used on some kind of low powered motorcycle (with very wide forks and rear swingarm) that can adjust between a thin large diameter tyre, and a small fat one that offers high flotation for crossing sand or similar. Not much use for surfaced roads in the developed world, but possibly highly effective in the developing world, where there are few opportunities to travel at even moderate speed.
From many of the comments I deduce that many did not view the video. This applies to extreme rural areas of which we here in the USA have none to compare with Malawi's large number of farmers who would be glad to make the trip via bicycle or multi-wheel version of such. It is difficult to see uses for which we are completely unacquainted.
It does have some engineering challenges but I don't think it is beyond current materials technology. Problematically those very materials may make it far too expensive for the target consumer.
I love ideas for their own sake. It might morph into a game changing product...
Your rubber skin for a tire probably will not work because your demanding too much of it. However; the round typically wire rope shock mount already in production can be modified to be the tread of the wheel. Skew the wire rope as the side plates move closer will not cause them to bulge out and will create a surface. Note smallest diameter no skew circumference least. Highest skew biggest diameter circumference greatest but skew increases the effective angle covered.
Finally braided garden hose pressurized can replace the wire rope for weight, cost, and sound.
I would like to thank Dr. Veritas for directing me to the video. It is only through watching the film that I finally understood the concept and purpose of the innovation.
Yes, there's lots to do still to reach a proof of concept wheel/vehicle, but the idea is inventive and inspirational, exactly what I expect from Gizmag.
I wish the project well.
Looks great till it fill's up with mud and water and rocks Etc.
Interesting concept. On the right vehicle, this also has the potential of acting as sort of a continuously variable transmission (CVT), in effect simplifying the drive train - engine/clutch/variably adjustable wheel.
The reduction in wheel diameter also serves to lower the ratio of the drive train, so when you are riding on a wider tire, you are driving with more force (although a lower speed), as you might have to in less efficient surfaces.
I give full innovation credit and insight driven thinking to Mr Ngwenya for this. Before people begin pointing out flaws, remember that it is not meant to replace the pneumatic tire in all situations. It will have many applications in exactly the situations he meant for it. The project needs to be run through Engineering to replace rods, axle, elastomer, and actuator before it is ready for market but it is quite serviceable for some markets already. Pneumatic tires are not exactly the best choice for jungle use unless you have some means of repairing and inflating them. His wheel, I think, will run quite well on a broken rod until repaired.
I doubt that it will see high speed use, and efforts to raise the speed limit might be expensive and fruitless. This, however, is a design for a specific problem that in my opinion does exactly what it is meant to do.
Looks like this old toy from Galoob (Flex Power Tires)
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