Good Thinking

Roadless wheel concept adjusts to all terrains

Roadless wheel concept adjusts...
Design Engineer Ackeem Ngwenya contemplating the internal structure of his Roadless variable-aspect wheel system (Photo: Ackeem Ngwenya)
Design Engineer Ackeem Ngwenya contemplating the internal structure of his Roadless variable-aspect wheel system (Photo: Ackeem Ngwenya)
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Compliant Roadless support system inside a tire tread (Photo: Ackeem Ngwenya)
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Compliant Roadless support system inside a tire tread (Photo: Ackeem Ngwenya)
A Roadless wheel made of spring steel rods connected to an axle by movable mounts whose adjustment produces varying aspect ratios (Photo: Ackeem Ngwenya)
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A Roadless wheel made of spring steel rods connected to an axle by movable mounts whose adjustment produces varying aspect ratios (Photo: Ackeem Ngwenya)
Rendering of an all-elastic covering on a Roadless wheel support system (Image: Ackeem Ngwenya)
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Rendering of an all-elastic covering on a Roadless wheel support system (Image: Ackeem Ngwenya)
A variety of Roadless wheels developed in the course of clarifying the concept (Photo: Ackeem Ngwenya)
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A variety of Roadless wheels developed in the course of clarifying the concept (Photo: Ackeem Ngwenya)
Design Engineer Ackeem Ngwenya contemplating the internal structure of his Roadless variable-aspect wheel system (Photo: Ackeem Ngwenya)
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Design Engineer Ackeem Ngwenya contemplating the internal structure of his Roadless variable-aspect wheel system (Photo: Ackeem Ngwenya)
Roadless support system with compliant members defining the tread surface (Photo: Ackeem Ngwenya)
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Roadless support system with compliant members defining the tread surface (Photo: Ackeem Ngwenya)
A Roadless support system with a segmented tread attached (Photo: Ackeem Ngwenya)
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A Roadless support system with a segmented tread attached (Photo: Ackeem Ngwenya)
The Roadless wheel concept is based on networks of compliant arches whose shapes vary with the hub separation on the axle (Image: Ackeem Ngwenya)
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The Roadless wheel concept is based on networks of compliant arches whose shapes vary with the hub separation on the axle (Image: Ackeem Ngwenya)
A Roadless wheel adjusted to a variety of aspect ratios (Photo: Ackeem Ngwenya)
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A Roadless wheel adjusted to a variety of aspect ratios (Photo: Ackeem Ngwenya)
Exploded view of a Roadless wheel with a segmented tread (Image: Ackeem Ngwenya)
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Exploded view of a Roadless wheel with a segmented tread (Image: Ackeem Ngwenya)
A Roadless support system adjusted to a narrow aspect ratio inside a tire tread (Photo: Ackeem Ngwenya)
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A Roadless support system adjusted to a narrow aspect ratio inside a tire tread (Photo: Ackeem Ngwenya)
A Roadless support system adjusted to a fat aspect ratio inside a tire tread (Photo: Ackeem Ngwenya)
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A Roadless support system adjusted to a fat aspect ratio inside a tire tread (Photo: Ackeem Ngwenya)
Rendering of the support structure of a Roadless wheel with compliant members forming the tread shape at several aspect ratios (Image: Ackeem Ngwenya)
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Rendering of the support structure of a Roadless wheel with compliant members forming the tread shape at several aspect ratios (Image: Ackeem Ngwenya)
The adjustment mechanism of a Roadless wheel is rather like that of a scissor jack (Image: B. Dodson)
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The adjustment mechanism of a Roadless wheel is rather like that of a scissor jack (Image: B. Dodson)
View gallery - 14 images

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 concept is based on networks of compliant arches whose shapes vary with the hub separation on the axle (Image: Ackeem Ngwenya)
The Roadless wheel concept is based on networks of compliant arches whose shapes vary with the hub separation on the axle (Image: Ackeem Ngwenya)

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.

The adjustment mechanism of a Roadless wheel is rather like that of a scissor jack (Image: B. Dodson)
The adjustment mechanism of a Roadless wheel is rather like that of a scissor jack (Image: B. Dodson)

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).

A Roadless wheel adjusted to a variety of aspect ratios (Photo: Ackeem Ngwenya)
A Roadless wheel adjusted to a variety of aspect ratios (Photo: Ackeem Ngwenya)

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.

A Roadless wheel made of spring steel rods connected to an axle by movable mounts whose adjustment produces varying aspect ratios (Photo: Ackeem Ngwenya)
A Roadless wheel made of spring steel rods connected to an axle by movable mounts whose adjustment produces varying aspect ratios (Photo: Ackeem Ngwenya)

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.

Source: Blackmanfromthesky

Roadless

View gallery - 14 images
22 comments
BigGoofyGuy
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.
Peter Verwey
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.
Dave B13
I like it a lot but vehicle will have to be light and slow. Acceleration & deceleration forces will rack the unsupported elements over.
VirtualGathis
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.
See: http://www.michelintweel.com/ http://www.gizmag.com/reinventing-the-wheel--the-airless-tire/10398/
Slowburn
I don't see it making a smooth rolling tire.
Robert Meurant
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?
Jay Gatto
It is an idea. One that will, unfortunately, not transmit torque.
Siegfried Gust
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.
grtbluyonder
Very clever concept. Now it's time for the materials research which will be a major challenge.
Mirmillion
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.