Posted on 01/14/2005 7:01:21 PM PST by aculeus
Engineers at Michelin's US technology centre envision a future in which vehicles ride on what they call the Tweel, a combined tyre and wheel that can never go flat because it contains no air.
The first commercial use of the integrated tyre and wheel assembly will be on the stair-climbing iBOT wheelchair. The Tweel and another airless tyre were on display at this week's Detroit motor show.
Michelin has high expectations for the Tweel project. The concept of a single-piece tyre and wheel assembly is one the company expects to become widespread on passenger cars and, eventually, used on construction equipment and aircraft.
The Tweel offers a number of benefits beyond the attraction of being impervious to nails. The tread will last two to three times as long as radial tyres, Michelin says, and when it does wear thin it can be retreaded. For manufacturers, the Tweel reduces the number of parts, eliminating most of the 23 components of a new tyre as well as the costly air-pressure monitors that will soon be required on new vehicles in the US.
In recent years, manufacturers have devoted an increasing amount of attention to tyres that let motorists continue driving after a puncture, at a reduced speed. Several run-flat designs are available, freeing car makers to eliminate the weight and cost of spare tyres. Michelin, which markets run-flat tyres under the Pax name, took a different approach in developing the Tweel. Its goal: a replacement for traditional tyres designed to function without air.
Mounted on a car, the Tweel is a single unit, though it actually begins as an assembly of four pieces bonded together: the hub, a polyurethane spoke section, a "shear band" surrounding the spokes and the tread band - the rubber layer that wraps around the circumference and touches the road.
While the Tweel's hub functions as it would in a normal wheel, the polyurethane spokes are flexible to help absorb road impacts. The shear band surrounding the spokes takes the place of the air pressure, distributing the load. The tread is similar in appearance to a conventional tyre.
One of the basic shortcomings of a tyre filled with air is that the inflation pressure is distributed equally around the tyre, both up and down (vertically) as well as side-to side (laterally). That property keeps the tyre round but it also means that raising the pressure to improve cornering - increasing lateral stiffness - also adds up-down stiffness, making the ride harsher.
With the Tweel's injection-moulded spokes, those characteristics are no longer linked because of the potential it holds for improving handling response. The spokes can be engineered to give the Tweel five times as much lateral stiffness as current pneumatic tyres.
The Tweel project is in its infancy and only a single set of car Tweels exist. A test-drive in a Tweel-equipped Audi A4 sedan on roads around Michelin's research centre proved to be far less exotic than the construction method or appearance would suggest. The Tweels transmit more of the feel of a coarse road surface than customers would tolerate in a production tyre but that is understandable considering the early stage of development. More important, the steering's response as the driver begins a turn is excellent and large bumps are swallowed up easily by the Tweels and the Audi's unmodified suspension.
There are other negatives: the flexibility, at this stage, contributes to greater friction, though it is within 5 per cent of that generated by a conventional radial tyre. And, so far, the Tweel is no lighter than the tyre and wheel it replaces.
Almost everything else about the Tweel is undetermined at this early stage of development. Michelin's business projections accommodate the possibility that the Tweel may not be an overnight success. This would be nothing new for Michelin: the radial tyre it invented in 1946 was not widely accepted until the 1970s.
Is Al Gore's name on the patent?
Well it sure looks ugly, but I am sure it will perform better. They need to do tests up here in Alaska before they go to market with it though.
They've been available for years for wheelchairs.
Amazing photo. I don't really understand how it can absorb an impact like that and not be bent out of shape, but obviously it works.
Those would be awesome for off road driving...get a stick stuck in one of those and it would beat the crap out of your truck
Interesting. Okay, so let me ask one question: if those things become common place, what are police going to use to handicap a runaway vehicle in those much-televised car chases around Los Angeles? Since these tires don't go flat, spike strips won't be worth a darn.
Good idea... once you get past the dorky name.
I've had other thoughts, too. From time to time.
LVM
Michael Shumacher will campaign these next year!
It does look like some well placed bubble gum, will throw it out of balance.
How'd ja know?
What everyone's missing is this:
"the costly air-pressure monitors that will soon be required on new vehicles in the US."
Get the U.S. federal government out of the marketplace now! Where the hell does it say in the Constitution that the government gets to determine every car has a tire pressure sensor!?!?!?!
I believe that solid rubber tires (non-inflatible, for those of you who live in Rio Linda) were used back in the early 1900's on some trucks in the logging industry in Oregon and Washington where the terrain was not too kind to the tubed air tire. This is not a new invention per se.....maybe just a new design on an old product. However, the solid rubber tire back then was not suitable on the street where a smooth ride was desired. Hope I'm not giving my age away.....any other old geezers out there who remember this???
I think that's in Groucho's copy.
Looks like a reprise of:
Reinventing the Wheel (and the Tire, Too)
http://www.freerepublic.com/focus/f-news/1315785/posts
from just over a week ago.
Lots of technical critique on that thread.
Why not just make a "tar", the combination of a tire and a car. That way when it breaks you just buy a new "tar".
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