Airless Tires, New from
Michelin,
Labeled the 'Tweel'.
The all new airless tire from Michelin recently came out into
the publics eye early this year, 2005. Although it appears to be a pretty good
idea and concept, they probably will not be available to the general public
soon. I have looked at the idea and think it is cool, although I don't know what
to think of the center rim selection that you haven't got a choice with. I'm
sure that the police will probably not like the idea because the spike strips
will definitely be ineffective with a set of these on your ride. The ride and
handling seem to be very effective.
Texting and Driving
The first automobile to use air-filled tires was a race car
built by André and Edouard Michelin in the early 1890s. More than a century
later, the French company founded by the Michelin brothers is so identified with
pneumatic tires that its mascot, Bibendum, is a man made of little else.
Now, after decades spent persuading the world to ride on air, the company has
begun work on an innovation that could render the pneumatic tire obsolete.
Engineers at Michelin's American technology center are working on what they call
Tweel, a combined tire and wheel that would not go flat because it contains no
air.
Arriving at a conference room recently to explain the development project, a
research engineer, Bart Thompson, used the Segway Human Transporter that he rode
to the meeting to illustrate his points.
Aboard this self-balancing electric scooter, Thompson whizzed down the hallway
and out to the lobby, pirouetting among the benches and planters to demonstrate
the flexibility of the Tweel.
The Segway would be a small market for Michelin, the world's leading tire maker,
but it is an apt demonstration vehicle for the Tweel. The first commercial use
of the integrated tire and wheel assembly will be on the stair-climbing iBOT
wheelchair, another product developed by Dean Kamen, the Segway's inventor.
Michelin said it would announce another application at the Detroit auto show
next week.
The tire maker has high expectations for the Tweel. The concept of a
single-piece tire and wheel assembly is one that the company expects to spread
to passenger cars and construction equipment and aircraft.
The Tweel offers a number of benefits beyond being impervious to nails in the
road. The tread will last two to three times as long as current radial tires,
Michelin says, and when it does wear thin, it can be retreaded.
For manufacturers, the Tweel offers an opportunity to reduce the number of
parts, eliminating most of the 23 components of a typical new tire as well as
the costly air-pressure monitors that will soon be required on new vehicles in
the United States.
Manufacturers have devoted an increasing amount of attention to tires that allow
motorists to continue driving, at a reduced speed, for at least 100 miles, or
160 kilometers after a puncture. Several such designs are available, providing
peace of mind for travelers and cutting the need for spare tires. Michelin sells
them under the Pax name.
The Tweel, mounted on a car, 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 pavement.
While the Tweel's hub functions as it would in a normal wheel - a rigid piece
that attaches to the axle - the polyurethane spokes are flexible, to help absorb
road impacts. The shear band surrounding the spokes effectively takes the place
of the air pressure, distributing the load. The tread is similar in appearance
to a conventional tire.
One shortcoming of a tire filled with air is that the pressure is distributed
equally around the tire, both up and down as well as side to side. That property
keeps the tire 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-molded spokes, those characteristics are no longer
linked, holding the potential to improve handling response. The spokes can be
engineered to give the Tweel five times as much lateral stiffness as pneumatic
tires without losing ride comfort.
The Tweel is in its infancy - "version 1.0," Thompson said, and only one set of
car Tweels exists. A test drive in a Tweel-equipped Audi A4 sedan on roads
around Michelin's research center proved to be far less exotic than the
construction method or appearance would suggest. The prototype Tweels are noisy,
as Thompson warned they would be, because the spokes vibrate. (Pictures above.)
Almost everything else about the Tweel is undetermined at this early stage of
development, from serious matters like cost to more frivolous questions like the
possibilities of chrome-plating.
Other uses - military vehicles, for example - would come before automobiles, but
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
tire it invented in 1946 was not widely accepted in the United States until the
1970s.
