Reinventing the Wheel

By Motoring Channel Staff - 11/02/2005

As strange as it sounds, French rubber manufacturer Michelin may well have reinvented the wheel, and it could change the way we drive.

The tyre company showcased a potential future for mobility, an integrated tyre and wheel combination missing one ingredient that is usually critical for traditional tyre performance: air.

The company unveiled the first real-world fitments for its revolutionary "Tweel" – which operates entirely without air.

"Major revolutions in mobility may come along only once in a hundred years," said Terry Gettys, president of Michelin's Research and Development Center the US.

"But a new century has dawned and Tweel has proven its potential to transform mobility. Tweel enables us to reach levels of performance that quite simply aren't possible with today's conventional pneumatic technology."

Michelin's Tweel is in production and available as an enhancement for future iBOT mobility systems.

Invented by Dean Kamen, the iBOT mobility device has the ability to climb stairs and navigate uneven terrain, offering mobility freedom impossible with traditional wheelchairs.

Additionally, Segway LLC's Concept Centaur, a prototype that applies self-balancing technology to a four-wheel device, has also been equipped with Tweel to increase its performance potential.

Beyond these first real-world applications, Michelin has additional projects for Tweel on construction skidsteers and a variety of military vehicles to boot. The most intriguing application may be Michelin's early prototype Tweel fitment for passenger cars, and the company released a promising video of Tweel performance on an Audi A4.

"The Tweel automotive application, as demonstrated on the Audi, is definitely a concept, a stretch application with strong future potential," said Gettys.

"Our concentration is to enter the market with lower-speed, lower-weight Tweel applications. What we learn from our early successes will be applied to Tweel fitments for passenger cars and beyond."

Benefits of Tweel:

• The heart of Tweel innovation is its deceptively simple looking hub and spoke design that replaces the need for air pressure while delivering performance previously only available from pneumatic tires.
  
  The flexible spokes are fused with a flexible wheel/tyre that deforms to absorb shock and rebound with unimaginable ease. Without the air needed by conventional tires, Tweel still delivers pneumatic-like performance in weight-carrying capacity, ride comfort, and the ability to "envelope" road hazards (see images above).

• Michelin has also found that it can tune Tweel performances independently of each other, which is a significant change from conventional tires. This means that vertical stiffness (which primarily affects ride comfort) and lateral stiffness (which affects handling and cornering) can both be optimised, pushing the performance envelope in these applications and enabling new performances not possible for current inflated tires.
  
  The Tweel prototype, demonstrated on the Audi A4, is within five percent of the rolling resistance and mass levels of current pneumatic tires. That translates to within one percent of the fuel economy of the OE fitment. Additionally, Michelin has increased the lateral stiffness by a factor of five, making the prototype unusually responsive in its handling.

For Michelin, Tweel is a long-term vision that represents the next step in a long path of industry-changing innovations. Fifty years ago, Michelin invented the radial tyre and there is no question that radial tyre technology will continue as the standard for a long time to come.

Michelin continues to advance the performance of the radial tyre in areas such as rolling resistance, wear life and grip. In the short-term, the lessons learned from Tweel research are being applied to improve those conventional tyre performances.

In the future, the Tweel may reinvent the way that vehicles move. Checking tyre pressure, fixing flats, highway blow-outs and balancing between traction and comfort could all fade into memory.