Tweel
Encyclopedia
The Tweel is an experimental tire
design developed by the French
tire company Michelin
. The tire uses no air, and therefore cannot burst or become flat. Instead, the Tweel's hub connects to flexible polyurethane
spoke
s which are used to support an outer rim and assume the shock-absorbing role of a traditional tire's pneumatic properties.
, and a series of energy-absorbing polyurethane
spokes. The rectangular spokes can be designed to have a range of stiffnesses, so engineers can control how the Tweel handles loads. The inner hub contains a matrix of deformable plastic structures that flex under load and return to their original shape. By varying the thickness and size of the spokes, Michelin can generate a wide array of ride and handling qualities. The tread can be as specialised as any of today's tires and is replaceable when worn.
The Tweel does have several flaws, however, the worst being vibration. Above 50 mph (80.5 km/h), the Tweel vibrates considerably. That in itself is a big problem, but it also causes two other things: noise and heat. A fast moving Tweel is unpleasantly loud. Also, long-distance driving at high speeds generates more heat than Michelin engineers would like, which might lead to premature failure. The Tweel can also withstand a police 'stinger' spike strip, which would force law enforcement to adapt in order to catch a suspect in a vehicle equipped with Tweels.
s, scooter
s, and other such devices. The iBOT
mobility device and Segway
's Concept Centaur were both introduced with Tweels. Michelin also has additional projects for Tweel on small construction equipment, such as skid steer loaders, for which it seems well-suited.
The first large-scale applications may be in the military where a flat-proof tire would be advantageous. Military testing has indicated that the Tweel deflects mine blasts away from the vehicle better than standard tires and that the Tweel remains mobile even with some of the spokes damaged or missing.
NASA has contracted Michelin to develop a wheel for the next generation Lunar Rover
based on the Tweel. This has resulted in the Lunar Rover Initiative AB Scarab wheels.
Tire
A tire or tyre is a ring-shaped covering that fits around a wheel rim to protect it and enable better vehicle performance by providing a flexible cushion that absorbs shock while keeping the wheel in close contact with the ground...
design developed by the French
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
tire company Michelin
Michelin
Michelin is a tyre manufacturer based in Clermont-Ferrand in the Auvergne région of France. It is one of the two largest tyre manufacturers in the world along with Bridgestone. In addition to the Michelin brand, it also owns the BFGoodrich, Kleber, Riken, Kormoran and Uniroyal tyre brands...
. The tire uses no air, and therefore cannot burst or become flat. Instead, the Tweel's hub connects to flexible polyurethane
Polyurethane
A polyurethane is any polymer composed of a chain of organic units joined by carbamate links. Polyurethane polymers are formed through step-growth polymerization, by reacting a monomer with another monomer in the presence of a catalyst.Polyurethanes are...
spoke
Spoke
A spoke is one of some number of rods radiating from the center of a wheel , connecting the hub with the round traction surface....
s which are used to support an outer rim and assume the shock-absorbing role of a traditional tire's pneumatic properties.
Design
The Tweel consists of a cable-reinforced band of conventional tire rubber with molded tread, a shear band just below the tread that creates a compliant contact patchContact patch
Contact patch is the portion of a vehicle's tire that is in actual contact with the road surface. It is most commonly used in the discussion of pneumatic tires, , where the term is strictly used to describe the portion of the tire’s tread that touches the road surface...
, and a series of energy-absorbing polyurethane
Polyurethane
A polyurethane is any polymer composed of a chain of organic units joined by carbamate links. Polyurethane polymers are formed through step-growth polymerization, by reacting a monomer with another monomer in the presence of a catalyst.Polyurethanes are...
spokes. The rectangular spokes can be designed to have a range of stiffnesses, so engineers can control how the Tweel handles loads. The inner hub contains a matrix of deformable plastic structures that flex under load and return to their original shape. By varying the thickness and size of the spokes, Michelin can generate a wide array of ride and handling qualities. The tread can be as specialised as any of today's tires and is replaceable when worn.
Benefits and drawbacks
Potential benefits of the Tweel include the obvious safety and convenience of never having flat tires. Also, the concept has the potential for true performance gains. Eventually, it may be able to outperform conventional tires since it can be designed to have high lateral strength (for better handling) without a loss in comfort since the design of the spokes allows the vertical and lateral stiffness to be tuned independently. The tread patterns may incorporate holes in the design thus eliminating or significantly reducing aquaplaning. Because only the tread around the circumference would be disposed of when worn as opposed to a whole tire, the environmental impact should be less.The Tweel does have several flaws, however, the worst being vibration. Above 50 mph (80.5 km/h), the Tweel vibrates considerably. That in itself is a big problem, but it also causes two other things: noise and heat. A fast moving Tweel is unpleasantly loud. Also, long-distance driving at high speeds generates more heat than Michelin engineers would like, which might lead to premature failure. The Tweel can also withstand a police 'stinger' spike strip, which would force law enforcement to adapt in order to catch a suspect in a vehicle equipped with Tweels.
Applications
Given the high speed problems with the Tweel, the first commercial applications will be in lower-speed, lower-weight vehicles such as wheelchairWheelchair
A wheelchair is a chair with wheels, designed to be a replacement for walking. The device comes in variations where it is propelled by motors or by the seated occupant turning the rear wheels by hand. Often there are handles behind the seat for someone else to do the pushing...
s, scooter
Scooter (motorcycle)
A scooter is a motorcycle with step-through frame and a platform for the operator's feet. Elements of scooter design have been present in some of the earliest motorcycles, and motorcycles identifiable as scooters have been made from 1914 or earlier...
s, and other such devices. The iBOT
IBOT
The iBOT is a very stable and mobile powered wheelchair developed by Dean Kamen in a partnership between DEKA and Johnson and Johnson's Independence Technology division. It is a medical technology, made to help people with severe mobility problems....
mobility device and Segway
Segway PT
The Segway PT is a two-wheeled, self-balancing transportation machine invented by Dean Kamen. It is produced by Segway Inc. of New Hampshire, USA. The name "Segway" is a homophone of "segue" while "PT" denotes personal transporter....
's Concept Centaur were both introduced with Tweels. Michelin also has additional projects for Tweel on small construction equipment, such as skid steer loaders, for which it seems well-suited.
The first large-scale applications may be in the military where a flat-proof tire would be advantageous. Military testing has indicated that the Tweel deflects mine blasts away from the vehicle better than standard tires and that the Tweel remains mobile even with some of the spokes damaged or missing.
NASA has contracted Michelin to develop a wheel for the next generation Lunar Rover
Lunar rover
The Lunar Roving Vehicle or lunar rover was a battery-powered four-wheeled rover used on the Moon in the last three missions of the American Apollo program during 1971 and 1972...
based on the Tweel. This has resulted in the Lunar Rover Initiative AB Scarab wheels.
See also
- Airless tireAirless tireNon-pneumatic tires , or Airless tires, are tires that are not supported by air pressure. They are used on some small vehicles such as riding lawn mowers and motorized golf carts. They are also used on heavy equipment such as backhoes, which are required to operate on sites such as building...
- Run-flat tire
- Amerityre Zero Pressure Spare Tyre
- Michelin Active Wheel
External links
- Michelin Tweel demonstration video
- Michelin Tweel press releases
- CBS News - Reinventing The Wheel (video WMVWindows Media Video'Windows Media Video is a video compression format for several proprietary codecs developed by Microsoft. The original video format, known as WMV, was originally designed for Internet streaming applications, as a competitor to RealVideo. The other formats, such as WMV Screen and WMV Image, cater...
) - Radical new wheel technology (Gizmag.com.au)
- Rubber Spokes Give Bounce to Airless Safety Tires (May, 1938)