Centreless wheel

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Orbis centreless wheel

GeoOrbital Wheel for electric bike conversion kit, however the batteries are included in the setup instead being attached to the bike frame reducing steering capability

Volkswagen 'Reset' Convertible Concept with hub motors perpendicular to the surface

Hydraulic or pneumatic Active suspension can make centreless wheels widely used

Orbis Greenwheel with external cover, however an internal cover is needed as well to avoid dirt and dust over their precision mechanical parts

A centreless wheel is a wheel where the force is delivered in the perimeter of the wheel rather than in the centre, there's a variety of centreless wheels with their own characteristics including the hubless wheel, spokeless wheel, orbital wheel and rim-rider.

Centreless wheels can be powered by an electric motor by using the entire wheel as a motor with magnets in the rims or by using a wheel hub motor or belts, however there's also the possibility of using a pistonless rotary engine as a wheel hub motor feed with isothermal compressed air that can be made with bioplastic. This would be lighter compared to an electric motor and lithium-ion battery electric vehicle and also feed with hydrogen combustion. The propulsion can be delivered in different ways, for example with a rack embedded in the rim or with a hollow linear guide in the rim with a clamping system.

The wheels can be hollow or have covers, spokes and have a single or several points of support inside the wheel. The wheel cover is almost mandatory to not expose the precision mechanical elements to dirt, dust and corrosion.

Centreless wheels require less torque and so compared to centred hub wheels they can have more acceleration, more and faster instant torque and also be more energy efficient, and that's because the rotating axis or shaft is not located in the centre of the wheel, that means they face less radius of rotating inertia and so it creates more centrifugal force, an issue that also affects centred hub wheels cars with small wheels or spokes reducing also the weight of the wheel.

Also they can have a more effective braking capacity by facing less radius of centrifugal force to stop. This can increase with the wheel powering source clamped to both sides of the rim as circular guide.

They haven't brought by any major company and so there has not being development but there have been some scientific publications^[1][2] and small companies, however with today's hydraulic or pneumatic active suspension and by using a wheel cover they can replace centred hub wheels. Also there's the possibility of locating the powering force perpendicular to the surface, improving wheel structural integrity and failure and reducing need of wheel structural reinforcement and so weight, on the other hand centreless wheels can use spokes instead of internal points of support to reduce wheel weight further.

The hubless wheel was invented by Franco Sbarro (who has built a variety of working hubless wheel vehicles, including at least two motorcycles and a car, the 1989 Sbarro Osmos), and patented by Globeholding of Geneva.^{[citation needed]}

Advantages[]

They have more traction and faster acceleration and torque because the powering source endures less radius of rotating inertia compared to centred hub wheels.

More effective braking capacity by facing less radius of centrifugal force to stop.

More energy efficient because it requires less torque and so less engine horsepower and energy consumed.

They can have lower centre of mass that increases and cornering when the wheel power source is located perpendicular to the surface.

They can have more climbing performance compared to centred hub wheels for the reasons exposed above.

Less weight compared to centred hub wheels requiring smaller powering system as in the case of a wheel hub motor, gearing and brake equivalent setup.

With appropriate cover they are dust free in contrast hub wheels that usually don't use cover, exposed to the elements and corrosion.

Disadvantages[]

Without active suspension their performance can drastically limited.

For the same wheel diameter they don't keep centrifugal force or angular momentum compared to centred hub wheels, however centreless wheels can have bigger diameter which can reduce this trade-off.

They can warp or break during a collision if they are hollow spokeless wheels or with a single point of traction inside the wheel.

Examples[]

It has been suggested that Hubless wheel in India be merged into this section. (Discuss) Proposed since October 2020.

Tron: Legacy light cycle[]

One real-life example of hubless wheels are those used in the replica Tron: Legacy light cycle. The illuminated, street-legal motorcycle was sold through Hammacher Schlemmer, inspired by the computer-animated vehicle from the 2010 film Tron: Legacy. Designed for casual cruising and slow ride-bys at shows, it is made from a steel frame covered by a fiberglass cowling that replicates the sleek look of its computer-generated imagery counterpart.

Electroluminescent wire strips built into the tire cowlings, wheel rims, and body illuminate the cycle. It is powered by a fuel-injected Suzuki 996 cc (60.8 cu in) 4-stroke engine. Riders lie at a near-horizontal position astride the padded leather seat, with feet on foot pegs that control its 6-speed constant-mesh manual transmission and hands on the handlebars for throttle and braking. The hubless wheels are former truck tires built up then custom-shaped to fit onto one of two counter-rotating rims spinning within each other, providing the broad-tired authenticity of the computer cycles from the movie.^{[citation needed]}

Skatecycle[]

The Skatecycle is a device similar to a caster board but with 9" hubless wheels and a 2-axis twisting axle replacing the function of the casters. The central axle connects the two standing platforms surrounded by 9" polyurethane hubless wheels, giving them the appearance of stirrups. In order to move the unit, the rider rotates their feet inwards and outwards, creating a wave-like motion in the hinged frame and providing propulsion. In recognition of the novel design, the Skatecycle received the Bronze 2010 IDSA IDEA award in the transportation category.^[3]

Zero Bike[]

Another example of a hubless vehicle is the Zero Bike, a lightweight hubless bicycle whose non-functional prototype won an Industrial Design Excellence Award in 1991.^[4] Designed by then-ArtCenter College of Design students Makota Makita and Hiroshi Tsuzaki, it is based on the principle of magnetic superconductivity, also used in high-speed trains that are suspended above rails.

Ujet[]

Ujet^[5] electric scooter is mass produced in Luxembourg since 2018, featuring front and rear orbital wheels connected to a frame with torsion suspension system, and in-wheel electric motor. Such setup is communicated to benefit from minimal energy loss in transmission. In 2019 Ujet won both iF Gold^[6] and Red Dot^[7] awards for its design.

Orbital wheel[]

The orbital wheel was designed in 1989 by Franco Sbarro in France in an attempt to reduce the number of moving parts by removing the center shaft and hub of the wheel and relying on a circular or star-shaped framework inside the wheel to support it instead. The orbital wheel was created by using two circular bearings inserted inside of each other. The inner bearing provides steering, support, and attachment to the frame. The outer bearing consists of a tire with a brake ring also fixed in. Some of the advantages seen by this design are more accurate steering, less weight, and enhanced braking.

See also[]

• Direct drive mechanism
• Monocycle
• Motorcycle wheel

References[]