Autonomous Motor Unit - UMA

Afew years ago, Franco Sbarro presented the Orbital Wheel, an ingenious hubless wheel. At the 2003 Geneva Motor Show, the famous Swiss inventor reinvented the wheel for a second time, presenting the Autonomous Motor Wheel or Autonomous Motor Unit.

Engine, gearbox, transmission, brakes, exhaust, radiator, suspension: everything is inside the wheel (photo François Busson)

Franco Sbarro reinvents the wheel for a second time

The principle is simple: as the diameter of wheels has increased over the last few years, why not use the space in the center of the rim to house the engine, thus saving space in the passenger compartment? The transition from an idea to its concrete realization is always difficult. So, with the collaboration of rim manufacturer OZ, Franco Sbarro worked on the concept and came up with this prototype of an autonomous driving wheel. I won't go into more detail on the wheel itself, as I don't have the technical skills or precise information on this invention. The more curious can try to understand the mechanism by looking at the photo below of the open wheel revealing the original Yamaha motorcycle engine, developing 160 hp. The complete wheel includes motor, radiator, brakes, battery and 3-liter fuel tank. The whole unit is therefore totally independent.

The Sbarro stand at Geneva 2003, with the three UMA prototypes

Three application prototypes

To illustrate the many possible applications, three vehicles (with two, three and four wheels) were presented at the Geneva Motor Show in March 2003.

UMA1 - bike (Photo Sbarro)

UMA1 - two wheels

The 2-wheel prototype (UMA1) is the one that most impressed visitors to the Geneva show: Spartan comfort, with a riding position that doesn't seem very comfortable and a huge rear wheel that can't be very practical when cornering. But these flaws aren't really flaws at all, as this bike isn't intended for everyday use. There are small wheels protruding from the sides to stabilize the machine at a standstill, a single-arm front, a protective bubble and an exhaust that protrudes... from the rim! Sitting fifteen centimetres off the ground, the ride must be sensational as soon as you exceed 30 km/h!

UMA2 - tricycle

UMA2 - tricycle

The tricycle (UMA2) reminds me of those 1950s showcars designed by General Motors, with its rocket-like appearance on wheels, jet-shaped headlights and fins. This science-fiction machine is nothing other than a three-wheeled version of the motorcycle. The autonomous driving wheel is at the rear.

UMA3 - four wheels

UMA3 - four wheels

The 4-wheel prototype (UMA3) clearly demonstrates the space-saving benefits of the Sbarro wheel. The 4-seat interior is free of the engine, providing ample space for a boot, for example. The impression of space is exacerbated here by the absence of doors.

UMA2 (photography Andy Beugger)

Copy ?

At the end of 2008, Michelin presented a system equivalent to the Unité Motrice Autonome, but using an electric motor. Could the inspiration have come from Sbarro? The latter was obviously a little annoyed by this copy, even if he smiles about it. In any case, this concept is far from far-fetched.

In brief
1- Simple, brilliant idea
2- All the mechanics occupy the inside of the wheel
3- Three RAM prototypes presented at Geneva 2003
Main sources
1- Book "Franco Sbarro / Concept car" by Fabian Sbarro