The Guigan Transmission technology is protected by a worldwide patent application (PCT/FR2017000174) and later French patent applications.


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OPPERTUS will produce a range of specific gears and transmissions, and will license the technology to selected companies worldwide.

Basically, what we have found is a way to build a gear with a continuously variable diameter.


The main features

  • The number of teeth is not necessarily an integer, and the transmission ratio is varying continuously.
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  • In order to allow the transmission of high powers, the transmission is not using friction as in the prior art, but gears and therefore without possible slipping.
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  • The range of transmission ratios is virtually unlimited.
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  • The transmission ratio may vary automatically as a function of the resistive torque, in real time.
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  • It is possible to have a transition from forward to reverse by a transmission ratio which is zero in one direction and therefore infinite in the other. The device may serve as both as a clutch and as a real energy recovery brake, both wear-free.
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  • The transmission provides excellent performance, which should help manufacturers to more easily achieve the legal pollution thresholds.
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  • The transmission has a very small footprint and a very low weight.
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  • It allows a great simplicity of design, a great rusticity and a low manufacturing cost.

There is of course neither acyclism nor loss of contact between the primary and secondary shafts.


IMPORTANT, this technology enables modifying the ring diameter of a planetary gear train, which enables varying the transmission ratio from positive to negative values, passing by very high or very low values!


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This has important consequences, as a planetary gear train may be have the following functions.

  • a continuously variable transmission;
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  • the same with a whole set of continuously variable reverse ratios;
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  • the same which also works as a clutch;
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  • the same with also works as a very powerful kinetic energy recovery system (as powerful as a disc brake!), which is connected to the ring gear and enters into action when the transmission ratio becomes close to zero;
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  • a hybrid energy transmission, adding the power of two engines, one of them being connected to the planets carrier and the other one to the ring gear;
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  • and a very large of other combinations...
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Some applications

  • All types of engines are concerned, of all powers, from toys to cargo ships and mineral crushers, to cycles, cars and trucks.
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  • Electric motors can be downsized without the risk of overload due to increase of the resistive torque (start, overload, etc.) or overspeed, since the gear ratio automatically adapts. In fact, the necessary torque at start-up is automatically multiplied.
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  • The device makes it possible to combine in parallel engines of different types (hybrid vehicles and electrically powered bicycles, for example).
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  • Electric generators are also an important market (alternators, wind turbines, will always turn at the most efficient speed, etc.).
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  • Finally, braking energy recovery becomes possible even in the case of very strong braking. Braking no longer produces any dust.
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