Fallbrook Technologies NuVinci bicycle CVT
Fallbrook Technologies' NuVinci CVT on bicycle. The company believes the design can be scaled-up to both automotive and utility-size wind turbine generators.

Pedaling NuVinci

Fallbrook Technologies' Bill Klehm discusses his firm's new continuously variable transmission

By Bill Moore

As amazing as it may sound, Leonardo Da Vinci -- yep, the "Da Vinci Code" guy -- was messing about with the idea for a continuously variable transmission back in 1490.


Talk about a guy who was way ahead of his time.... or maybe everyone else was simply too far behind him. Just as intriguing, a drawing turned up not long ago that some claim is a sketch he made over 500 years ago of what looks like a modern, safety bicycle, which is sort of ironic, as you'll soon appreciate.

Taking their cue from the great Renaissance master, a San Diego company has set out to see Da Vinci's vision finally blossom, starting with the bicycle/light electric vehicle (LEV) sector and expanding outward and upward from there.

That company is Fallbrook Technologies and its president is Bill Klehm, once-upon-a-time with Ford. Now he and his year-old company are out pedaling, in both senses of the word, their new CVT design, which they say is more efficient and less complicated that previous or current designs like those used in the ground-breaking Toyota Prius and Ford Escape gasoline-electric hybrids.

Klehm explained that unlike conventional transmissions -- both manual and automatic -- which have fixed gear ratios, a CVT has an infinite number of ratio possibilities. He pointed out that in a conventional four-speed transmission, every time you shift between gears, there are energy losses as the engine has to slow down and then rev back up. A CVT allows the engine to avoid those losses.

"CVT enables you to seamlessly shift from ratio ranges. Instead of having four distinct gears, literally you have a million gears or a million shift points because the transmission is constantly keeping up with how that motor, of all shapes and sizes, actually wants to run".

He pointed out that for the best efficiency and lowest harmful emissions, you want to keep an internal combustion engine (ICE) in its "sweet spot".

The same applies, but to a somewhat lesser degree, to electric motors under load. They too will tend to stall but before doing so will wastefully draw lots of current.



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