# Variator as an EV transmission



## skooler (Mar 26, 2011)

Hi All,

Got into a debate earlier about the need for a transmission in an EV

I believe that 2 or 3 forward gears are required in my car.

Got me thinking. I once had a moped which used a variator - a belt would slide up and down a cone shape on the engine side to change the drive ratio. this is shown on the LHS in the picture below.










Any reason why a similar concept wouldn't work in an EV?


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## piotrsko (Dec 9, 2007)

Audi does one in their higher class platforms, but I don't know how common or how available.


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## WarpedOne (Jun 26, 2009)

Audi called it Multitronic. When I last looked they were abandoning it because of poor reliability and very sluggish performance in auto mode.

The proper way of doing a CVT is a planetary CVT with two motors as in Prius or Volt.

One motor can be low-revving high torque motor that moves the car at low speeds, the other can be lower torque and higher revving that moves the car to higher speeds. Such a CVT acts as a rev-adding system. At low speeds only higher-torque motor spins. When it reaches its max rpm, it keeps spinning at this max rpm and the other motor adds its revs.

Buy a Volt, remove the ICE generator and add more batteries


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## frodus (Apr 12, 2008)

I actually drove an Audi A4 FWD for about 3 months before I got my 2007 A4 Quattro.... and apparently all of the FWD A4's (of the b5 generation at least) were CVT. I'm sure other models are as well, but I'll refrain from making assumptions. I do know that it's more maintenance than a STD or regular automatic. It was weird to accelerate and the RPM on the engine just stays the same. Sport shift just moved the belts to predefined points. They're worse for efficiency than regular cut gears on a manual transmission, but not sure about comparison to a normal automatic.


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