Imagine having your engine speed up while maintaining a crawl on a steep decline. 

 Allison Transmissions Inc. (found behind the Duramax) has just signed a deal with a British company Torotrak. Torotrak specializes in CVT and IVT transmissions. Instead of using multiple gear ratios the IVT is torque controlled.

Snowmobiles and Ag equipment use CVTs. Two variable pulleys are connected with a belt or chain.

An IVT is similar but instead it uses steel discs (blue in the picture) to connect the the drive (green) and free wheeling wheels (yellow). The yellow thing has a gear (not shown) which is connected to a chain that connects to a separate shaft connected to the driveline. It might be better to go their website and look at their videos.

By changing the amount of pressure and angle on the metal discs (with a hydraulic piston) the tires are delivered the desired torque.  A toroid is a donut shape and that is what the metal discs and their fluid flows look like. Similar to a helicopters blades and the shape its air flow makes. The electrical world also uses this donut shape. 

They call this a traction device since the metal discs never actually touch. Instead an oil film is created and power is transferred through the liquid.
Instead of explaining how it works. Lets look at what the claimed benefits include.

1. This is the perfect off road transmission. You pick your speed.
2. Increased mpg
3. Less driveline losses.

If this deal goes well imagine an IVT behind a Duramax.

I wonder how much in common this has to do with an earlier blog about Sonic Diesel Fuel Injection from back in the 1900's? 

Source: http://www.torotrak.com/