I had some guy from Switzerland come to our store the about 1 week ago and tried convincing me to put this setup on some of our tractors. He told me it has been around since World War I. They had pictures of it on a old Ford pickup, he said it would loose only 7% of its horsepower and could get 9000 kms to a cord of wood.
Of course theres no way I would consider mounting something like this on a new $300,000 tractor, but it was kinda interesting.