1926 "snowmobile" could pull a 20-ton load

In the 1920s, Fordson tractors were converted to winter use by adding screw propulsion via large cylinders. The result was a "snowmobile" - dubbed the Snow Motor or Snow Devil. The 11-minute (silent) video shows impressive performance, and not just "for its time." The last portion of the video shows the screw propulsion mounted on an automobile rather than a tractor.

Found at Live Leak, via Reddit discussion board.