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In the 1920s the Armstead Snow Motor was developed. When this was used to convert a Fordson tractor into a screw-propelled vehicle with a single pair of cylinders, the combination became known as the Fordson Snow Devil.

Steering was effected by having each cylinder receive power from a separate clutch which, depending on the position of the steering gear, engages and disengages; this results in a vehicle that is relatively
maneuverable. The promotional film shows the Armstead snow motor hauling 20 tons of logs.


http://en.wikipedia.org/wiki/Screw-propelled_vehicle

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