Inc demonstrated a Fordson Model F converted into a snowmobile, which they dubbed the Snow-Motor. The tractor used bullet-shaped screws instead of wheels or continuous track units to move across the snow. They were used (unsuccessfully) by Richard Byrd's first Antarctic Expedition. Rail conversions In an effort to displace both horses and steam from remote logging railways (bush trams), several enterprising inventors took the Fordson tractor and made modifications to allow them to run on rails. Extra bogies (wheel sets) were added behind and in front of some versions and acted as log bogies, whilst increasing traction on the light rail lines, without increasing weight. Dunedin company Trails Ltd used the Fordson F as a base, adding a reverser, so the tractor could operate either way at the same speeds, and a powered bogie to act as a powered log bogie. Wellington company Nattrass advanced this design, and both companies sales spelled the end to horse-operated bush trams in New Zealand. Nattrass also enjoyed sales in Australia. The last locomotive built by A & G Price, noted steam and diesel locomotive builder was completed in 1970, and used a Fordson Major E1 as a base. Other Ford tractors In the United States Ford reentered the tractor business in 1938 with the Ford N-series tractors. In 1953 this series was replaced by the Ford NAA tractors. Starting around 1961, the U.S. tractor operations and the Ford Ltd U.K. tractor operations, which had been substantially independent although always in close communication, were reorganized into closer integration. After 1964, all tractors made by the Ford companies worldwide carried the Ford brand. In 1986, Ford expanded its tractor business when it purchased the Sperry-New Holland skid-steer loader and hay baler, hay tools and implement company from Sperry Corporation and formed Ford-New Holland which bought out Versatile tractors in 1988. In 1991 Ford sold its tractor division to Fiat with the agreement that they must stop using the Ford name by 2000. In 1999, Fiat removed all Ford identification from their blue tractors and renamed them "New Holland" tractors. Tractor models Fordson Model F Fordson Model N Fordson All-Around (also called Fordson Row Crop) Fordson Major E27N Fordson New Major Fordson Dexta Fordson Power Major Fordson Super Major (called the Ford 5000 in U.S.) Fordson Super Dexta (called the Ford 2000 Diesel in U.S.) Trucks The first heavy duty 2-ton truck ever built by Fordson