Union Pacific was the only railroad in the United States to own and operate gas turbine locomotives. The turbine, rather than an internal combustion diesel engine, drove an alternator/generator to supply electricity to electric motors mounted on the axles. Union Pacific's gas turbine fleet totalled 55 locomotives.
The first turbine, No. 50, was built by Alco-GE in 1948 and was tested extensively on UP in 1949. Although it was painted in Union Pacific colors, the railroad never owned No. 50, but it paved the way for the GE turbine fleet which followed. The first ten UP turbines, Nos. 51-60, packing 4,500 horsepower each, were delivered to UP by General Electric in 1952. Fifteen more of these units were ordered in 1954 and numbered 61-75. Thirty units of a larger model, numbered 1-30, were delivered between 1958 and 1961. With a hefty 8,500 horsepower apiece, the last 30 units were the largest locomotives ever built.
The turbine fleet pulled freight trains between Council Bluffs, Iowa, and Ogden, Utah. Although tested on the Salt Lake City to Los Angeles run, their tremendous noise quickly made them unpopular in California. The locomotives were nicknamed "Big Blows" for their deafening jet engine exhaust noise. The huge locomotives, with their big appetite for fuel oil, eventually fell victim to the more efficient diesels, and in 1970 the turbines ran their last miles.
Union Pacific also experimented with a steam turbine in 1939 and a coal-fired turbine in 1962. Neither locomotive however, was successful.
Although Union Pacific never donated any turbines directly to museums, two of the locomotives did survive and now are on public display. No. 18 is at the Illinois Railway Museum in Union, Ill., and No. 26 and 26B are displayed at Union Station in Ogden, Utah.