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Union Pacific operated the largest fleet of gas turbine-electric locomotives (GTELs) of any railroad in the world. The prototype, UP 50 was the first in a series built by General Electric, marketed by the Alco-GE partnership until 1953, for Union Pacific's long-haul cargo services. The prototype was introduced in 1948 and was followed by three series of production locomotives. At one point Union Pacific said the turbines hauled more than 10% of the railroad's freight. Fuel economy was poor, the turbine consumed roughly twice as much fuel as an equally powerful diesel engine. This was initially not a problem, because Union Pacific's turbines were fueled by Bunker C heavy fuel oil. This highly viscous fuel was less expensive than diesel, but difficult to handle. When cold, its consistency is similar to tar or molasses. To solve this problem, a heater was built into the fuel tanks (and later into fuel tenders) to heat the fuel to before being fed into the turbine. Eventually UP switched from Bunker C to modified No. 6 heavy fuel oil, which contained fewer pollutants and solvents. Soot buildup and blade erosion caused by corrosive ash plagued all of the turbines. Changes to the air intake systems on the turbine locomotives improved the air quality reaching the turbine which in turn reduced the wear to the turbine blades and increased the overall running life of the turbine. They were operated into late 1969 and the final two (#s 18, 26) were stored at the Cheyenne roundhouse in operating condition until being retired in Feb 1970. ==Prototype== Union Pacific had long sought the biggest and best locomotives. In the 1930s a pair of steam turbine locomotives were tried but rejected. Before World War II, Union Pacific had been adding diesels to its roster, but none pulled road freight trains. The idea of using four diesels to equal the power of a steam locomotive was unappealing, so the search began for something bigger. General Electric had been building gas turbines for aircraft and proposed using something similar on a locomotive. Union Pacific thought maintenance costs for a locomotive were largely independent of its power, so a smaller number of more powerful locomotives would save money. Union Pacific decided the best way for the turbine locomotives to realize their potential would be to put them on mainline freight trains. The long runs and relatively high speeds would maximize the turbines' efficiency. After Union Pacific expressed interest, GE built a prototype, GE 101, completed in November 1948. After tests in the Northeast during June 1949, it was renumbered UP 50. Painted in Union Pacific Armour Yellow, UP 50 began a round of tests. Union Pacific never took ownership of this locomotive, however. This was one of the few internal combustion locomotives in North America that had a cab at each end. The cabs themselves resembled the FA units being built by Alco-GE at that time. The sides of the locomotive had numerous air intake louvers that could be opened and closed in varying patterns. UP 50 was a carbody unit with a B+B-B+B wheel arrangement – four two-axle trucks, with pairs connected by span bolsters. The turbine produced , of which was available for traction. This power output was more than double that of diesel-electric units of that era. For starting, the unit's auxiliary diesel generator would power a set of windings in the gas turbine's main generator, causing the generator to rotate. The generator's rotation would begin to spin up the turbine, at which point diesel fuel would be used to start combustion. A steam generator would heat and liquefy the turbine's primary fuel supply (heavy Bunker C oil). When the turbine and fuel oil reached their minimum operating temperatures, the fuel to the turbine would be switched from diesel to the primary fuel. This machine weighed and was over long. The turbines were delivered in three main groups after extensive testing of the prototype. Union Pacific intended to use the turbines to replace the famous Big Boys which were about to be retired. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Union Pacific GTELs」の詳細全文を読む スポンサード リンク
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