GE Gas Turbine-Electric

General Electric's involvement with gas turbine locomotive development represented one of the most ambitious and unconventional chapters in American railroad motive power history. GE began serious experimentation with gas turbine-electric locomotives in the late 1940s, producing a demonstrator unit that was tested on several railroads before the technology attracted significant interest from the Union Pacific Railroad. Union Pacific, always eager to explore high-powered motive power for its demanding operations across the western United States, became the primary customer for GE's gas turbine-electric locomotives and ultimately operated the largest fleet of such machines in North American railroad history. The first generation of GE gas turbine-electric locomotives entered Union Pacific service in 1952, with an initial order of ten units followed by subsequent orders that expanded the fleet considerably. These machines were rated at approximately 4,500 horsepower, making them among the most powerful single locomotives then operating in North America. Union Pacific deployed them primarily on its main line through Wyoming and Utah, where their ability to sustain high power output over long distances proved valuable for moving heavy freight trains. A second generation of improved units followed in the late 1950s and into the 1960s, with some examples reportedly producing up to 8,500 horsepower, a figure that dwarfed contemporary diesel-electric locomotives. The gas turbine-electric program ultimately came to an end in the late 1960s as improvements in diesel-electric technology narrowed the power advantage that turbine locomotives had once held. Rising fuel costs also worked against the turbines, which consumed large quantities of Bunker C heavy oil and were less thermally efficient than diesel engines at partial load. Union Pacific retired its gas turbine fleet by approximately 1970, and GE did not pursue further development of the type for railroad applications. Despite their relatively brief operational lifespan, the GE gas turbine-electric locomotives demonstrated that turbine power could be successfully applied to railroad service and influenced subsequent thinking about high-output prime movers in rail transportation.

The GE gas turbine-electric locomotives used an open-cycle gas turbine as their prime mover, in which compressed air was mixed with fuel in a combustion chamber and the resulting hot gases drove a power turbine connected to electric generators. These generators in turn supplied current to traction motors mounted on the axles, following the same general arrangement used in conventional diesel-electric locomotives. The early production units for Union Pacific were arranged in a large, streamlined carbody housing a single turbine powerplant, while later and more powerful variants used paired units or articulated configurations to manage the considerable length and weight of the machinery. The turbines burned Bunker C residual fuel oil, a low-cost heavy fuel that had to be preheated to reduce its viscosity sufficiently for injection into the combustion system, and the locomotives were equipped with small auxiliary diesel engines for startup and switching operations where turbine operation would have been impractical. The principal engineering challenge of the gas turbine-electric was the turbine's characteristic high fuel consumption at less than full power output, a thermodynamic limitation that made the locomotives most economical when operating at or near their rated capacity for sustained periods. The turbine itself operated at extremely high rotational speeds and internal temperatures, which placed demanding requirements on materials and maintenance practices. Noise levels were substantially higher than those of diesel locomotives, a consequence of the turbine's operating characteristics that was noted by crews and communities along the operating routes. Despite these limitations, the power-to-weight ratio and tractive capability of the larger GE gas turbine units compared favorably with anything else available during their years of service.

Models by: Athearn