GE U50

The GE U50 emerged from a Union Pacific Railroad initiative in the early 1960s to develop an exceptionally powerful locomotive capable of replacing the railroad's gas turbine fleet. Union Pacific's requirement called for a three-unit consist producing 15,000 horsepower, and General Electric responded alongside EMD and ALCO, which produced the DD35A and Century 855 respectively. GE's answer was a massive twin-engined machine that entered service beginning in October 1963, when the first three units were delivered to Union Pacific. Southern Pacific received three of its own examples in May and June 1964, though that railroad chose not to expand its roster further. Union Pacific, more satisfied with the type's performance, placed additional orders totaling 20 more units, delivered in two batches between July 1964 and August 1965, bringing the Union Pacific fleet to 23 locomotives numbered 31 through 53. Union Pacific's U50s earned the affectionate nickname "U-Boats" from crews, while Southern Pacific's trio, which differed visually from the Union Pacific units by featuring a front cab door and headlights positioned in the hood beneath the front windows, were dubbed "Baby Hueys" after the cartoon character. Southern Pacific's units carried original road numbers 8500 through 8502 before being renumbered twice, eventually settling on 9950 through 9952. The Southern Pacific examples were frequently sidelined and saw limited use over the years. One technically notable Union Pacific unit was number 52, delivered with an experimental Cummins PT fuel system and rated at 5,600 horsepower before being converted to a standard fuel system in October 1966 and rerated to 5,000 horsepower. The U50's service life proved relatively brief. Twenty of Union Pacific's units were retired in 1973 and 1974 and traded back to General Electric in exchange for U30C locomotives, while the final three Union Pacific examples remained on the roster until April 1977. Southern Pacific's three units survived in service until 1977 and were sold for scrap by 1979. No U50 was preserved, leaving the type without any surviving examples.

The U50 was in essence two GE U25B locomotives combined onto a single elongated frame, with each of the two 2,500 horsepower prime movers and its associated generator independently powering the pair of trucks at its respective end of the locomotive, resulting in a total output of 5,000 horsepower. The locomotive rode on four two-axle trucks arranged in linked pairs using span bolsters, producing a B+B-B+B wheel arrangement. Notably, the trucks and bolsters were not newly manufactured components but were instead reclaimed from Union Pacific gas turbine locomotives that GE had built during the 1950s and which were being retired. This reuse of running gear was an economical measure that also influenced the locomotive's overall profile and dimensions. Because the U50 used paired two-axle trucks rather than individual three-axle trucks, it was sometimes incorrectly referred to as the U50D or U50B in later years, designations that were never applied by General Electric or the operating railroads and which do not accurately reflect the locomotive's configuration. The correct model designation remained simply U50, distinguishing it from the later six-axle U50C, which used a C-C arrangement and represented a distinct design. The twin-engine configuration, while delivering impressive horsepower, also introduced the maintenance complexity of managing two complete prime movers within a single unit, a factor that likely contributed to the type's relatively early withdrawal from service.

Models by: Athearn