|Build date||1969 - 71|
|AAR wheel arr.||C-C|
|Gauge||4 ft 8 1⁄2 in (1,435 mm)|
|Length||79 ft (24.08 m)|
|Prime mover||Dual GE FDL-12|
|Engine type||Diesel engine|
|Power output||5,000 hp (3,700 kW)|
|Safety systems||Leslie S-5T-RF air horn.|
|Career||Union Pacific Railroad|
Produced between November 1969 and November 1971 solely for the Union Pacific; 40 locomotives were constructed as Union Pacific numbers 5000 to 5039. An evolution of the earlier U50 design, the U50C used a pair of three-axle trucks instead of the four two-axle trucks used on the U50. Again, these were reused trucks, this time from the later, 8,500 hp (6,300 kW) GE turbine locomotives.
Development of the U50C was to the same UP specification that produced the EMD DDA40X "Centennial" units—a requirement for a high power locomotive for the railroad's high-speed freight trains. The span-bolster B+B-B+B design was not suited to this service; furthermore, the requirement for power at speed rather than low-speed hauling meant that six powered axles would be sufficient.
The design incorporated extensive weight saving features so as not to overload the three-axle trucks. GE replaced the 16-cylinder prime movers of the U50 with advanced 12-cylinder engines, which were lightweight and shorter. The engines were reversed in orientation compared to the U50, placing the radiator sections at the middle of the locomotive instead of the ends of the carbody. The shorter overall length required a wider radiator section design, similar to that used on the U33B and U33C locomotives.
The U50C was not a successful design. The extreme weight saving measures taken to make the locomotive able to use six axles rather than eight caused numerous problems, especially in the electrical wiring; Aluminum wires instead of the regular copper had been used, which proved prone to overheating. The U50Cs suffered from many serious electrical fires as well as other failures; the UP rewired one unit with copper experimentally and considered having an outside contractor replace the wiring on all the units, but decided that the problems as a whole were too serious. The trucks suffered from stress cracks in the cast frames; the engines frequently developed low oil pressure; the cooling water leaked, and the dynamic brake grids were prone to melting down.
A business downturn in 1976 proved the end of the U50C in service; all were withdrawn, although many were stored in serviceable condition. No return to service occurred, though five were lent out as stationary power generators during a coal miners' strike in early 1978. All were sold for scrap during 1977-1978.
- Morgan, David P. (May 1969). "Traction topics". Modern Railways (Ian Allan Ltd.) XXV (248): p 249.
- Komanesky, John et al. General Electric U50 Roster. Retrieved January 14, 2005.
- Percy, Richard A. Southern Pacific U50. Retrieved January 14, 2005.
- Strack, Don. A History of Union Pacific Dieselization, 1934-1982, Part 4. Retrieved January 14, 2005.
- Strack, Don. All-Time UP Diesel Roster. Retrieved January 14, 2005.
- Strack, Don. Union Pacific GE Dash 8 Locomotives. Retrieved January 14, 2005. Mentions earlier UP GE purchases also.
- Union Pacific Railroad Locomotive Department (1979). Locomotive Diagram Book. Union Pacific Railroad Company.
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