ALCO Century 855

The ALCO Century 855 was a model of 5,500 hp (4,101 kW) diesel-electric locomotive built in 1964 by the American Locomotive Company for the Union Pacific Railroad. The locomotive was notable for being ALCO's most powerful diesel-electric locomotive and, at the time, the most powerful diesel locomotive ever built,[1] being surpassed by the 6,600-horsepower (4,922-kilowatt) EMD DDA40X in April 1969.

ALCO Century 855
Union Pacific Railroad 61

Union Pacific Railroad 60B, the only Century 855B built
Type and origin
Power typeDiesel-electric
BuilderAmerican Locomotive Company (ALCO)
Serial number84730–84731 (A units), 84732 (B unit)
ModelDL855, DL856
Total produced3 (two A units, one B unit)
Specifications
Configuration:
​
 • AARB+B-B+B
Gauge4 ft 8+1⁄2 in (1,435 mm)
Length86 ft (26.21 m)
Loco weight551,400 pounds (250,111 kg)
Fuel capacity6,000 US gal (5,000 imp gal; 23,000 L)
Prime moverAlco Dual 251C
Engine typeDual V16 diesel
GeneratorDirect Current GT598 generator
Traction motorsDC traction motors
Cylinders32 (2 x 16)
TransmissionElectric
Performance figures
Power output5,500 hp (4,101 kW)
Career
OperatorsUnion Pacific Railroad
Numbers60–61, 60B
LocaleNorth America
DeliveredJuly 1964
DispositionAll 3 scrapped by 1972
Stats given in this table pertain to cab unit

The Century 855 was designed and built specifically for Union Pacific, which was in need of very high horsepower locomotives for its Overland Route through the Rocky Mountains.[2] Despite its impressive power output, all three examples of the class were scrapped by early 1972 due to mechanical unreliability.

History

Powered by a pair of 16 cylinder ALCO 251C diesel engines, and rated at 5,500 hp (4,101 kW), it was ALCO's answer to the EMD DD35A and the GE U50. The C855 rode on four two-axle trucks, grouped in pairs linked by span bolsters, giving a wheel arrangement of B+B-B+B. The trucks and bolsters were similar to those under UP's earlier turbine locomotives. Only two A units and one B unit were built, all for the Union Pacific Railroad, which had also requested double-engined locomotives from EMD and GE in order to replace the turbines, which had become uneconomical to operate.[1]

Union Pacific also wished to reduce the number of locomotives needed on a consist, to keep in line with their allowable gross weight limit. By consolidating several locomotives into one or two, this allowed them to lower the axle load on the rails, but to stay within the limits placed by the company. They spent their lives in the general freight pool at North Platte; however, constant shutting down due to overheating & poor performance with its twin prime movers led to their early retirement and eventual scrapping by February 1972, after only being in service for less than eight years.[3]

See also

References
  1. "6,000 HP Diesel-Electric for Fast Freight Traffic in USA" Railway Gazette July 3, 1964 pages 547-550
  2. Schafer, Mike (1998). Vintage diesel locomotives. Osceola, WI: Motorbooks International. p. 54. ISBN 0-7603-0507-2. OCLC 38738930.
  3. Lustig, David (March 1, 2023). "Bigger-is-not-necessarily-better-the-Alco-c855-locomotives". Kalmbach. Retrieved March 3, 2023.
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