ALCO Century 855

Infobox Locomotive
name=ALCO C855
powertype=Diesel-electric

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caption=UP 60, an ALCO C855
gauge=RailGauge|ussg|lk=on
builder=American Locomotive Company (ALCO)
buildmodel=C855
serialnumber=84730–84731 (A units), 84732 (B unit)
deliverydate=July, 1964
primemover=Alco 251C, 2 off
cylindercount=V16, 2 off
poweroutput=convert|5500|hp|abbr=on|lk=on
transmission=AC alternator, DC traction motors
length=86 ft (26.2 m)
fuelc
convert|6000|usgal|abbr=on|lk=on
weight=convert|551400|lb|t|1|abbr=on|lk=on
totalproduction=3 (two A units, one B unit) "Note: the stats given in this table pertain to cab unit")
locale=North America
railroad=Union Pacific Railroad
roadnumber=60–61, 60B
disposition=All scrappedThe ALCO Century 855 was ALCO's most powerful diesel-electric locomotive and, at the time, the most powerful diesel locomotive ever built. Powered by a pair of ALCO's 251C diesel engines, and rated at 5500 horsepower (4.1 MW), it was ALCO's answer to the EMD DD35 and the GE U50. Wheel arrangement consisted of 8 powered axles arranged B+B-B+B. Only two A units and one B unit were built, all for Union Pacific Railroad, which had requested double-engined locomotives from EMD and GE in order to replace their ageing fleet of gas turbine locomotives. Poor performance led to their early retirement and eventual scrapping by February of 1972.