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. The locomotive was notable for being ALCO's most powerful diesel-electric locomotive and, at the time, the most powerful diesel locomotive ever built, being surpassed by the 6,600-horsepower (4,922-kilowatt) EMD DDA40X in April 1969.