The Alco S-6 (specification DL 430) was a series of diesel-electric switcher locomotives built by the American Locomotive Co. of Schenectady, New York; 126 units in total were built between May 1955 and December 1960.
The S-6 was an improved version and visually indistinguishable from the preceding model S-5; the S-6 used an ALCO 251A or 251B prime mover rated at 900 horsepower (670 kW), and rode on two-axle AAR trucks, giving a B-B wheel arrangement. ALCO produced a cow-calf variant for the Oliver Iron Mining Company designated SB-8/SSB-9.
As of 2025, several S6 locomotives remain operating at tourist railroads and industrial yards across the United States, Canada, and Mexico.
Trivia[]
- In Back to the Future Part III (1990), two S-6 locomotives, #7/11 (hard to determine) and #9 of the Ventura County Railway, infamously destroyed the DeLorean time machine when it returned to 1985. After filming Back to the Future Part III, the three S-6 locomotives continued their service and were sold to the Fillmore and Western Railway where they reside today.
- Besides Back to the Future Part III, they also appear in the films "Who's That Girl?" (1987) and "Ghost Dad" (1990), and they even wear the same colors from Back to the Future Part III.
- The Alco S6 was the sixth model of switcher series the company produced and debuted in 1955 and built until 1960.
Gallery[]
#9 destroying the Delorean in Back to the Future Part III (1990)
#9 (leading) and #7/11 (trailing) destroying the Delorean in Back to the Future Part III (1990)
A BTTF III S-6 diesel in Who's That Girl? (1987)
A BTTF III S-6 diesel in Ghost Dad (1990)
SP No. 1231 at El Centro, California, in 1970.
