ALCO S-6

The ALCO S-6 was a diesel-electric locomotive built by American Locomotive Company (ALCO). It was a low-horsepower (660 hp) switcher locomotive intended primarily for industrial and light switching duties. The S-6 was part of ALCO's "S" series of switchers and utilized ALCO's 6-cylinder, 539T diesel engine. Production ran from 1955 to 1961. Distinguishing features included its low profile and relatively short length compared to other switcher models. Compared to earlier ALCO switchers, the S-6 featured improved electrical components and a more streamlined appearance. Many S-6 locomotives continued in service for decades, often in industrial settings and on short lines.