The Alco S-5 was a diesel-electric locomotive of the switcher

Switcher

A switcher or shunter is a small railroad locomotive intended not for moving trains over long distances but rather for assembling trains ready for a road locomotive to take over, disassembling a train that has been...

 type rated at 800 hp, that rode on two-axle trucks

Bogie

A bogie is a wheeled wagon or trolley. In mechanics terms, a bogie is a chassis or framework carrying wheels, attached to a vehicle. It can be fixed in place, as on a cargo truck, mounted on a swivel, as on a railway carriage/car or locomotive, or sprung as in the suspension of a caterpillar...

, having a B-B wheel arrangement.

This was Alco's second attempt to build a replacement 251

ALCO 251

The Alco 251 diesel engine was developed by the American Locomotive Company to replace the 244 and 539. The 251 was developed to be used in diesel locomotives, as a marine power plant in ships and as a stationary power generator.-Development:...

-engined switcher to replace the 539

ALCO 539T

The Alco 539T was a diesel prime mover built by the American Locomotive Company. This engine was also used as a stationary powerplant, used in pipeline pumping stations, tugboats and dredges. It has a straight six, four-stroke design in a cast block which produced from . The engine has a bore of...

-engined S-3

ALCO S-1 and S-3

The ALCO S-1 and S-3 were switcher diesel-electric locomotives produced by ALCO and their Canadian subsidiary Montreal Locomotive Works . Basically, the two locomotives differed only in trucks, with the S-1 using ALCO's own Blunt trucks, and the S-3 riding on standard AAR type A switcher trucks...

 and S-4

ALCO S-2 and S-4

The ALCO S2 and S4 were switcher diesel locomotives produced by ALCO and Canadian licensee Montreal Locomotive Works . Basically, the two locomotives differed only in trucks, with the S-2 using ALCO's own Blunt trucks, and the S-4 riding on standard AAR type A switcher trucks. Both were powered...

. Only seven were sold. The demonstrator unit was ALCO specification DL421 and the six production units were ALCO specification DL421A. Alco fitted the 251A engine in its replacement, the S-6

ALCO S-6

The Alco S-6 was a diesel-electric locomotive of the switcher type constructed by ALCO of Schenectady, New York; a total of 126 locomotives were built between May 1955 and December 1960. The S-6 was a development of the earlier S-5; instead of the 800 hp ALCO 251 engine on the previous...

 with power output raised by 100 hp.

External links

• Sarberenyi, Robert. Alco S5, S6, and SSB9 Original Owners.

Original Owners

Railroad	Quantity	Road numbers	Notes
Alco American Locomotive Company The American Locomotive Company, often shortened to ALCO or Alco , was a builder of railroad locomotives in the United States.-Early history:...  (demonstrator)	1	909	to Island Creek Fuel and Transportation Company #102
Boston and Maine Railroad Boston and Maine Railroad The Boston and Maine Corporation , known as the Boston and Maine Railroad until 1964, was the dominant railroad of the northern New England region of the United States for a century...	6	860–865