Photograph of McIntosh and Seymour engines at Central Pump Station, Port Arthur, Texas.

([Photograph of McIntosh and Seymour Engines at Central Pump Station]photographJuly 1992; (

accessed February 25, 2024), University of North Texas Libraries, The Portal to Texas History,; crediting Museum of the Gulf Coast.)



McIntosh & Seymour was an American manufacturer of steam and internal combustion engines during the late 19th and early 20th centuries.

The company was founded in 1886, and was based in Auburn, New York. It developed and sold a wide variety of steam engines through the end of the 1800s, and by 1910 had begun to build diesel engines to a design from the Swedish company Aktiebolaget Atlas. It primarily produced large engines for stationary generator and marine applications.


A 6-cylinder McIntosh & Seymour engine on a flat car on a siding at the Cass Mtn. scenic railway in WV, July 2010.

(Hallcp, Public domain, via Wikimedia Commons)



In the 1920s, McIntosh & Seymour was an early builder of diesel engines for use in railroad locomotives, providing an engine to the American Locomotive Company (Alco) for an experimental locomotive. In 1929, Alco purchased McIntosh & Seymour, and operated it as a subsidiary for some time before the name vanished. Under Alco ownership, McIntosh & Seymour designed and built Alco's first production diesel engine, the 531, and later, the 538.

The company's archives are held by the Smithsonian Institution, covering the period from circa 1886-1939.


The ALCO 539 (also known as the McIntosh & Seymour 539) was an inline 6-cylider diesel engine.

With turbocharger it was designated the 539T. An extremely tough engine, and were rated from 660-hp. to 1,000-hp.

(American Locomotive Co., W. Lenheim Collection)


Diesel engines built by the American Locomotive Company (ALCO):


McIntosh & Seymour (Subsidiary)

  • McIntosh & Seymour 531
  • McIntosh & Seymour 538


  • ALCO 539T (also known as the McIntosh & Seymour 539T)
  • ALCO 241
  • ALCO 244
  • ALCO 251


A McIntosh & Seymour Engine, ca. 1893.

(W. Lenheim Collection)

A McIntosh & Seymour engine in use with the US Navy in the 1930s.

(State Archives of North Carolina Raleigh, NC, Public domain, via Wikimedia Commons)


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