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EMD's "SD18": Its Third-Cataloged Six-Axle Road-Switcher

Last revised: August 27, 2024

By: Adam Burns

The SD18 was Electro-Motive's third entry in its six-axle, "Special Duty" line.  The model was tailored towards branch line work where its lightweight trucks and six axles could more easily negotiate these secondary corridors.

It was the final normally aspirated variant in the initial series which included the SD7, SD9, SD18, and SD24 (EMD's first turocharged six-motored locomotive).  Its model 567D1 prime mover and 1,800 horsepower offered the greatest - non-turbocharged - output up until that time.

Ironically, the SD18 sold better to foreign lines than domestically with the Korean National Railroad and Central Railway of Brazil acquiring 60 of the 114 units produced.

The locomotive was also EMD's first six-axle model offered with a low, short hood.  The previous SD7 and SD9 were not cataloged with this option although some railroads modified theirs with this configuration. 

Photos

Reserve Mining SD18 #1231, SD9's #1226 and #1229, a rare SD28 (#1233), and an unidentified switcher are seen here in service near Babbitt, Minnesota on May 2, 1970. Jim Jeffery photo. American-Rails.com collection.

History

The SD18 was the third model in EMD's six-motored catalog.  Outwardly, it was nearly identical to the earlier SD9, including the marker lights' location near the edge of the tapered short hood.

In his book, "EMD Locomotives," author Brian Solomon notes the builder - for a brief period between the late 1950s and early 1960s - began listing models by their horsepower ratings.

Why this practice began - and ultimately was discontinued - is unknown although the SD18 was once such model denoting such.  Its model 567D1 prime mover - one of the engine's final variants - boasted 1,800 horsepower and standard Flexicoil trucks.

Spotting Features

The nearly identical SD18 and SD9 are very difficult to differentiate.  Perhaps the easiest spotting feature is the low, short hood - first offered as an option with the SD18.  Two buyers requested this feature, Reserve Mining (pictured above) and Chesapeake & Ohio.

The C&O's units were perhaps the most interesting.  In addition to their low, short hood - the early variants of which featured a slight tapering towards the pilot - Chessie requested theirs be equipped with Trimount trucks from trade-in RSD5s.

The C&O - which had purchased a total of twenty-six such units from Alco in 1952 - was never pleased with these units.  The railroad ultimately wound up with a total of nineteen SD18s.  The big six-axle brutes enjoyed many years in service and several even made it into Chessie System paint before their retirement.

Missabe SD18 #189 and an SDM power another long string of ore jennies through Iron, Minnesota on August 15, 1994. Wade Massie photo.

Reception

Despite sales reaching only 54 units domestically, another 60 were purchased by foreign railroads. Interestingly, this time Southern Pacific - a big buyer of the SD7 and SD9 - was not interested in EMD's latest six-axle locomotive.  However, the railroad would return for future models.

SP was immediately sold on the SD7 and SD9, acquiring some 193 examples - 43 SD7s and another 150 SD9s.   In fact, the railroad tested  demonstrator #990 and ultimately purchased this unit.

The company found these sure-footed locomotives perfectly suited for tackling the steep grades, sharp curves, and light rail found on its many secondary lines in Oregon.

American railroads which purchased the SD18 included:

• Bessemer & Lake Erie ( 851-857)
• Chesapeake & Ohio Railway (1800-1818)
• Chicago & Illinois Midland Railway (60-61)
• Duluth, Missabe & Iron Range (175-193)
• Reserve Mining (1226-1232)

Foreign lines acquired the bulk of production including; Rede Ferroviária Federal, Sociedade Anônima (RFFSA) of Brazil (3401-3445) and the Korea National Railroad (6001-6015).

Data Sheet and Specifications

Production Roster

Total Built = 114

Production of the locomotive had ended by March, 1963. EMD actually had better sales with the SD24 produced at the same time, which sold more than 200 examples (including B units).  This continued a trend across the industry of utilizing increasingly more powerful models in standard road service.

Sources

• Foster, Gerald. A Field Guide To Trains. New York: Houghton Mifflin, 1996.

• Hayden, Bob. Diesel Locomotives: Cyclopedia, Volume 2 (Model Railroader). Milwaukee: Kalmbach Publishing Company, 1980.

• Marre, Louis A. Diesel Locomotives: The First 50 Years, A Guide To Diesels Built Before 1972.  Milwaukee: Kalmbach Publishing Company, 1995.

• Pinkepank, Jerry A. Diesel Spotter's Guide.  Milwaukee: Kalmbach Publishing Company, 1967.

• Schafer, Mike. Vintage Diesel Locomotives. Osceola: MBI Publishing, 1998.

• Solomon, Brian.  EMD Locomotives.  Minneapolis: MBI Publishing Company, 2006.