EMD's First SD24

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This page was last updated on February 5, 2015.

Back in 1988, when I was doing research on the history of EMD's turbocharger, I ran across a news item in the GM Institute newsletter about the first installation of EMD's turbocharger design being in the on-site power plant during June 1957 to September 1958.

(Read Don Strack's article about UP's turbocharged GP9s, and the road to the first SD24)

Also in 1959, along with the application of both the AiResearch and Elliott turbocharger designs, UP began a turbocharging project in cooperation with EMD. EMD began working on their own turbocharger design in 1956, with the intent of offering a complete line of turbocharged locomotives. The first actual use of the EMD design was on a stand-by, stationary power plant (known as a peaker unit) in early 1958 at EMD's LaGrange factory. By mid-1958 EMD's turbocharger design was ready for an installation on a locomotive for road tests in revenue service. A new six-axle locomotive was built for the purpose in July 1958, with road number 5579 (also its EMD order number). A photo of this locomotive (the first SD24), with the first railroad application of EMD's turbocharger, is shown on p.68 of Kalmbach's "Our GM Scrapbook."

On September 20, 2007, Bill Barber wrote about this on-site power plant at the La Grange plant that was often used as a stationary test site:

The five unit site at the EMD plant was often used for component testing purposed where exposure to long hard service was desired. The test units were often run under overload conditions to simulate extended service for engine components. The power from these engine/ generator sets was used in the plant as needed and any excess power was sold back to Com Ed.

There is another photo of the first SD24 is in Diesel Era's GP20/SD24 book, on page 31, showing EMD 5579 at Ogden, Utah, also in its original configuration.

The configuration of the first SD24 from EMD included a version of a centralized air intake similar to what EMD used on the E8/E9. The larger air intake design addressed UP's findings in 1956-1957 that the E units tended to run hot at high speeds at UP's high altitude mainlines. They also did some testing on a GP9, cutting openings in the hood doors to see if a GP9 unit ran cooler (it did not). Within a year, UP opened up the top of the air intake winterization hatch on its E8s and E9s to increase the flow of cooling air, with its trademark snowshields being the result. They also used snowshields on the AiResearch turbocharged GP9s, which also used a top-mounted air intake.

The larger air intake on the first SD24 was EMD's attempt to satisfy UP's concerns of reduced power across Wyoming's high altitudes, which included documented lack of power and engine overheating. The later production version of the SD24 still used a central air intake, but different from the first SD24.