EMD SD24

The EMD SD24 was a 2,400 hp (1,800 kW) C-C diesel-electric locomotive built by General Motors' Electro-Motive Division of La Grange, Illinois between July 1958 and March 1963. A total of 224 units were built for customers in the United States, comprising 179 regular, cab-equipped locomotives and 45 cabless B units. The latter were built solely for the Union Pacific Railroad.

The SD24 was the first EMD locomotive to be built with an EMD turbocharged diesel engine, sixteen months before the four-axle (B-B) model GP20. Power output was substantially higher than the 1,800 hp (1,340 kW) of the concurrent Roots blower-equipped SD18s with the same engine displacement.

In terms of sales, the SD24 was only a moderate success, and few had long service lives in SD24 configuration (though a few rebuilds are still in operation), but the SD24 was a milestone in EMD locomotive development and the forerunner to today's high-powered six-axle locomotives.