description EMD SD70MAC Overview
The EMD SD70MAC is a six-axle freight diesel-electric locomotive developed by General Motors Electro-Motive Division in the early 1990s. Its defining feature is alternating-current traction: a diesel engine drives an alternator, and traction inverters supply AC motors at the axles, giving the locomotive strong low-speed pulling ability. The model was built for North American heavy-haul railroading and is closely related to the DC-traction SD70M.
help EMD SD70MAC FAQ
When was the EMD SD70MAC introduced?
The SD70MAC was introduced in 1993 by General Motors Electro-Motive Division. It became one of the first mass-produced North American freight locomotives using AC traction.
Why did railroads use AC traction on the SD70MAC?
AC traction motors provide strong low-speed pulling performance and resist overheating during heavy loads. That made the SD70MAC particularly useful on demanding freight routes such as coal trains.
Which railroad first ordered the SD70MAC?
Burlington Northern placed the first production order in 1993. Its initial order covered 350 locomotives numbered 9400 through 9749.
Which locomotive competed with the EMD SD70MAC?
General Electric's AC4400CW was a major contemporary competitor. Both models targeted heavy freight service with six axles and alternating-current traction.
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