
The EMD SD70 is a series of diesel-electric locomotives produced by the US company Electro-Motive Diesel in response to the GE Dash 9-44CW. Production commenced in late 1992, and since then over 5,700 units have been produced; most of these are the SD70M and SD70MAC models. While the majority of the production was ordered for use in North America, various models of the series have been used worldwide. All locomotives of this series are hood units with C-C trucks, except the SD70ACe-P4 and SD70MACH which have a B1-1B wheel configuration, and the SD70ACe-BB, which has a B-B-B-B wheel arrangement.
Superseding the HT-C truck, a new bolsterless radial HTCR truck was fitted to all EMD SD70s built 1992–2002; in 2003 the non-radial HTSC truck (basically the HTCR made less costly by removing radial components) was made standard on the SD70ACe and SD70M-2 models; the radial HTCR truck remained available as an option.
SD70MAC (1993-2004)-
The SD70MAC uses three phase AC traction motors. Production of the model commenced in 1993, competing against the GE Dash 9-44CW. The majority of SD70MAC models were produced with the 4,000 horsepower (3,000 kW) EMD 710 prime mover while later units are rated at 4,300 horsepower (3,200 kW) and feature EMD SD45-style flared radiators. Starting in 1993, the Alaska Railroad ordered SD70MAC s with head-end power to make them suitable for both freight and passenger service; no other railroad ordered this variant. Due to the Alaska Railroad's satisfaction with these locomotives, they specially ordered additional models after EMD had transitioned production to the SD70ACe.The trucks were replaced with HTCR-4, instead of HTCR-I on former model.
The SD70MAC is no longer produced due to EPA regulations, and was replaced by the SD70ACe in 2004. In total, 1,109 SD70MACs were produced, purchased by Burlington Northern (and its successor, BNSF), Conrail, CSX, Transportación Ferroviaria Mexicana (TFM; units now owned by Kansas City Southern Railway (KCS)), and the Alaska Railroad.