EMD SD70M-2

The EMD SD70M-2 emerged as Electro-Motive Diesel's answer to increasingly stringent emissions requirements in North America. When the United States Environmental Protection Agency's Tier 2 diesel emissions standards took effect on January 1, 2005, EMD needed a successor to the SD70M that could meet those new thresholds while retaining the proven characteristics that had made the SD70M so popular, particularly with major Class I railroads. Development of the SD70M-2 thus proceeded alongside the AC-traction SD70ACe, with the two models sharing certain design elements while serving different market segments. The SD70M-2 was aimed at railroads that preferred the relative simplicity and lower maintenance overhead of direct current traction systems. Production of the SD70M-2 ran from 2004 through approximately 2012, with more than 200 units ultimately constructed. The model found its primary customer base among railroads that had already built fleets of DC-traction power and wished to maintain commonality in their operations and maintenance practices. While the SD70M-2 never achieved the enormous production volumes of its predecessor, the SD70M, it served as a competent and reliable option for operators who valued the DC drivetrain philosophy during a period when much of the industry was shifting toward AC traction technology. The SD70M-2 occupies a relatively modest but noteworthy place in the broader SD70 family lineage, representing one of EMD's final efforts to market a high-horsepower, DC-traction six-axle road locomotive in the North American freight market. As the industry continued its broader transition toward AC traction and later toward higher-tier emissions-compliant designs, the SD70M-2 gradually faded from production, leaving the SD70ACe as EMD's primary offering in the heavy road freight segment.

The SD70M-2 is powered by the EMD 710G3B-T2 prime mover, a 16-cylinder version of the long-running 710 engine family tuned to comply with EPA Tier 2 emissions standards while producing 4,000 horsepower. The locomotive rides on C-C trucks and uses direct current traction motors, distinguishing it from the contemporaneous SD70ACe, which employs AC traction technology. Beginning in 2003, EMD standardized the non-radial HTSC truck on both the SD70ACe and SD70M-2 as a cost-reduction measure, replacing the earlier HTCR radial truck that had been standard across the SD70 family since 1992, though the radial truck remained available as an option for purchasers who preferred it. The SD70M-2 shares the wide-nose North American Safety Cab configuration associated with the later SD70M variants, providing crew comfort and visibility improvements over earlier standard-cab designs. The locomotive's use of the 710G3B-T2 engine variant, with its Tier 2 calibration, required engineering adjustments to combustion and fuel management relative to earlier 710-series installations. As a road switcher rated at 4,000 horsepower with a C-C wheel arrangement, the SD70M-2 was well suited to general heavy freight service, offering tractive capability broadly comparable to its SD70M predecessor while meeting the updated regulatory environment under which it was designed to operate.