The EMD SD70 is a series of diesel-electric locomotives produced by Electro-Motive Diesel in response to the GE Dash 9-44CW. Production commenced in late 1992 and since then over 4,000 units have been produced; most of these are the SD70M and SD70MAC models. All locomotives of this series are hood units with C-C trucks.
Prior to the SD70ACe and SD70M-2 models, all SD70 models were delivered with the self-steering HTCR radial truck. The radial truck allows the axles to steer in curves which reduces wear on the wheels and railhead. With the introduction of the SD70ACe and SD70M-2 models, EMD introduced a new bolsterless non-radial HTSC truck as the standard truck for these models in an effort to reduce costs. The HTCR-4 radial truck is still an option.
The SD70 uses the smaller standard cab or spartan cab, common on older 60 Series locomotives, instead of the larger, more modern comfort cab. This makes it hard to distinguish from the nearly-identical SD60, the only difference being the use of the HTCR radial truck instead of the HT-C truck mounted under the SD60. The main spotting feature is the difference in length between the two models – the SD60’s 71 feet, 2 inches vs. the SD70’s 72 feet, 4 inches. The SD70 also rides higher as it’s frame is approximately 1⁄2 inch (13 mm) higher than the SD60’s. This model is equipped with direct current (DC) traction motors, which simplifies the locomotive’s electrical system by obviating the need for computer-controlled inverters (as are required for alternating current (AC) power). It is equipped with the 4,000 horsepower (3,000 kW), 16-cylinder EMD 710 prime mover. One hundred and twenty-two examples of this model locomotive were produced for Norfolk Southern Railway (NS), Conrail, Illinois Central Railroad (IC) and Southern Peru Copper (SPC). Conrail’s assets were split between Norfolk Southern (PRR) and CSX Transportation in 1999, and all 24 of Conrail’s SD70 units went to NS. Other than the CR paint scheme these units were built to NS specifications and numbered (2557 – 2580) in series with their SD70’s.
Production of the standard cab at EMD’s London, Ontario plant ended in 1994. The 24 Conrail SD70s were assembled from kits at Conrail’s (later NS’s) Juniata Shops in Altoona, Pennsylvania, and the IC and SPC SD70s were assembled from kits at Super Steel Schenectady. All SD70s are still in service with Norfolk Southern and Canadian National (CN), which merged Illinois Central in 1999.