BNSF Railway SD70 series SD70ACE No. 8762 pulls a Norfolk Southern train in Indiana.
Jim Wrinn
EMD-built SD70 series locomotives
•YEARS BUILT: 1993-present
•MANUFACTURER: EMD
•OPERATED ON: Most North American Class I freight railroads
•NAMES: SD70, SD70I, SD70M, SD70MAC, SD75I, SD75M, SD70M-2, SD70ACe, SD70ACe-P4, SD70ACe-P6, SD70ACe-T4, and SD70-ACe-T4P4; nicknames: Big Mac, Mac, Grinstein, Flags, Flares
•QUANTITY: 5,587+ as of Dec. 31, 2017
•HORSEPOWER: 4,000, 4,300
•KNOWN FOR: First SD70 model to have A.C. traction motors, which significantly improved adhesion levels, along with higher reliability and reduced maintenance
•STATUS: Most in operation on Class I railroads
How many T4’s,or different names of the same,are on American railroads at the current time?
The SD70 locomotives are also assembled in Brazil at Progress Rail´s plant located in Sete Lagoas, MG. They are designated as model SD70ACeBB, the meter-gauge version of the standard SD70ACe. The locomotive uses 4 bogies because the traction motors of the standard gauge models don´t fit on meter gauge bogies. So, the locomotive is fit with smaller traction motors in more numbers in order to deliver the required power at the rails.I had an opportunity to visit the Progress Rail plant here in Brazil to check SD70´s power electronics design and construction. I found the locomotive is modern, powerful, and comfortable.
The SD70 series seems to be something of an anomaly in the history of locomotive model naming practices. The original SD70, SD70M, SD70I and SD70MAC models were all 4000 hp. As these were all variations on the same basic 4000 hp version of the EMD 710 prime mover, it’s perfectly logical that they’re all identified as SD70s.
The SD70ACe and later models, however, strike me as unusual in that they are essentially an all new design. The frame and body are quite different from earlier SD70s and the 710 prime mover is now rated at 4300 hp. As such, it seems to me that a new model designation would have been appropriate.
The SD70ACe-T4 is also unusual in its model designation. This model has a new truck design, a somewhat different body and the new J series 1010, four-cycle, 4400 hp prime mover. For all these reasons, this model seems to have been particularly deserving of a new designation.
Can anyone out there explain the logic, or lack thereof, as to why EMD insisted on maintaining the SD70 designation for at least three distinctly different locomotive designs?
Thanks!
Allan Manson