Last revised: July 20, 2023
By: Adam Burns
The SD70 series was a rebound for Electro-Motive following the issues surrounding its SD50 series. This recovery first began with the SD60 (and its variants) as the model sold more than 1,000 examples allowing EMD to regain some of the reputation that it lost with the SD50.
Although the SD70 could not regain EMD's dominance as the number one locomotive builder, it was still a very successful design with a few thousand different versions of the model operating around the country today (including the SD70M, SD70I, SD70M-2, SD70MAC, and SD70ACe). The SD70 actually hearkens back to the days of the SD40 model and its successes.
It has become so successful that EMD continuous to catalog the locomotive today with the SD70ACe series. Today, thousands of SD70s, and their variants, remains in operation on numerous Class Is around the country. They may not be as common as General Electric models but they are certainly still out there in large numbers.
After relative failures with the SD50 and SD60, EMD finally got back on track with the SD70, which was released in 1992, albeit at the cost of having already lost first place in the market to GE.
The locomotive featured EMD’s 16-cylinder 710G3B engine and was rated at 4,000 horsepower although that was not its biggest selling point.
Learning from the failures of the earlier models EMD upgraded its computer systems and microprocessors to be more easily maintained and introduced perhaps the biggest selling point of all; new, radial trucks.
Featuring the HTCR truck (high-traction, six-axle, radial) it could steer itself into oncoming curves instead of just following the rail which greatly reduced wear to both rail and truck/axle components.
Not surprisingly railroads absolutely loved such a feature, which perhaps more than other reason made the SD70 series so successful.
Many railroads have already stated that a significant reason why they buy EMDs today is just for the steerable trucks, an option GE does not offer with its locomotives. One other particular upgrade with the SD70 series was its vastly improved tractive effort.
At a rating of 175,500 pounds starting and 137,000 pounds continuous the SD70 offers a 40%-60% increase in tractive effort over the SD60 model making it ideal for heavy drag service.
While the original SD70 model was only marginally successful (it only sold over 100 units) later releases, such as the SD70M, SD70MAC, and SD70I were extremely successful. Essentially there is little difference between the designs in terms of overall mechanics and layout.
The SD70M carries the new wide "safety" cab design (also sometimes called a comfort cab it is technically known as the North American Safety Cab) as the original SD70 was built with the Standard Cab purchased only by Norfolk Southern and Illinois Central (NS takes a particular liking to the Standard Cab and carries many in its fleet).
The SD70M has, by far been the most successful SD70 design with over 1,500 built, most of these for Union Pacific who purchased over 1,400 of them!
The SD70I is similar to the SD70M in that its differing
feature involves the cab. The “I” designation refers to the unit having
an isolated cab (EMD calls it the Whisper Cab) from the main prime mover and other mechanical gear. Extremely quiet the feature works quite well although only a few dozen were purchased, all by Canadian National.
Across the industry the most successful SD70 has been the SD70MAC. The MAC carries the same wide-cab design as the SD70M except that it also features AC (alternating current) traction motors.
Different from the traditional DC (direct current) traction motors AC is much more simple, reliable and easier to maintain albeit it costs far more.
This added cost, however, has not deterred railroads and over 1,000 have been built mostly for CSX and BNSF Railway (BNSF’s predecessor Burlington Northern also purchased a few hundred of them).
The newest release of the SD70 line is the SD70ACe (most in the
industry simply call them SD70 "Ace" or "Aces"). Rated at 4,300 hp and
carrying AC traction motors, looking similar to the SD80 and SD90 in
terms of its flared rear radiator grill, the boxy-nosed unit is meant to
comply with the EPA’s latest environmental regulations and since its
debut in 2005 has been fairly successful with a few hundred of the units
built to date.
Lastly there is also the SD70M-2 design, which looks virtually identical to the SD70ACe, and in reality is in virtually every way except for the name.
They are given the “Dash 2” designation simply to differentiate them from the SD70M model but aside from this are identical to their sister SD70ACe. Norfolk Southern is the largest purchaser of the unit (over 100) with Florida East Coast, CN and others chipping in with a few more.
|Entered Production||4/1993 (Norfolk Southern #2501)|
|Years Produced (SD70)||4/1993 - 2/1999|
|Years Produced (SD70M)||7/1992 - 7/2007|
|Years Produced (SD70M-2)||11/2004 - 2/2011|
|Years Produced (SD70I)||7/1995 - 11/1995|
|Years Produced (SD70MAC)||11/1993 - 11/2004|
|Years Produced (SD70ACe)||4/2003 - 5/2015|
|Length (SD70M-2)||74' 2"|
|Height (Top Of Rail To Top Of Cab)||15' 7 ½"|
|Weight (SD70M-2)||390,000 Lbs|
|Fuel Capacity||5000 Gallons|
|Fuel Capacity (SD70M-2)||4900 Gallons|
|Air Compressor Model||WLASC|
|Air Brake Manufacturer||Westinghouse|
|Air Brake Schedule||26L|
|Truck Wheelbase||13' 7"|
|Traction Motors||D90TR (6), GM|
|Traction Motors (SD70MAC)||1TB2630 (6), GM|
|Traction Motors (SD70M-2)||D100 (6), GM|
|Primary Generator||AR20, GM|
|Primary Generator (SD70I)||AR20/CA7, GM|
|Primary Generator (SD70MAC)||TA17/CA7A, GM|
|Primary Generator (SD70M-2)||AR20AB, GM|
|Auxiliary Alternator||A8589 (GM)|
|Wheel Slip Control (SD70I, SD70M)||EM2000es (EMD)|
|Tractive Effort (Starting)||175,500 Lbs at 33%|
|Tractive Effort (Starting)||163,500 Lbs at 28% (SD70M-2)|
|Tractive Effort (Continuous)||137,000 Lbs at 12 mph|
|Tractive Effort (Continuous)||113,000 Lbs at 12 mph (SD70M-2)|
|Top Speed||70 mph|
Total Built = 120
|Owner||Road Number(s)||Quantity||Date Built||Norfolk Southern||2501-2506 (built by GMDD)||916218-1 thru 916218-6||4/1993-5/1993|
|Norfolk Southern||2507-2531 (built by GMDD)||936432-1 thru 936432-25||11/1993-12/1993|
|Norfolk Southern||2532-2556 (built by GMDD)||936433-1 thru 936433-25||8/1994-11/1994|
|Illinois Central||1000-1019 (built by GMDD)||946518-1 thru 946518-20||9/1995-11/1995|
|Illinois Central||1020-1039 (built by Super Steel Schenectady, Inc.)||966727-1 thru 966727-20||2/1999|
|Conrail||2557-2580 (assembled at Conrail's Juniata Locomotive Shop)||976826-1 thru 976826-24||7/1998-11/1998|
Total Built = 1,609
|Owner||Road Number(s)||Serial Number(s)||Builder/Assembler||Completion Date|
|Electro-Motive (Demonstrators)||7000-7002 (became CSX #4675-4677)||926307-1 thru 926307-3||GMDD||7/1992-9/1992|
|Southern Pacific||9800-9824||936438-1 thru 936438-25||GMDD||4/1994-5/1994|
|Electro-Motive (Demonstrators)||7003-7024 (became CSX #4678-4699)||946531-1 thru 946531-22||GMDD||2/1995-4/1995|
|New York, Susquehanna & Western||4050-4054 (Evens)||946536-1 thru 946536-3||GMDD||4/1995-5/1995|
|Union Pacific||4000-4074, 4275-4278||996164-1 thru 996164-79||GMDD||4/2000-11/2000|
|Union Pacific||4279-4284, 4537-4634, 4640-4709, 4523-4536||996168-1 thru 996168-188||GMDD||12/2000-12/2001|
|Union Pacific||4165-4274, 4075-4088||996172-1 thru 996172-124||Bombardier, Inc.||5/2000-12/2000|
|Norfolk Southern||2581-2590||996173-1 thru 996173-10||Juanita Locomotive Shops||10/2000-11/2000|
|Union Pacific||4285-4522||996188-1 thru 996188-238||Bombardier, Inc.||12/2000-12/2001|
|Union Pacific||4119-4164||996190-1 thru 996190-46||Super Steel Schenectady, Inc.||6/2000-11/2000|
|Union Pacific||4089-4118||996192-1 thru 996192-30||GMDD||9/2000-10/2000|
|Union Pacific||4850-5102||20006223-1 thru 20006223-253||Bombardier, Inc.||12/2001-12/2002|
|Union Pacific||4635-4639||20006233-1 thru 20006233-5||GMDD||12/2000-2/2001|
|Union Pacific||4710-4836, 5103-5126, 3874-3970||20006271-1 thru 20006271-248||GMDD||11/2001-9/2003|
|Union Pacific||4837-4849||20006271A-1 thru 20006271A-13||GMDD||11/2002-12/2002|
|Stock||No Number (became Ferrominera Orinoco #1052-1057)||20006271A-14 thru 20006271A-19 (sold on order 200028458)||GMDD||12/2002|
|Stock||No Number (became Union Pacific #3971-3973)||20006271A-20 thru 20006271A-22||GMDD||12/2002|
|Norfolk Southern||2591-2623||20016371-1 thru 20016371-33||GMDD||4/2003-6/2003|
|Union Pacific||3779-3822||L20036559-001 thru L20036559-044||GMDD||5/2004-7/2004|
|Union Pacific||3823-3873||M20036559-001 thru M20036559-051||Bombardier, Inc.||5/2004-8/2004|
|Alaska Railroad||4325-4328 (SD70M-T1)||20056769-1 thru 20056769-4||Electro-Motive Diesel||7/2007|
Total Built = 331
|Owner||Road Numbers||Serial Numbers||Builder||Date Built|
|EMDX||GM74-GM76 (became CEFX #140-142)||20036552-1 thru 20036552-3||GMDD||11/2004-12/2004|
|Canadian National||8000-8024||20046624-1 thru 20046624-25||Electro-Motive Diesel||12/2005-4/2006|
|Norfolk Southern||2649-2700||20046650-1 thru 20046650-52||Electro-Motive Diesel||9/2005-12/2005|
|Norfolk Southern||2701-2778||20056710-1 thru 20056710-78||Electro-Motive Diesel||1/2006-4/2006|
|Florida East Coast||100-103||20056711-1 thru 20056711-4||Electro-Motive Diesel||12/2006|
|Canadian National||8800-8849||20066861-1 thru 20066861-50||7/2007-12/2007|
|Florida East Coast||104-107||20076923-1 thru 20076923-4||Electro-Motive Diesel||9/2008|
|Canadian National||8850-8874||20086893-1 thru 20086893-25||Electro-Motive Diesel||11/2008-12/2008|
|Canadian National||8875-8914||20086152-1 thru 20086152-40||Electro-Motive Diesel||12/2009-3/2010|
|Canadian National||8915-8949||20096294-1 thru 20096294-35||Electro-Motive Diesel||9/2010-1/2011|
|Canadian National||8950-8964||20096294-1 thru 20096294-15||Electro-Motive Diesel||1/2011-2/2011|
Total Built = 26
|Owner||Road Numbers||Serial Numbers||Builder||Completion Date|
|Canadian National||5600-5625||946523-1 thru 946523-26||GMDD||7/1995-11/1995|
Total Built = 1,109
|Owner||Road Numbers||Serial Numbers||Builder||Completion Date|
|Burlington Northern||9401-9402, 9400, 9403-9474||926335-1 thru 926335-75||GMDD||11/1993-9/1994|
|Burlington Northern||9475-9499, 9504-9541||936445-1 thru 936445-63||GMDD||8/1994-3/1995|
|Burlington Northern||9542-9571||946555-1 thru 946555-30||GMDD||11/1994-1/1995|
|Burlington Northern||9572-9710||946565-1 thru 946565-139||GMDD||3/1995-12/1995|
|Burlington Northern Santa Fe||9711-9712||946565-140, 9946565-141||GMDD||1/1996|
|Burlington Northern||9713-9716||946585-1 thru 946585-4||GMDD||6/1995-7/1995|
|Burlington Northern Santa Fe||9717-9775||956615-1 thru 956615-59||GMDD||1/1996-5/1996|
|CSX Transportation||700-724||956636-1 thru 956636-25||GMDD||7/1997-9/1997|
|Burlington Northern Santa Fe||9776-9837||966706-1 thru 966706-62||GMDD||1/1997-8/1997|
|Burlington Northern Santa Fe||8843-8872||968754-1 thru 968754-30||BBD (Bombardier, Inc.)||3/1999-6/1999|
|Burlington Northern Santa Fe||9838-9864||976813-1 thru 976813-27||GMDD||11/1997-12/1997|
|Burlington Northern Santa Fe||9865||976814-1||GMDD||12/1997|
|Burlington Northern Santa Fe||9866-9942||976814-2 thru 976814-78||BBD (Bombardier, Inc.)||4/1998-12/1998|
|Burlington Northern Santa Fe||9995-9999||976814-79 thru 976814-83||BBD (Bombardier, Inc.)||12/1998|
|Burlington Northern Santa Fe||8800-8842||976814-84 thru 976814-126||BBD (Bombardier, Inc.)||12/1998-3/1999|
|Burlington Northern Santa Fe||8873-8876||976814-127 thru 976814-130||BBD (Bombardier, Inc.)||4/1999-5/1999|
|Burlington Northern Santa Fe||8903-8958||976814-131 thru 976814-186||BBD (Bombardier, Inc.)||5/1999-10/1999|
|Burlington Northern Santa Fe||8959-8970||976814-159 thru 976814-198||GMDD||1/2000-2/2000|
|Burlington Northern Santa Fe||8971-8984||976814-199 thru 976814-212||BBD (Bombardier, Inc.)||2/2000-4/2000|
|Burlington Northern Santa Fe||8985-8989||976814-213 thru 976814-217||GMDD||10/2000|
EMD has been very successful with the SD70 despite losing first place to GE and has now given their competitor stiff competition to its similar models the AC4400CW and new Evolution Series™.
Also, for information about Electro-Motive's Special Duty series please refer to the production rosters listed above.
In any event, while GE models are now as common as the SD40 series once was be on the lookout for the SD70 designs, there are plenty of them out there to spot, particularly the unique SD70ACe and SD70M-2s!