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EMD "SD70," "SD70MAC, and "SD70M-2"

Last revised: October 27, 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.

Photos

Electro-Motive SD70M demonstrator #7023 test on the Union Pacific; June 19, 1996. Location not listed. American-Rails.com collection.

Development

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.

SD70M

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!

SD70I

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.

SD70MAC

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).

SD70ACe

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.

SD70M-2

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.

Data Sheet and Specifications

Entered Production4/1993 (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
Engine710G3B
Engine (SD70MAC)710G3C-ES
Engine BuilderGM
Horsepower4000
RPM904
Cylinders16
Length74' 0"
Length (SD70M-2)74' 2"
Height (Top Of Rail To Top Of Cab)15' 7 ½"
Width10' 3"
Weight415,000 Lbs
Weight (SD70M-2)390,000 Lbs
Fuel Capacity5000 Gallons
Fuel Capacity (SD70M-2)4900 Gallons
Air CompressorGardner-Denver
Air Compressor ModelWLASC
Air Brake ManufacturerWestinghouse
Air Brake Schedule26L
TrucksC-C
Truck TypeHTCR-II
Truck Wheelbase13' 7"
Wheel Size40"
Traction MotorsD90TR (6), GM
Traction Motors (SD70MAC)1TB2630 (6), GM
Traction Motors (SD70M-2)D100 (6), GM
Primary GeneratorAR20, GM
Primary Generator (SD70I)AR20/CA7, GM
Primary Generator (SD70MAC)TA17/CA7A, GM
Primary Generator (SD70M-2)AR20AB, GM
Auxiliary AlternatorA8589 (GM)
AlternatorCA7A (GM)
Wheel Slip Control (SD70I, SD70M)EM2000es (EMD)
MU (Multiple-Unit)Yes
Dynamic BrakesYes
Gear Ratio70:17
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 Speed70 mph

Production Rosters

SD70

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

SD70M

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

SD70M-2

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

SD70I

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

SD70MAC

Total Built = 1,109

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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!

Sources

  • Foster, Gerald. A Field Guide To Trains. New York: Houghton Mifflin, 1996.
  • Marre, Louis A. and Pinkepank, Jerry A. Contemporary Diesel Spotter's Guide, The: A Comprehensive Reference Manual To Locomotives Since 1972.  Milwaukee: Kalmbach Publishing Company, 1989.
  • Marre, Louis A. Contemporary Diesel Spotter's Guide, The: A Comprehensive Reference Manual To Locomotives Since 1972, Including Rebuilding, Upgrading, And Leasing Programs (2nd Edition).  Milwaukee: Kalmbach Publishing Company, 1995.
  • McDonnell, Greg. Locomotives: The Modern Diesel & Electric Reference, 2nd Edition. Buffalo: Boston Mills Press/Firefly Books, 2015.
  • Solomon, Brian. American Diesel Locomotive, The. Osceola: MBI Publishing, 2000.
  • Solomon, Brian.  EMD Locomotives.  Minneapolis: MBI Publishing Company, 2006.
  • Solomon, Brian.  GE and EMD Locomotives:  The Illustrated History.  Minneapolis:  Voyageur Press, 2014.

SteamLocomotive.com

Wes Barris's SteamLocomotive.com is simply the best web resource on the study of steam locomotives. 

It is difficult to truly articulate just how much material can be found at this website. 

It is quite staggering and a must visit!