EMD SD70 series


The EMD SD70 is a series of diesel-electric locomotives manufactured by Electro-Motive Diesel. This locomotive family is an extension and improvement of the EMD SD60 series. Production commenced in late 1992 and since then over 5,700 units have been produced; most of these are the SD70M, SD70MAC, and SD70ACe models. While the majority of the production was ordered for use in North America, various models of the series have been used worldwide. All locomotives of this series are hood units with C-C trucks, except the SD70ACe-P4 and SD70MACH which have a B1-1B wheel configuration, and the SD70ACe-BB, which has a B+B-B+B wheel arrangement.
Superseding the HT-C truck, a new bolsterless radial HTCR truck was fitted to all EMD SD70s built 1992–2002; in 2003 the non-radial HTSC truck was made standard on the SD70ACe and SD70M-2 models; the radial HTCR truck remained available as an option.

Models

SD70 (1992–1999)

The EMD SD70 has the smaller spartan cab, typical on preceding SD60 models, instead of the larger comfort cab used on later models. Notable differences between the SD70 and SD60 are the radial steering EMD HTCR truck instead of the older HTC truck, and the SD70's overall length of, with the older SD60 being 2 inches shorter. The SD70 also rides higher as its frame is approximately higher than the SD60. This model is equipped with direct current traction motors, which simplifies the locomotive's electrical system by obviating the need for computer-controlled inverters. It is equipped with the, 16-cylinder EMD 710 prime mover. One hundred and twenty-two examples of this model locomotive were produced for Norfolk Southern, Conrail, Illinois Central and Southern Peru Copper Corporation. Conrail's assets were split between Norfolk Southern and CSX 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 in series with Norfolk Southern's already purchased SD70s.
Production of the standard cab at EMD's London, Ontario plant ended in 1999. The 24 Conrail SD70s were assembled from kits at Conrail's Juniata Shops in Altoona, Pennsylvania, while the IC and SPCC SD70s were assembled from kits at Super Steel Schenectady. Most SD70s are still in service with Norfolk Southern and Canadian National, which merged with Illinois Central in 1999. In February 2017, NS began a program to convert its SD70s from DC to AC, which will also have a new wide-nose cab, and several other upgrades. They will be designated as SD70ACC.

SD70M (1992–2004)

The SD70M has a wide nose and a large comfort cab, allowing crew members to ride more comfortably inside of the locomotive than the older standard cab designs. There are two versions of this cab on SD70Ms: the Phase 1 cab, which was first introduced on the SD60M, and the Phase 2 cab, which is a boxier design similar to the original three-piece windscreen on the SD60M, which is shared with the Phase 2 SD90MAC, SD89MAC, and SD80ACe. The Phase 2 cab has a two-piece windscreen like the Phase 1 windscreen but the design of the nose is more boxy, with a taller square midsection for more headroom.
The SD70M is equipped with D90TR DC traction motors and the 710G3B prime mover. They are capable of generating of continuous tractive effort. From late 2001, the SD70M was produced with SD45-style flared radiators allowing for the larger radiator cores needed for split-cooling. Split-cooling is a feature that separates the coolant circuit for the prime mover and the circuit for the air pumps and turbocharger. There are two versions of this radiator: the older version has two large radiator panels on each side, and the newer version has four square panels on each side. This modification was made in response to the enactment of the United States Environmental Protection Agency's Tier 1 environmental regulations. Also the truck was replaced with HTCR-4, instead of HTCR-I on former model.
Production of the SD70M ceased in late 2004 as production of the SD70M-2 model began. A total of 1,609 SD70Ms were produced. Purchasers included New York, Susquehanna & Western, Norfolk Southern and Southern Pacific, but the vast majority were purchased by Union Pacific.
In 2000, an order of SD70Ms made history when Union Pacific ordered 1,000 units. This order was later extended by nearly 500 additional units.
This locomotive model is also built for export, and is still catalogued by EMD. CVG Ferrominera Orinoco has six SD70Ms that were built as an add-on order to UPs FIRE cab equipped SD70Ms. Companhia Vale do Rio Doce in Brazil has ordered 55 of this model for service for the Carajás mine pulling trainloads of iron ore. Since CVRD track is gauged at, a wider bogie, the HTSC2, was designed for these units by EMD.

SD70I (1995)

The SD70I is a version of the SD70 which has been fitted with a cab that is isolated from the frame of the locomotive with rubber gaskets. The isolation reduces noise and vibration from the prime mover. A seam is visible across the nose and on the long hood where the cab connects with the body. 26 examples of this model locomotive were produced, all for Canadian National. The WhisperCab feature was incorporated into some SD70MACs and was standard on both the SD80MAC and SD90/43MAC models.

SD70MAC (1993–2007)

The SD70MAC uses three phase AC traction motors. Production of the model commenced in 1993, competing against the GE AC4400CW. The majority of SD70MAC models were produced with the EMD 710 prime mover while later units are rated at and feature EMD SD45-style flared radiators. Starting in 1993, the Alaska Railroad ordered SD70MACs with head-end power to make them suitable for both freight and passenger service; no other railroad ordered this variant. Due to the Alaska Railroad's satisfaction with these locomotives, they specially ordered additional models after EMD had transitioned production to the SD70ACe.The last order of Alaska Railroad SD70MACs was built/delivered in late 2007. The trucks were replaced with HTCR-4, instead of HTCR-I on former model.
File:CSX Loco No.4761.jpg|thumb|CSX SD70MAC No. 4761 with SD45-style flared radiators
The SD70MAC is no longer produced due to EPA regulations, and was replaced by the SD70ACe in 2004. In total, 1,109 SD70MACs were produced, purchased by Burlington Northern, Conrail, CSX, Transportación Ferroviaria Mexicana, and the Alaska Railroad.

SD70ACe (2004–present)

The SD70ACe is the successor to the SD70MAC with design changes to comply with emission standards. The engine fires with 15% lower internal pressure to improve emissions and features fewer internal components in the inverter. The SD70ACe is equipped with EMD's 16-710-G3C-T2 prime mover, rated at ; later Tier 3 models are rated at, and have a thermal efficiency of almost 36%. They are rated at starting tractive effort and continuous. Braking effort is rated at. Early models featured a bad cab design which was noticed first on CSX as crews reported annoying disturbances such as prime mover noises, traction motors and more. The cab was also known for rattling, leading to the nickname "Thundercabs". As a result, these units are also not approved for leading trains.
In 2012, EMD also built four models known as the SD70ACe-P6. These units, unlike previous SD70ACe's, have one inverter per axle on the trucks, rather than EMD's traditional one inverter per truck design. Four of those were sold to Canadian National Railway and renumbered to CN 8100–8103.
In 2014, BNSF took delivery of 20 SD70ACe-P4 units, numbered 8500 - 8519. This model was designed with a B1-1B wheel arrangement to compete with GE's ES44C4 model, which has an A1A-A1A wheel arrangement. Both wheel arrangements mean that there are only two traction motors per truck instead of three, those being the ones next to the fuel tank. Two SD70ACe-P4 demonstrators began a 5-year lease at Tacoma Rail in late 2014, and were later sold to Arkansas & Missouri Railroad in late 2023.
On January 1, 2015, the United States Environmental Protection Agency's Tier 4 locomotive emission regulations went into effect. EMD could not successfully modify the SD70ACe's 2-stroke 710 series prime mover to be Tier 4-compliant; thus, the Tier 3 SD70ACe was succeeded by the SD70ACe-T4 in late 2015. However, US production of the Tier 3-compliant SD70ACe continues with Tier 4 'credit units'. Union Pacific and Norfolk Southern are currently the only US roads to own Tier 4 credit unit SD70ACe's. Additionally, EMD has continued building Tier 3 SD70ACe's for Ferromex, Ferrosur, and Kansas City Southern de Mexico at Bombardier Ciudad Sahagun. These locomotives are restricted to Mexico-only operation and cannot cross the US border.
In March 2016, EMD replaced the standard cast HTCR-4 trucks on NS SD70ACe 1000 with the new fabricated HTCR-6 trucks for testing. UP and BNSF plan to test the new HTCR-6 trucks on some of their SD70ACe units also.
Union Pacific received 281 additional SD70ACe units, numbered 8824 - 9104, in 2014, 2016 and 2018. These are referred to as SD70AH , H for "heavy", because they are ballasted to rather than.

2TE3250 (2021)

In mid-2021, the Yakutian Railway received two SD70ACes, designated 2TE3250 by Yakutian Railway itself. These units, numbered 0001 and 0002, are currently in use in Yakutia, and are operated as a two-section locomotive.
In November 2021, Yakutian Railway announced a tender for six more, single-section locomotives. However, as of 4 February 2022, it has been unable to make an order for them.

SD70M-2 (2004–2011)

The SD70M-2 is a DC traction version of the SD70ACe. The "-2" in the model name indicates that the units are EPA Tier II compliant and that the locomotive has upgraded electronics, which was true for older models. SD70M-2 models are equipped with the 16-710G3C-T2 or 16-710G3C prime mover which is rated at.
In total, 331 SD70M-2s were built, with Canadian National owning 190 units. Eight units owned by Electro-Motive Diesel and four units owned by CIT Financial were leased by Florida East Coast Railway until early 2015. Canadian National 8964 was the last SD70M-2, built in February 2011. Vermont Railway owns 2 units numbered 431 and 432. Norfolk Southern ordered 130 SD70M-2s, of which 46 remained in service as of July 2023 with 2 units rebuilt with AC traction.
Currently, NBM Railways owns 13 SD70M-2, former NS units, numbered 6401–6413 with plans for six more rounding it out to 6419. All are marked for the various NBM companies, New Brunswick Southern Railway, Eastern Maine Railway, and Maine Northern Railway.