SD70/70M/70I/70MAC
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SD70M
The Electromotive Division SD70M is a 6 axle, 4,000 HP diesel-electric locomotive built by EMD (by this time EMD was now manufacturing 100% of it's locomotives at the London, ON plant) from 1992 to 2004. It uses a 16 cylinder 710 prime mover to generate 4,000 HP, and rides on the EMD HTCR radial self-steering truck, which replaced the older HTC truck that had been used since the introduction of the SD40-2.
Seeking to counter GE's new C44-9W locomotive, EMD improved upon the SD60M design and came up with the SD70M. The SD70M was EMD's most powerful 16 cylinder locomotive to date, and while it didn't sell as many units as the C44-9W, it is generally considered a sucessful and fairly reliable locomotive. The original railroads that ordered SD70M's were EMD, New York, Susquehanna & Western, Norfolk Southern, Southern Pacific and Union Pacific. Union Pacific made the largest single locomotive order in history when they bought over 1,000 SD70M's in late 1999.
The SD70M used the 2-window North American safety cab introduced on the SD60M, known as the "Phase 1" cab. On later SD70M orders, EMD began building the units with what is known as the "Phase 2" cab, featuring a more squared off nose similar to the cab later used on the SD70M-2 and SD70ACe. Also in mid 2000, EMD began building SD70M's (along with SD70MAC's) with flared radiators similar to those once used on the SD45. The flared radiators did a better job of cooling off the engine than the older style flush version.
The SD70M is still a widely used locomotive today. Union Pacific's massive fleet (including the former SP SD70M's) can be seen all over North America in run through and pool service, while CSX's ex EMD units are largely kept in rock train service in Florida. NS uses their SD70M's, along with the SD70's, all across the system.
Roster of SD70M's
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SD70
The Electromotive Division SD70 is identical to the SD70M, but uses the older style "Spartan" cab instead of the North American "Safety" or "Wide" cab used on the SD70M and the previous SD60M. Conrail, Norfolk Southern, Illinois Central, and Southern Peru Copper were the only railroads to order the SD70. The SD70 was offered for railroads who felt the Safety cab wasn't necessary. Conrail's 24 SD70's were originally going to be built as SD80MAC's, but with the pending split of Conrail between CSX and Norfolk Southern, the order was split into 24 SD70's for NS and 15 SD70MAC's for CSX, making Conrail unique at the time among railroads because it ordered AC and DC locomotives simultaniously.
A total of 120 SD70's were built, and aside from a few wrecked units, all remain in service today. Conrail's SD70's joined NS's fleet, and IC's became property of Canadian National after the two railroads merged in 1999.
Roster of SD70's
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SD70I
The Electromotive Division SD70I is a varient of the SD70M built by EMD in 1995. Canadian National was the sole purchaser, ordering 26 units. The SD70I is identical to the SD70M, except it uses the isolated or "Whisper" cab used on the SD60I, SD80MAC, SD90MAC, and later SD70MAC's. It was the last EMD locomotive to use the "I" designation. All 26 remain in service on CN, numbered CN 5600-5625.
SD70MAC
The Electromotive Division SD70MAC is the AC traction version of the SD70M, built from 1994 to 2004. Like the SD70M, it uses a 16 cylinder 710 engine to produce 4,000 HP. Based on the pioneering AC technology first used in the SD60MAC, the SD70MAC improved upon and perfected the art of AC traction. Normal DC locomotives, like the SD70M, have alternators that turn the AC current generated by the prime mover into DC current before it gets to the traction motors. Under heavy loads at low speeds, DC traction motors can overheat because of the alternator. But in AC traction locomotives like the SD70MAC, there is no alternator, and straight AC current goes right to the traction motors. This results in no danger of "overloading", so an SD70MAC can get right down on it's knees and pull at full power going 1 mph if need be, a scenario that would fry the traction motors of conventional DC locomotives. This attribute made AC locomotives well suited for high tractive effort, low speed service like pulling long, heavy coal or merchandise trains over steep grades.
Burlington Northern was the first railroad to order the SD70MAC, ordering 315 units to put to work hauling coal in the Powder River Basin. The BN SD70MAC's were delivered in the then new BN "Executive" cream and green paint scheme. BN sucessor BNSF eventually ordered more SD70MAC's as well. Other railroads who ordered SD70MAC's include Alaska Railroad, Conrail, CSX and Kansas City Southern's Mexican subsidiary Grupo Transportacion Ferroviaria Mexicana, or TFM.
SD70MAC's are still the back bone of BNSF's Powder River Basin fleet today. CSX also employs their SD70MAC's (along with the 15 inherited from Conrail) in coal service, while Alaska RR uses their units on everything from locals to passenger trains.
Roster of SD70MAC's
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SD70ACe
The Electromotive Diesel (GM sold it's Electromotive Division in 2005) SD70ACe is a 6 axle, 4,300 HP diesel-electric locomotive built by EMD from 2004-present. The SD70ACe was developed from the SD70MAC in order to meet the tough new Tier II emmissions standards set by the EPA. The SD70ACe uses the same basic AC technology as the SD70MAC, but is a radical departure in styling from the old locomotive. The SD70ACe sports what is now know as the "Phase 3" cab, featuring a very square nose with a square door and rectangular windshield windows instead of the older tear drop style. The SD70ACe also has large radiator wings as wide as the locomotive's cab, similar to the ones used on the SD80MAC and SD90MAC. The SD70ACe's ride on EMD's new bolsterless HTCS truck, but radial trucks (now dubbed HTCR-4) are still optional.
Several North American railroads have ordered the SD70ACe. Union Pacific has been one of the types biggest customers, even painting some of it's SD70ACe's in Heritage paint schemes for railroads UP has merged with. They include numbers 1982 (Western Pacific), 1983 (Missouri Pacific), 1988 (Missouri-Kansas-Texas), 1989 (Rio Grande), 1995 (Chicago & Northwestern) and 1996 (Southern Pacific). UP also painted and renumbered an SD70ACe to 4141, honoring the 41st President of the united States, George H.W. Bush and the opening of his presidential library. Wearing a paint scheme similar to that of Air Force One, the 4141 has been dubbed "Railroad One".
EMD also builds an export version of the SD70ACe, called the SD70ACe/lc, the "lc" standing for "low clearence".
In recent times, EMD has begun building SD70ACe's compliant with EPA Tier III, and now Tier IV, emmissions standards. Externally these units look like past units with a few minor variations (mostly on the longhood).
Roster of SD70ACe's
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SD70M-2
The Electromotive Diesel SD70M-2 is the DC traction version of the SD70ACe. In a nutshell, the SD70M-2 is a slightly more powerful, updated and more eco-friendly SD70M. Externally it is virtually identical to the SD70ACe, sharing the same body components and riding on the same trucks. The SD70M-2 hasn't yet proven to be as popular as the SD70ACe, with only a few being built for 4 different railroads, the most noteable of which are the 8 units ordered by regional Florida East Coast, who uses them primarily on their fast intermodal trains. Canadian National also ordered SD70M-2's, the first of which coming as-is from EMD with the standard cab headlight and numbered in the 8000 series. The next orders started at 8800 and featured nose headlights and cab mounted marker lights for DPU service. Canadian National currently rosters the most SD70M-2's with 140 units delivered with more on order. EMD also built 3 SD70M-2 demonstrators which were later bought by CIT Financial.
In recent times, EMD has begun building SD70M-2's compliant with EPA Tier III, and now Tier IV, emmissions standards. Externally these units look like past units with a few minor variations (mostly on the longhood).
Roster of SD70M-2's
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