Power type Diesel-electric Wheel diameter 42 in (1,067 mm) | AAR wheel arr. C-C Length 80 ft 2 in (24.43 m) | |
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Builder Electro-Motive Diesels (EMD) Gauge 4 ft 8 ⁄2 in (1,435 mm) | ||
The EMD SD90MAC is a 6,000 hp (4,470 kW) C-C diesel-electric hood unit locomotive produced by General Motors Electro-Motive Division. It is, with the SD80MAC, one of the largest single-engined locomotives produced by that company, surpassed only by the dual-engined DDA40X.
Contents
The SD90MACs feature radial steering trucks with AC traction motors and an isolated safety cab which is mounted on shock absorbers to lessen vibrations in the cab. The SD90MAC, like the SD80MAC, SD70ACe, and SD70M-2, has a wide radiator section, nearly the entire width of the locomotive, which along with their size makes them easy to spot.
History
The SD90MAC was introduced in 1995, along with the SD80MAC locomotives. The SD90MAC was designed to utilize the new 16-cylinder H-engine, while the SD80MAC was designed to use the 20-cylinder version of the existing 710G engine. However, technical problems with the 6,000 horsepower (4,500 kW) engine resulted in the first locomotives being shipped with 4,300 hp (3,210 kW) 16-cylinder 710G engines, making them similar to the SD70MACs. These locomotives were given the informal model designation SD9043MAC by railroads that purchased them with the option to re-engine them with 6,000 hp (4,470 kW) engines when they became available. This upgrade program, however, was never taken advantage of by SD90MAC buyers due to reliability issues with the newer engine. Over 400 SD90MAC locomotives fitted with the 4,300 hp (3,210 kW) 710 engine were built.
In 1996, EMD entered full production on their 6,000 hp (4,470 kW), 16-cylinder H-engine, and all SD90MACs made from then on used that for its prime mover. Locomotives fitted with this engine are sometimes referred to as SD90MAC-H locomotives. Later versions of the SD90MAC-H feature a Phase II cab, with a new nose which offers higher visibility from the cab than the old nose. The SD90MAC-H did not prove popular with railroads and less than 70 were built, including EMD demonstrator units. Since the SD90MAC-H had such a large prime mover, it didn't offer the same operational flexibility as smaller units, limiting its possible customer base to only the largest railroads. Also, since the H-engine was a new design it hadn't reached the same level of reliability as EMD's previous engine. The low reliability on such a large engine was an especially bad combination since the loss of one engine in a train meant the loss of a larger percentage of pulling power than had a smaller engine failed. In the end the SD90MAC-H was only delivered to two railroads, the Union Pacific Railroad and the Canadian Pacific Railway. The Canadian Pacific locomotives were part of an earlier order for 710-engine equipped SD90MAC locomotives that was still in production when EMD switched over to the H-engine.
EMD also tried offering a lower-power version of the SD90MAC with a 12-cylinder engine called the SD89MAC, but none were produced other than the prototype.
Specifications
Prime mover (EMD 710):
Prime mover (EMD 265):
Performance (parenthesis indicate H-Engine equipped specifications):
Fleet rosters
Canadian Pacific
CEFX
EMLX
Indiana Rail Road
Norfolk Southern
Union Pacific:
Fortescue Metals Group
Current status
As of January 2005, the SD90MAC is no longer in production due to the Environmental Protection Agency's Tier 2 locomotive emission regulations, although EMD may be able to get the H-engine approved at some later date. However, the People's Republic of China recently announced an order for 300 JT56ACe locomotives, which also use the H-Engine as its prime mover. A portion of the locomotives will be assembled in kit form by China's own Dalian Locomotive Works. These units were reportedly capable of meeting the EPA's strict regulations and began delivery in the latter half of 2007.
Due to reliability issues FMG units 910 to 917 are stored and deemed not be used. Purchased to be used as "slave" units they were more offline than they were in use
Update
On August 1, 2008 Union Pacific Railroad announced that it would be retiring 21 of the SD90MAC locomotives. According to sources [3] common parts will be used to maintain the railroad's 710-engined SD90MAC fleet. The 265H prime mover will be cut up or exported. The only part that is non-reusable will be the frame. These units, in the 8900 series will be removed from storage in Denver, and be sent to East St. Louis, Ill., in small batches to be dismantled.
CPR SD90MAC-H locomotives 9300-9303 (listed as SD90MAC6000s) were up for tendered sale in 2009. The bidding ended March 31, 2010. While they were originally thought to be shipped overseas, they were eventually moved to Quebec for scrapping.
CPR SD90MAC 58 locomotives remaining in the 9100-9160 series (9129, 9133 & 9138 scrapped Nov. 2012) had been put up for sale as of November 2012 and again in Jan. 2013 with no offers being made.
In September 2014, Norfolk Southern purchased 100 4300hp SD9043MACs from Union Pacific with the intent to rebuilt them into SD70ACu's at the Juniata Shops. The last 4 SD90-MACS were taken delivery to Norfolk Southern on October 3, 2015.
Rebuilds
In 2015 Cummins rebuilt a single SD90AC with its QSK95 engine, designed to meet Tier 4 emissions standards. Sygnet Rail Technologies and Brookville Equipment Corporation performed the conversion. The rebuild was designated HTL4200AC. The locomotive, numbered CECX No. 1919, had been Union Pacific No. 8559.