EMD SD90MAC

SD9043MAC locomotive No. 8027 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 engine resulted in the first locomotives being shipped with 16-cylinder 710G engines, making them similar to the SD70MACs. These locomotives were informally designated SD9043MAC by railroads that purchased them with the option to re-engine them with 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 710 engine were built. In 1996, Electro-Motive Diesel entered full production on their , 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 Electro-Motive Diesel 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 and Canadian Pacific. The Canadian Pacific locomotives were part of an earlier order for 710-engine equipped SD90MAC locomotives that was still in production when Electro-Motive Diesel switched over to the H-engine. Electro-Motive Diesel 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==

7332 in Ohio Prime mover (EMD 710): • EMD V16 710G3C-T1 • Power Output - at 900 rpm • Idle - 200 rpm • Full Speed - 950 rpm Prime mover (EMD 265): • EMD V16 EMD GM16V265 • Power Output - at 1,000 rpm • Idle - 200 rpm • Full speed - 1,000 rpm Traction motors: • 6 Siemens 1TB2830 AC motors mounted 3 each on 2 HTCR-2 radial self-steering trucks. • Rated output - • Gearing - 83:16 • Wheel size - • Max revolutions - 3,435 rpm • Starting torque - • Continuous torque - • Maximum voltage - 2,183 V Performance (parenthesis indicate H-Engine equipped specifications): • Maximum speed - • Starting tractive effort - and ) • Continuous tractive effort - and ) • Braking effort - • Weight - / ==Fleet rosters==

SD70ACU No. 7305. The SD70ACU was part of Norfolk Southern's SD90MAC rebuild program. 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 had planned to be able to get the H-engine approved at some later date. However, 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, Fortescue units 910 to 917 were stored. They were purchased to be used as slave units, and were more offline than they were in use. All were scrapped in 2022. On 1 August 2008, Union Pacific announced that it would be retiring 21 of the SD90MAC locomotives. 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 not reusable is the frame. These units, in the 8900 series will be removed from storage in Denver, and will be sent to East St. Louis, in small batches to be dismantled. As of 2019, Union Pacific still operates some of the remaining SD9043MACs, which sport new numbers and UP wings on the cab. These units take the original road numbers of the Union Pacific's original SD40-2 fleet. Canadian Pacific's SD90MAC-H locomotives 9300-9303 (listed as SD90MAC6000s) were up for tendered sale in 2009. The bidding ended 31 March 2010. While they were originally thought to be shipped overseas, they were eventually moved to Quebec for scrapping. Canadian Pacific's SD90MAC locomotives, numbered in the 9100–9160 series had been in long-term storage in Winnipeg, Manitoba, for much of the 2010 decade. Three units, the 9129, 9133 and 9138, were scrapped in November 2012 due to errors in preparing them for long-term storage. The entire fleet had been put up for sale in November 2012 and again in January 2013 with no offers being received. These units remained stored until the winter of 2018 when at first 30, then all 58 remaining units entered a rebuild program to be converted into SD70ACUs. In 2021, Canadian Pacific purchased 40 more SD90MACs from the Union Pacific for further rebuilding into SD70ACU engines. In September 2014, Norfolk Southern purchased 100 4300 hp SD9043MACs from Union Pacific with the intent to rebuild them into SD70ACUs at the Juniata Shops. The last four SD90MACs were delivered to Norfolk Southern on October 3, 2015, running parallel to Western Avenue in Chicago. In 2015, Cummins rebuilt a single SD90MAC 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 1919, had been Union Pacific 8559. ==See also==