These locomotives were built as a response to General Electric's Dash 9-44CW, where as their cousins, the SD70MAC, were built in response to General Electric's AC4400CW. By increasing the output of the 16-710-G3 engine from 4,000 to 4,300 horsepower (3,000 to 3,200kW), the SD75 was a reality. The "M" in the model designation is the style of the cab, in this case the North American style cab.
SD75M
The SD75M is a diesel-electric locomotive built by GM-EMD. It is a further extension to the 70's series, but can be distinguishable from the SD70M by the bulge below the inertial air-intake on the right side of the unit. But, however, it was not successful, as it sold only 76 units. Buyers were Santa Fe Railway and BNSF Railway. Soon, Progress Rail (PRLX) acquired three Santa Fe SD75M locomotives. [2] PRLX locomotives are distinguishable by the original railroad's name being hidden by black patches, on both sides and the nose. PRLX was written on both the sides on the patches.
The SD75I has an isolated cab in EMD's range. This is indicated by the "I" designation, which means that it has an "Isolated Cab", or a "WhisperCab" in EMD speak, which reduces noise and vibration in the cab. This type of cab is recognized by a seam separating the nose and cab components, similar to the SD70I and SD60I. This seam is the rubber that damps vibration and cuts down on noise, because the cab is not attached directly to the frame on the unit. Models like the SD60I, SD70I, etc. used the "I" designation. This was the last model that used the "I" designation in the model name; all further units had the isolated cab, but the model designation continued to use the "M". Buyers included Canadian National, the largest buyer with 175 units (now 173), Burlington Northern Santa Fe with 26 (now 24), and Ontario Northland Railway with 6 (now 5).
Other
Both models use the HTCR radial truck and are mounted on the 72-foot-4-inch (22.05m) frame. The M model sold only 76 units and was not as popular as the SD70M. The biggest buyer of this model was the Atchison, Topeka and Santa Fe Railway, now Burlington Northern Santa Fe, with 51 units; an additional 25 were delivered in early 1996, during the merger process. The Santa Fe's SD75Ms were the railroad's last new locomotives, with the last new unit, number 250, built in August 1995. PRLX then acquired 3 consecutive Santa Fe SD75M's, numbered 231, 232, and 249. [3]
Mainly built for a special request from Santa Fe/BNSF, the SD75Ms are slightly more powerful than SD70Ms, having horsepower ratings between 4,300hp (3,200kW) & 4,500hp.
The SD75IACC is a rebuild of Canadian National's SD75I's by Progress Rail, and entered service in July 2024. These replace the DC traction system with an AC traction system. The program started in 2023.[5]
SD75M operators
Railroad
Quantity
Road Numbers
Notes
Atchison, Topeka and Santa Fe Railway
51
200–250
To BNSF 8200–8250, then back to 200–250. Units 202, 209, 218, 222, 225, 229, and 230 to Norfolk Southern 2800–2806. Rest sold to PRLX.
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