# EMD MP15DC

The EMD MP15, sometimes referenced as MP15DC, is a 1,500 hp (1,119 kW) diesel–electric road switcher locomotive model produced by General Motors' Electro-Motive Division between 1974 and 1980. It was equipped with a V12 12-645E engine sporting a Roots blower. The length was either 47 ft 8 in (14.53 m) or 48 ft 8 in (14.83 m) depending on the build date.
The early MP15 and the SW1500 were similar in appearance and applications. They were fitted with the same engine in a similar appearance. The primary difference is the MP15's standard Blomberg B trucks.

## Development

Switchers up to the SW1500 had been restricted to AAR type A switcher or Flexicoil lightweight trucks, both with a 96 in (2,438 mm) wheelbase. In 1973 60 special order Mexico-only SW1504s were built on a slightly longer frame, allowing EMD's standard Blomberg B trucks, with a 108 in (2,743 mm) wheelbase, to be used. In EMD's eyes (among others) this made the new locomotive a road switcher rather than a pure switcher, since it was capable of road speeds up to 60 mph (97 km/h) or so. The new model MP15DC designation thus meant Multi-Purpose locomotive, 1500 hp, DC generator. Originally the locomotive was simply designated the MP15; the arrival of the alternator/rectifier MP15AC in 1975 changed the name.
With the success of the MP15, there was a demand for a model with an advanced AC drive system. The MP15AC replaced the MP15DC's DC generator with an alternator producing AC power which is converted to DC for the traction motors with a silicon rectifier. The MP15AC is 1.5 ft (457 mm) longer than an MP15DC, the extra space being needed for the rectifier equipment. The alternator-rectifier combination is more reliable than a generator, and this equipment became the standard for new diesel-electric locomotive designs.
The MP15AC is easily distinguished from the DC models. Instead of the front-mounted radiator intake and belt-driven fan used on all previous EMD switchers, these have intakes on the lower forward nose sides and electric fans. Side intakes allowed the unit to take in cooler air, and the electric fans improved a serious reliability issue found in its earlier DC sisters.

## Engine

The MP15 used a 12-cylinder version of the 645E series engine developing 1,500 hp at 904±4 rpm. Introduced in the SW1500, this was a 2-stroke, 45-degree V type, with a 9 1⁄16-inch bore by 10-inch stroke, giving 645 cubic inches displacement per cylinder.$^{:0–1,7B-SSS-1}$ The 645 series, introduced in 1966, was EMD's standard engine through the 1980s.$^{:26}$

## Original buyers

| Railroad | Quantity | Road numbers | Notes |
| Alcoa | 1 | 7 | |
| Alton and Southern Railway | 1 | 1522 | |
| Altos Hornos de México | 5 | 146–148, 159, 166 | |
| American Cyanamid | 2 | 18, 19 | |
| Arizona Public Service | 1 | 2 | |
| Bauxite and Northern Railway | 2 | 15, 16 | |
| BC Hydro | 3 | 151–153 | |
| Belt Railway of Chicago | 4 | 533–536 | |
| Birmingham Southern Railroad | 2 | 260, 261 | |
| Cambria and Indiana Railroad | 2 | 19, 20 | |
| Chicago and Northwestern | 15 | 1302–1316 | C&NW 1313 retired prior to UP merger. Remaining 14 units renumbered to UP 1315–1328 in 2000–2001. |
| Cities Service | 1 | 109 | |
| Conn. Davison Chemical Division | 4 | 121, 122, 131, 132 | |
| Genesee and Wyoming Railroad | 2 | 45, 46 | |
| Georgetown Railroad | 2 | 1011, 1012 | |
| Graysonia, Nashville & Ashdown Railroad | 1 | 80 | |
| Gulf Oil | 1 | 101 | |
| Houston Belt & Terminal Railroad | 5 | 60–64 | |
| Industrial Minera México | 2 | 383, ? | |
| Kansas City Southern Railway | 4 | 4363–4366 | |
| Kelly's Creek and Northwestern Railroad | 2 | 1, 2 | |
| Lake Erie, Franklin and Clarion Railroad | 4 | 25–28 | |
| Louisville and Nashville Railroad | 10 | 5030–5039 | |
| Manufacturers Railway | 3 | 251, 252, 254 | |
| Metropolitan Sanitary District of Greater Chicago | 1 | 4 | |
| Missouri Pacific Railroad | 62 | 1530–1554, 1356–1392 | #1530 was the first MP15 built; renumbered by UP as 1330–1392 between 1986 and 1993. |
| North Louisiana and Gulf Railroad | 4 | 42–45 | |
| Pittsburgh and Lake Erie Railroad | 25 | 1574–1598 | 15 units sold to Union Pacific in 1985 (1574-1583 and 1584, 1587, 1588, 1596 and 1598). Repainted and numbered 1300-1314 by UP in 1987. |
| Point Comfort and Northern Railway | 5 | 11–15 | |
| Quebec Iron and Titanium | 2 | 9, 10 | |
| Reading Company | 10 | 2771–2780 | Equipped with remanufactured and renewed ALCO RS-3 truck assemblies, including the General Electric 752 traction motors. To Conrail as #9621–9630 |
| Rockdale, Sandow and Southern Railroad | 3 | 13–15 | |
| Southern Pacific Railroad | 12 | 2690–2701 | 2691 and 2692 retired in 1994 and sold to Progress Rail, then OmniTRAX, and then Helm Financial, which leased them to Union Pacific as 1289 and 1290; these retired from UP in 2002 and sold to Caltrain in 2003 as 503 and 504. 2690 rebuilt by Union Pacific in 2005 and renumbered to 2005 as a GS14B Truck Engine Switcher, which was the first Genset locomotive. 2697 retired prior to merger with UP; remaining eight (2693-2696;2698-2701) renumbered consecutively as UP 1292-1299 after merger. |
| Southern Railway | 88 | 2348–2435 | |
| St. Louis–San Francisco Railway | 5 | 361–365 | To Burlington Northern Railroad as #4000–4004, later renumbered to #1000–1004 |
| St. Mary's Railroad | 2 | 504, 505 | |
| Swift Chemical Company | 1 | 1976 | |
| Tennessee Eastman | 1 | 2 | |
| Terminal Railway Alabama State Docks | 7 | 761, 771, 772, 801, 802, 821, 822 | |
| Texas and Northern Railway | 2 | 998, 999 | |
| Texas City Terminal Railway | 3 | 35–37 | Split from the last Missouri Pacific order of MP15DCs. Painted and lettered for Missouri Pacific |
| Union Railroad | 24 | 10–33 | |
| U.S. Steel | 15 | 170, 955–968 | |
| Total | 351 | | |