An SDP40 is a 6-axle passenger diesel-electric locomotive built by

General Motors Electro-Motive Division Progress Rail Locomotives, doing business as Electro-Motive Diesel (EMD), is an American manufacturer of diesel-electric locomotives, locomotive products and diesel engines for the rail industry. The company is owned by Caterpillar through its su ...

(EMD) between June 1966 and May 1970.

Design

Like its predecessor in EMD's catalog, the SDP35, the SDP40 is a high-horsepower freight locomotive with equipment for

passenger train A passenger train is a train used to transport people along a railroad line. These trains may consist of unpowered passenger railroad cars (also known as coaches or carriages) hauled by one or more locomotives, or may be self-propelled; self p ...

service. In 1966, EMD replaced all their production units with those powered by the new

645 __NOTOC__ Year 645 ( DCXLV) was a common year starting on Saturday (link will display the full calendar) of the Julian calendar. The denomination 645 for this year has been used since the early medieval period, when the Anno Domini calendar era ...

diesel. They included six-axle models SD38, SD40 and

SD45 The SD45 is a six-axle diesel-electric locomotive built by General Motors Electro-Motive Division between 1965 and 1971. It has an EMD 645E3 twenty- cylinder engine generating on the same frame as the SD38, SD39, SD40, and SDP40. As of 2022, ...

, in addition to SDP40. All had standard components including the frame, cab, generator, trucks, traction motors, and air brakes. The main difference was the power: the SD38 produced from a non-turbocharged V16, the SD40 produced from a turbocharged V16, and the SD45 produced from a turbocharged V20. The SD40 and SDP40 were so similar that EMD published common operator's and service manuals to cover both. At the time most passenger locomotives needed to provide

steam Steam is a substance containing water in the gas phase, and sometimes also an aerosol of liquid water droplets, or air. This may occur due to evaporation or due to boiling, where heat is applied until water reaches the enthalpy of vaporizatio ...

to the

passenger cars A car or automobile is a motor vehicle with wheels. Most definitions of ''cars'' say that they run primarily on roads, seat one to eight people, have four wheels, and mainly transport people instead of goods. The year 1886 is regarded as t ...

for heating, cooking, and sometimes cooling. They needed a higher gear ratio for faster running, the graduated-release feature on the air brakes, and type F tightlock

couplers Coupler may refer to: Engineering Mechanical * Railway coupler, a mechanism for connecting rolling stock in a train device ** Janney coupler ** SA3 coupler ** Scharfenberg coupler for multiple unit passenger cars * Quick coupler, used in construc ...

to keep equipment together in the event of a derailment. To fit a steam generator to the freight-only SD40, the designers had to move the machinery forward about on the frame, add a compartment behind the radiators for the boiler, and divide the fuel tank into fuel and water sections.

Appearance

Earlier passenger diesels, like EMD E8, ALCO PA, FM Erie-built and Baldwin Sharknose locomotives, were streamlined

cab unit In North American railroad terminology, a cab unit is a railroad " locomotive" with its own cab and controls. "Carbody unit" is a related term, which may be either a cabless booster unit controlled from a linked cab unit, or a cab unit that con ...

s designed for visual appeal and the appearance of speed. The SDP40 and the SDP35 & SDP45 instead have the same appearance as their freight counterparts. This look was contemporary to, and eventually overtaken by

cowl unit A cowl unit is a body style of diesel locomotive. The terminology is a North American one, though similar locomotives exist elsewhere. A cowl unit is one with full-width enclosing bodywork, similar to the cab unit style of earlier locomotives, b ...

s like the GE U30CG and

EMD FP45 The EMD FP45 is a cowl unit type of C-C diesel locomotive produced in the United States by General Motors Electro-Motive Division (EMD). It was produced beginning in 1967 at the request of the Atchison, Topeka and Santa Fe Railway, which did not ...

, SDP40F and F40PH. Visually, the locomotive is a

hood unit A hood unit, in North American railroad terminology, is a body style for diesel and electric locomotives where the body is less than full-width for most of its length and walkways are on the outside. In contrast, a cab unit has a full-width ...

distinguished only by the shape of its rear end behind the radiators, with its flat end having no number boards, shuttered boiler air intake on each side, extra exhaust stacks over the boiler, cantilevered walkway around the flat end, and very steep rear steps. EMD applied this same end to the passenger SDP35, SDP45, and

GP40P The passenger locomotives derivatives of the General Motors EMD GP40 diesel-electric locomotive have been, and continue to be, used by multiple passenger railroads in North America. For passenger service, the locomotives required extra componen ...

locomotives, as well as the freight DD35, DDA40X and SD40T-2.

Amtrak The National Railroad Passenger Corporation, doing business as Amtrak () , is the national passenger railroad company of the United States. It operates inter-city rail service in 46 of the 48 contiguous U.S. States and nine cities in Canada. ...

's SDP40F locomotive, although sharing several mechanical specifications, is visually a much different locomotive. Seven years separate their introductions, and the SDP40F was actually based on the SD40-2. It had a full-width carbody, similar to the FP45. It was also longer than the SDP40.

Original Owners

Great Northern Railway (GN) purchased the first six SDP40s in 1966, to replace older E-units on their '' Western Star'' and smaller regional trains. Options included Vapor OK-4740 steam generators, water-transfer capability between units, 59:18 gearing for a top speed of , and Type-F couplers. These were followed in 1967 by eight more powerful SDP45 locomotives ordered for the '' Empire Builder''. After the startup of

in 1971, Great Northern's successor

Burlington Northern Railroad The Burlington Northern Railroad was a United States-based railroad company formed from a merger of four major U.S. railroads. Burlington Northern operated between 1970 and 1996. Its historical lineage begins in the earliest days of railroadi ...

(BN) converted the locomotives to freight service. One SDP40, former GN 323, was temporarily renumbered BN 1976 and painted in red, white and blue for the

United States Bicentennial The United States Bicentennial was a series of celebrations and observances during the mid-1970s that paid tribute to historical events leading up to the creation of the United States of America as an independent republic. It was a central event ...

in 1976. NdeM had ten units delivered in 1968 and another four in 1970. In 1998, the government of

Mexico Mexico (Spanish language, Spanish: México), officially the United Mexican States, is a List of sovereign states, country in the southern portion of North America. It is borders of Mexico, bordered to the north by the United States; to the so ...

privatized the NdeM the locomotives were split between two successor companies. Eight went to TFM, which was later purchased by Kansas City Southern Railway and became KCSM. Of those eight, two were rebuilt to SD22ECOs, and the other six were scrapped. The remaining six went to

Ferromex Ferromex (syllabic abbreviation of Ferrocarril Mexicano or "Mexican Railway") is a private rail consortium that operates the largest (by mileage) railway in Mexico with combined mileage (Ferromex + Ferrosur) of and is part of the North American ...

. Of those six, four were rebuilt to SDP40-2s and remain in service, the other two were scrapped.

Roster

Wrecks

On August 23, 1979, BN 6399 was the lead unit of train 23 when it ran head-on into train 182 at Maiden Rock, WI. 6399 was repaired and returned to service, where it remained until its retirement, and it was eventually donated to the Minnesota Transportation Museum, where it still operates today. The four units of the other train were also repaired. The three trailing GP40 units were destroyed.

Rebuilds

*
FNM 13099
' was rebuilt by the San Luis Potosi shops, but the original locomotive number is unknown. The steam generator air intake was plated over during the rebuild. *
FXE 3227
' appears to have been rebuilt from an SDP40, but the original locomotive number is unknown. The steam generator air intake was plated over during the rebuild, but it retained the full compartment and vertical rear steps. *
MRL 290
' was wrecked in 1988, and subsequently sold to MRL. It is listed in rosters and lettered as an SDP40-2XR. Its steam generator air intake was plated over during the rebuild, but it retained the full compartment and vertical rear steps. *
GCFX 3093
' sources suggest was remanufactured by Alstom to SD40-2 specifications. Much of the steam generator compartment was removed to permit installation of compliant rear switching steps. *
KCS 1319
' was rebuilt by EMD in London, ON during August 2009 into an SD22ECO, keeping its external appearance. *
KCS 1320
' was rebuilt by EMD in London, Ontario during August 2009 into an SD22ECO, keeping its external appearance.

Preservation

BNSF Railway BNSF Railway is one of the largest freight railroads in North America. One of seven North American Class I railroads, BNSF has 35,000 employees, of track in 28 states, and nearly 8,000 locomotives. It has three transcontinental routes that ...

donated #6327 - former

Great Northern Great Northern may refer to: Transport * One of a number of railways; see Great Northern Railway (disambiguation). * Great Northern Railway (U.S.), a defunct American transcontinental railroad and major predecessor of the BNSF Railway. * Great ...

#325 and their last SDP40 in service - to the

Minnesota Transportation Museum The Minnesota Transportation Museum (MTM, reporting mark MNTX) is a transportation museum in Saint Paul, Minnesota, United States. MTM operates several heritage transportation sites in Minnesota and one in Wisconsin. The museum is actively involv ...

in May 2009. Since then, it has been in service on the

Osceola and St. Croix Valley Railway The Osceola and St. Croix Valley Railway is a heritage railroad in Osceola, Wisconsin owned and operated by the Minnesota Transportation Museum. It operates on former Minneapolis, St. Paul and Sault Ste. Marie Railroad ("Soo Line") trackage no ...

References

* * * Shine, Joseph W. (1992). Great Northern Color Pictorial - Volume 2: Division Assignment, Second Generation Diesels, The Big Sky Blue Era. La Mirada, CA: Four Ways West Publications. * Strauss, John F. Jr. (1998). Great Northern Color Pictorial - Volume 5: Rocky's Robe of Many Colors. La Mirada, CA: Four Ways West Publications. *
The UNofficial EMD Homepage
'. Retrieved on May 1, 2009 * Sarberenyi, Robert.

'. Retrieved on May 5, 2009 *

'. Retrieved on May 5, 2009 *
KCS NAFTA Rosters
'. Retrieved on May 5, 2009 * Service Department (1966). SD40 - SDP40 Operator's Manual. La Grange, IL: Electro-Motive Division of General Motors Corporation * * *

'. Retrieved on July 25, 2010 {{DEFAULTSORT:Emd Sdp40 SD40P C-C locomotives Passenger locomotives Diesel-electric locomotives of the United States Railway locomotives introduced in 1966 Standard gauge locomotives of the United States Standard gauge locomotives of Mexico Diesel-electric locomotives of Mexico