EMD SD50 - AbsoluteAstronomy.com

The EMD SD50 was a 3500 hp diesel-electric locomotive built by General Motors Electro-Motive Division. It was introduced in May 1981 as part of EMD's "50 Series", but prototype SD50S locomotives were built from 1980; production ceased in January 1986. The SD50 was in many respects a transitional model between EMD's Dash 2

EMD Dash 2

On January 1, 1972, General Motors' Electro-Motive Division introduced its new Dash 2 line of diesel-electric locomotives. All designations of these new models were those of the former models with "-2" added...

series which was produced throughout the 1970s and the microprocessor-equipped SD60

EMD SD60

The EMD SD60 is a 3,800 horsepower 6-axle diesel-electric locomotive built by General Motors Electro-Motive Division. Intended for heavy-duty drag freight or medium-speed freight service, it was introduced in 1984, and production of SD60 variants ran until 1995.- History and development...

and SD70 locomotives.

History

The SD50 was produced in response to increasingly tough competition from GE Transportation Systems

GE Transportation Systems

GE Transportation, formerly known as GE Rail, is a division of General Electric. The organization manufactures equipment for the railroad, marine, mining, drilling and energy generation industries. It is based in Erie, Pennsylvania. Locomotives are assembled at the Erie plant, while engine...

, whose Dash 7 line was proving quite successful with railroads. While EMD's SD40-2 was a reliable and trusted product, GE's line included locomotives up to 3600 hp with more modern technology, as well as very competitive finance and maintenance deals. EMD responded throughout the SD50 program by offering discounts on large orders, this was also a response to the slow U.S. economy in the 1980s which cut locomotive orders.

GM-EMD had previously produced 3600 hp locomotives, the SD45

EMD SD45

The EMD SD45 is a six-axle diesel locomotive built by General Motors Electro-Motive Division between December, 1965, and December, 1971. Power was provided by an EMD 645E3 twenty-cylinder engine which generated 3,600 HP. This locomotive shared the same common frame with the EMD SD38, EMD SD39, EMD...

and later SD45-2

EMD SD45-2

An EMD SD45-2 is a 6-axle diesel locomotive built by General Motors Electro-Motive Division beginning in 1972. Power was provided by an EMD 645E3 20-cylinder engine which generated . Part of the EMD Dash 2 line, the SD45-2 was an upgraded SD45.The main spotting difference between an SD45 and an...

, but these used huge, 20-cylinder

V20 engine

A V20 engine is a V engine with 20 cylinders.Engines of this number of cylinders are not common in automobiles, but this configuration is used in some large diesel engines....

engines with high fuel consumption, and had reliability problems when first introduced. Demand for the 45 series dropped sharply after the 1970s fuel crises. The SD50 used an updated version of the V16

V16 engine

A V16 engine is a V engine with 16 cylinders. Engines of this number of cylinders are uncommon in automotive use.A V16 engine is perfectly balanced regardless of the V angle without requiring counter-rotating balancing shafts which are necessary to balance Straight-4 and odd number of cylinder...

645

EMD 645

The EMD 645 family of diesel engines was designed and manufactured by the Electro-Motive Division of General Motors. Intended primarily for locomotive, marine and stationary engine use, one 16-cylinder version powered the 33-19 "Titan" prototype haul truck designed by GM's Terex...

used in the SD40-2, uprated to 3500 hp from 3000 hp. This proved to be a step too far; the 50 series models were plagued by engine problems which harmed both sales and the reputation of EMD.

The subsequent SD60

EMD SD60

model replaced the overstressed 645 engine with a new engine series, the 710

EMD 710

The EMD 710 is a line of diesel engines built by Electro-Motive Diesel . The 710 series largely replaced the earlier EMD 645 series. The EMD 710 is a large two-stroke diesel engine that has a displacement per cylinder. Since its introduction, EMD has continually upgraded the 710G diesel engine...

.

The SD50's long hood

Long hood

The long hood of a hood unit-style diesel locomotive is, as the name implies, the longer of the two hoods on a locomotive.-Equipment:...

saw changes from previous EMD models. The overall frame length was increased, and the long hood was made substantially longer. The resistors for the dynamic brake

Dynamic braking

Dynamic braking is the use of the electric traction motors of a railroad vehicle as generators when slowing the Locomotive. It is termed rheostatic if the generated electrical power is dissipated as heat in brake grid resistors, and regenerative if the power is returned to the supply line...

grid were moved from their previous location above the prime mover

Prime mover (locomotive)

In engineering, a prime mover is an engine that converts fuel to useful work. In locomotives, the prime mover is thus the source of power for its propulsion. The term is generally used when discussing any locomotive powered by an internal combustion engine...

to a new, cooler location in front of the engine compartment air intakes, where they were more effectively separated from the rest of the locomotives' systems.

Technical

The SD50 is powered by V16

V16 engine

16-645F3 series diesel engine driving either an EMD AR11A-D14 or an EMD AR16A-D18 main alternator

Alternator

An alternator is an electromechanical device that converts mechanical energy to electrical energy in the form of alternating current.Most alternators use a rotating magnetic field but linear alternators are occasionally used...

. The power generated by the main alternator drove 6 EMD D87 traction motors rated at 1170 amps each.

Depending on customer options, the SD50 was available with a multitude of traction-motor gearing ratio and wheel size options, the most common of which being the 70:17 ratio with 40 inches (1,016 mm) wheels, this allowed for a top speed of 70 mph (31.3 m/s). Other gearing options for the SD50 with 40 inches (1,016 mm) wheels include 69:18 for 76 mph (34 m/s), 67:19 for 82 mph (36.7 m/s) and 66:20 for 88 mph (39.3 m/s). 42 inch wheels were also available. Customers of the SD50 also had the option of either HT-C trucks (identified with a hydraulic shock on the side of the middle axle of each truck) or the older Flexicoil trucks, which only Conrail opted for. Some investigators had linked the HT-C truck to derailments in Amtrak's

Amtrak

The National Railroad Passenger Corporation, doing business as Amtrak , is a government-owned corporation that was organized on May 1, 1971, to provide intercity passenger train service in the United States. "Amtrak" is a portmanteau of the words "America" and "track". It is headquartered at Union...

SDP40F locomotive fleet and Conrail chose to order SD40-2's and their first order of SD50's with the older Flexicoil C truck. The controversy surrounding the HT-C truck was largely disproven, and Conrail's second order of SD50's as well as their SD60 variants were all HT-C equipped.

The SD50 could be equipped with fuel tanks sizes from 3200 gallons (12,113.3 l) up to 4400 gallons (16,655.8 l), had a lube oil capacity of 396 gallons (1,499 l) and a cooling water capacity of 276 gallons (1,044.8 l).

SD50S

The SD50S ("short frame") were prototype units built in December 1980. They were shorter than production locomotives by approximately 2 foot (0.6096 m). All of these prototypes were sold to the Norfolk & Western and passed to the Norfolk Southern; they were withdrawn in the early 2000s as non-standard. Two were rebuilt in 2008 as "SD40E" models by Norfolk Southern's Juniata Shops, along with several standard length SD50's.

The designation also applies to five locomotives built by EMD Australian licensee Clyde Engineering for Hamersley Iron

Hamersley Iron

Pilbara Iron is a wholly owned subsidiary of the multinational Rio Tinto Group, that manages assets for Hamersley Iron Pty Ltd, a wholly owned subsidiary of Rio Tinto, and Robe River Iron Associates, an unincorporated joint venture between Rio and three Japanese steel companies Mitsui Iron Ore...

. These were also shorter than production SD50s, and were equipped with a special double cab roof for insulation against the hot Australian desert sun. When withdrawn from Hamersley Iron service, they were sold to National Railway Equipment Company

National Railway Equipment Company

National Railway Equipment Company is a railroad equipment rebuilding and leasing company, headquartered in Mt. Vernon, Illinois. NREC sells rebuilt locomotives to railroad companies worldwide, with an emphasis on the North American market....

and exported to the U.S. in February 1999 and used in national lease service. They were subsequently sold to the Utah Railway

Utah Railway

The Utah Railway is a class III railroad operating in Utah and Colorado, and owned by Genesee & Wyoming Inc.-History:The Utah Railway Company was incorporated on January 24, 1912, with the name of Utah Coal Railway, shortened to Utah Railway in May of the same year...

in June 2001, where they remain.

SD50F

The SD50F was a Canadian cowl unit

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, but unlike the cab unit style, the bodywork is merely...

version equipped with a "Draper taper" (inset section aft of cab for limited rear visibility). 60 were built for the Canadian National Railway

Canadian National Railway

The Canadian National Railway Company is a Canadian Class I railway headquartered in Montreal, Quebec. CN's slogan is "North America's Railroad"....

as road numbers 5400-5459. Early engine problems resulted in a temporary down-rating to 3300 hp. Eventually the units were re-rated to 3500 hp, however they, like their U.S. cousins, continued to suffer from relatively low reliability, frequently suffering engine, power assembly, and crankshaft failures.

Original Buyers

Owner	Quantity	Numbers	Notes
Baltimore and Ohio Railroad Baltimore and Ohio Railroad The Baltimore and Ohio Railroad was one of the oldest railroads in the United States and the first common carrier railroad. It came into being mostly because the city of Baltimore wanted to compete with the newly constructed Erie Canal and another canal being proposed by Pennsylvania, which...	20	8576-8595	to CSX Transportation CSX Transportation CSX Transportation operates a Class I railroad in the United States known as the CSX Railroad. It is the main subsidiary of the CSX Corporation. The company is headquartered in Jacksonville, Florida, and owns approximately 21,000 route miles... , most have been rebuilt into SD50-2's. 14 rebuilt into SD50-3's.
Canadian National Railway	60	5400-5459	SD50F, retired
Chicago and North Western Railway	35	7000-7034	to Union Pacific, retired
Chesapeake and Ohio Railway Chesapeake and Ohio Railway The Chesapeake and Ohio Railway was a Class I railroad formed in 1869 in Virginia from several smaller Virginia railroads begun in the 19th century. Led by industrialist Collis P...	43	8553-8575, 8624-8643	to CSX Transportation CSX Transportation CSX Transportation operates a Class I railroad in the United States known as the CSX Railroad. It is the main subsidiary of the CSX Corporation. The company is headquartered in Jacksonville, Florida, and owns approximately 21,000 route miles... , most have been rebuilt into SD50-2's. 14 rebuilt into SD50-3's.
Conrail Consolidated Rail Corporation The Consolidated Rail Corporation, commonly known as Conrail , was the primary Class I railroad in the Northeast U.S. between 1976 and 1999. The federal government created it to take over the potentially profitable lines of bankrupt carriers, including the Penn Central Transportation Company and...	135	6700-6834	to CSX Transportation CSX Transportation CSX Transportation operates a Class I railroad in the United States known as the CSX Railroad. It is the main subsidiary of the CSX Corporation. The company is headquartered in Jacksonville, Florida, and owns approximately 21,000 route miles... , Norfolk Southern Railway Norfolk Southern Railway The Norfolk Southern Railway is a Class I railroad in the United States, owned by the Norfolk Southern Corporation. With headquarters in Norfolk, Virginia, the company operates 21,500 route miles in 22 eastern states, the District of Columbia and the province of Ontario, Canada... and Kansas City Southern, CSX-inherited units have been rebuilt into SD50-2's. 1 rebuilt to SD50-3 specs.
Denver and Rio Grande Western Railroad Denver and Rio Grande Western Railroad The Denver & Rio Grande Western Railroad , often shortened to Rio Grande or D&RGW, formerly the Denver & Rio Grande Railroad, is a defunct U.S. railroad company. The railroad started as a narrow gauge line running south from Denver, Colorado in 1870; however, served mainly as a transcontinental...	17	5501-5517	to Southern Pacific, to Union Pacific, retired
Kansas City Southern Railway Kansas City Southern Railway The Kansas City Southern Railway , owned by Kansas City Southern Industries, is the smallest and second-oldest Class I railroad company still in operation. KCS was founded in 1887 and is currently operating in a region consisting of ten central U.S. states...	10	703-713
Missouri Pacific Railroad Missouri Pacific Railroad The Missouri Pacific Railroad , also known as the MoPac, was one of the first railroads in the United States west of the Mississippi River. MoPac was a Class I railroad growing from dozens of predecessors and mergers, including the St. Louis, Iron Mountain and Southern Railway , Texas and Pacific...	60	5000-5059	to Union Pacific, retired
Norfolk and Western Railway Norfolk and Western Railway The Norfolk and Western Railway , a US class I railroad, was formed by more than 200 railroad mergers between 1838 and 1982. It had headquarters in Roanoke, Virginia for most of its 150 year existence....	6	6500-6505	SD50S short frame to Norfolk Southern Railway Norfolk Southern Railway The Norfolk Southern Railway is a Class I railroad in the United States, owned by the Norfolk Southern Corporation. With headquarters in Norfolk, Virginia, the company operates 21,500 route miles in 22 eastern states, the District of Columbia and the province of Ontario, Canada...
Seaboard System Railroad Seaboard System Railroad The Seaboard System Railroad was a former Class I railroad created by merging the railroads of the Family Lines System. Although sharing common ownership, the railroads of the Family Lines System used different names when conducting business...	81	8500-8552, 8596-8623	to CSX Transportation CSX Transportation CSX Transportation operates a Class I railroad in the United States known as the CSX Railroad. It is the main subsidiary of the CSX Corporation. The company is headquartered in Jacksonville, Florida, and owns approximately 21,000 route miles... , most have been rebuilt into SD50-2's. 14 rebuilt into SD50-3's.
Southern Railway	20	6506-6525	to Norfolk Southern Railway Norfolk Southern Railway The Norfolk Southern Railway is a Class I railroad in the United States, owned by the Norfolk Southern Corporation. With headquarters in Norfolk, Virginia, the company operates 21,500 route miles in 22 eastern states, the District of Columbia and the province of Ontario, Canada...

Current owners

As of 2008, current owners and operators include: