EMD SD50

EMD SD50
An SD50 operated byKansas City Southern Railway
Type and origin Power type Diesel-electric Builder Electro-Motive Diesel General Motors Diesel Clyde Engineering Model SD50 Build date December 1980 – July 1987 Total produced 431
Specifications Gauge 4 ft8+1⁄2in(1,435 mm)standard gauge Length 71 ft 2 in (21.69 m) over thecouplerpulling faces Prime mover EMD16-645F3B Engine type V16diesel Alternator main:AR11 Cylinders 16
Performance figures Power output 3,500hp(2,610 kW) at 950 rpm; increased to 3,600hp(2,685 kW) November 1984.
Career Operators SeeOriginal buyers Disposition Some in service, some retired, one preserved

TheEMD SD50is a 3,500-horsepower(2,610 kW)diesel-electric locomotivebuilt byGeneral Motors Electro-Motive Division.It was introduced in May 1981 as part of EMD's "50 Series"; production ceased in January 1986. The SD50 was a transitional model between EMD'sDash 2series which was produced throughout the 1970s and themicroprocessor-equippedSD60andSD70locomotives. A total of 431 were built.

History

The SD50 was produced in response to increasingly tough competition fromGE Transportation,whoseDash 7line was proving quite successful with railroads. While EMD'sSD40-2was a reliable and trusted product, GE's line included locomotives up to 3,600 hp (2,685 kW) 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.

The GM-EMD locomotives that immediately preceded the SD50, the 3,600 hp (2,685 kW)SD45andSD45-2,used huge,20-cylinderengines that consumed large amounts of fuel and suffered from reliability problems when first introduced. Demand for the 45 series dropped sharply after the 1970s fuel crisis. The SD50 used an updated version of theV16645from the SD40-2, uprated to 3,500 hp (2,600 kW) at 950rpmfrom 3,000 hp (2,240 kW) at 900 rpm, and uprated again in November 1984 to 3,600 hp (2,685 kW). This proved to be a step too far; the 50 series models were plagued by engine and electrical system problems which harmed EMD's sales and reputation.

Compared with their predecessors, the SD50 had a longer frame and a substantially longerlong hood.In addition, the resistors for thedynamic brakegrid were moved from their location on previous models above theprime moverto a new, cooler location in front of the engine compartment air intakes, closer to the electrical switchgear. This increased their separation from other systems, simplifying maintenance for the prime mover and the electrical system.

One former SD50 engineer praised the locomotives'wheel-slip controlsystem and dynamic braking power, stating "they were able to give more adhesion than aSD40-2".

Technical

The SD50 is powered byV1616-645F3 series diesel engine driving either an EMD AR11A-D14 or an EMD AR16A-D18 tractionalternator.The power generated by the traction alternator drove 6 EMD D87traction motorsrated at 1170 amps each.

The SD50 was available with multiple traction motor gearing ratios and wheel sizes, the most common of which was the 70:17 ratio with 40-inch (1,016 mm) wheels, which allowed for a top speed of 70 mph (110 km/h). Other gearing options for the SD50 with 40-inch (1,016 mm) wheels included 69:18 for 76 mph (122 km/h), 67:19 for 82 mph (132 km/h) and 66:20 for 88 mph (142 km/h). The SD50 was also available with 42-inch (1,067 mm) wheels.

The SD50 was also available with either HT-C trucks (identified with a hydraulic shock on the side of the middle axle of each truck) or the earlierFlexicoil trucks.Some investigators implicated the HT-C truck in derailments ofAmtrak'sSDP40Fs,soConrailchose the Flexicoil C trucks for their SD40-2s and their first order of SD50s—the only customer to do so. The controversy surrounding the HT-C truck was eventually disproved, and Conrail chose HT-C trucks for their second order of SD50s and SD60s.

SD50S

TheSD50S( "short frame" ) were prototype units built in December 1980. They were shorter than production locomotives by approximately 2 feet (0.61 m). There were six SD50Ss built, all of which were sold to theNorfolk & Westernand eventually passed toNorfolk Southern.They were withdrawn in the early 2000s as non-standard. Two were rebuilt in 2008 as "SD40E" models by Norfolk Southern'sJuniata Shops,along with several standard length SD50s.

NS SD50#5443 (EX-CR #6776)

The SD50S designation was also used for five locomotives built by EMD Australian licenseeClyde Engineering,AdelaideforHamersley Iron.Shorter than production SD50s, they were equipped with a special double cab roof for insulation against the hot Australian desert sun in thePilbararegion. Withdrawn in November 1995, they were sold toNational Railway Equipment Companyand exported to the United States in February 1999 and used in national lease service.They were subsequently sold to theUtah Railwayin June 2001.In June 2017, 6063 and 6064 were sold to theChicago, Fort Wayne & Eastern Railroad,6064 was relocated byGenesee & Wyomingto theIndiana & Ohio Railwayand renumbered 5016 and 5017.

SD50F

TheSD50Fwas a Canadiancowl unitversion equipped with a "Draper taper" (inset section aft of cab for limited rear visibility). Sixty were built for theCanadian National Railwayas road numbers 5400–5459. Early engine problems resulted in a temporary down-rating to 3,300 horsepower (2,500 kW). Eventually the units were re-rated to 3,500 horsepower (2,600 kW); however, like their U.S. cousins, they continued to suffer from relatively low reliability, frequently suffering engine, power assembly, and crankshaft failures.

CN SD50F#5438

Original owners

Railroad	Qty.	Road numbers	Notes	References
SD50
Baltimore & Ohio (Chessie System)	20	8576–8595
Chicago & North Western	35	7000–7034	7009donated to theIllinois Railway Museum
Chesapeake & Ohio (Chessie System)	43	8553–8575, 8624–8643
Conrail	135	6700–6834
Denver & Rio Grande Western	17	5501–5517
Kansas City Southern Railway	10	704–713
Missouri Pacific Railroad	60	5000–5059
Seaboard System Railroad	81	8500–8552, 8596–8623
Norfolk Southern	20	6506–6525
Hamersley Iron	5	6060–6064
SD50S
Norfolk & Western Railway	6	6500–6505	SD50S short frame
SD50F
Canadian National	60	5400–5459	Cowl units
Totals	431

Rebuilds

A number of SD50s have been rebuilt into the equivalent ofSD40-2s.TheDash 2features are already contained within the SD50. The units are derated from 3,500 hp (2,600 kW) at 950 rpm to 3,000 hp (2,200 kW) at 900 rpm. This is actually a quite simple change to the locomotive'sWoodwardPGE engine governor.

Preservation

• In late October 2022, theIllinois Railway Museumacquired formerChicago & North Western #7009,believed by the museum to be the first preserved SD50.

See also

• List of GM-EMD locomotives
• List of GMD Locomotives
• Chicago and North Western 7009

External links

Media related toEMD SD50 locomotivesat Wikimedia Commons

• Lytle, Stan.EMD SD50 list.Retrieved 16 February 2005.
• TrainWeb.The Unofficial EMD homepage.Retrieved 7 January 2005. Contains fairly complete builders' records for EMD production.
• Union Pacific Railroad Locomotive Department (1994).Locomotive Diagram Book.Union Pacific.
• Electo-Motive Division of General Motors (1980).SD50 Operator's Manual 1st Edition November 1980.Electro-Motive Diesel.