View source for EMD SD50

{{More footnotes needed|date=December 2021}}

{{Short description|American diesel-electric locomotive}}

{{Use dmy dates|date=December 2021}}
{{Infobox locomotive
| name = EMD SD50
| caption = An SD50 operated by [[Kansas City Southern Railway]]
| powertype = Diesel-electric
| uicclass = [[Co'Co']]
| gauge = {{track gauge|1435 mm}}
| length = {{convert|71|ft|2|in|abbr=on}}
| image = EMD SD50.JPG
| gear ratio = 70:17
| multipleworking = Yes
| locobrakes = [[Westinghouse air brake|Westinghouse]], [[Dynamic braking|Dynamic brake]]
| trainbrakes = [[Railway air brake|Air braked]]
| maxspeed = {{Convert|70|mph|km/h|abbr=on}}
| poweroutput = {{convert|3500|hp|abbr=on|lk=in|sigfig=3}} at 950 rpm; increased to {{convert|3600|hp|abbr=on|lk=in|sigfig=4}} November 1984.
| buildmodel = SD50
| builder = [[Electro-Motive Diesel]]<br>[[General Motors Diesel]]<br>[[Clyde Engineering]]
| builddate = December 1980 – July 1987
| fueltype = [[Diesel fuel|Diesel]]
| fuelcap = {{Convert|3,500|gal|liter|abbr=on}}
| lubecap = {{Convert|283|gal|liter|abbr=on}}
| coolantcap = {{Convert|250|gal|liter|abbr=on}}
| sandcap = {{Convert|56|cuft|liter|abbr=on}}
| primemover = [[Electro-Motive Diesel|EMD]] [[EMD 645|16-645F3B]]
| rpmrange max = 950
| enginetype = [[V16 engine|V16]] [[Diesel engine|diesel]]
| aspiration = [[Turbocharger|Turbocharged]]
| cylindercount = 16
| transmission = [[Diesel-electric]]
| alternator = ''main'' : AR16/D18 (3,500), AR11 (3,600)
| tractionmotors = EMD 87Y (3,500), EMD 87A (3,600)
| totalproduction = 431
| operator = See [[EMD SD50#Original buyers|Original buyers]]
| disposition = Some in service, some retired, one preserved
}}

The '''EMD SD50''' is a {{convert|3500|hp|lk=in|sigfig=3|adj=on}} [[diesel-electric locomotive]] built by [[Electro-Motive Diesel|General 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's [[EMD Dash 2|Dash 2]] series which was produced throughout the 1970s and the [[microprocessor]]-equipped [[EMD SD60|SD60]] and [[EMD SD70|SD70]] locomotives. A total of 431 were built.<ref>{{Cite magazine |date=May 2005 |title=Coming to Terms With EMD's SD50 |magazine=Trains Magazine |pages=24–25}}</ref>

==History==
The SD50 was produced in response to increasingly tough competition from [[GE Transportation]], whose [[GE Dash 7 Series|Dash 7]] line was proving quite successful with railroads. While EMD's [[EMD SD40-2|SD40-2]] was a reliable and trusted product, GE's line included locomotives up to {{convert|3600|hp|abbr=on|sigfig=4}} 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 {{convert|3600|hp|abbr=on|sigfig=4}} [[EMD SD45|SD45]] and [[EMD SD45-2|SD45-2]], used huge, [[V20 engine|20-cylinder]] engines 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 the [[V16 engine|V16]] [[EMD 645|645]] from the SD40-2, uprated to {{convert|3500|hp|abbr=on}} at 950 [[Revolutions per minute|rpm]] from {{convert|3000|hp|abbr=on|sigfig=3}} at 900 rpm, and uprated again in November 1984 to {{convert|3600|hp|abbr=on|sigfig=4}}. 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 longer [[long hood]]. In addition, the resistors for the [[dynamic braking|dynamic brake]] grid were moved from their location on previous models above the [[Prime mover (locomotive)|prime mover]] to 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 slide protection|wheel-slip control]] system and dynamic braking power, stating "they were able to give more adhesion than a [[EMD SD40-2|SD40-2]]".<ref name=":0" />

==Technical==
The SD50 is powered by [[V16 engine|V16]] 16-645F3 series diesel engine driving either an EMD AR11A-D14 or an EMD AR16A-D18 traction [[alternator]]. The power generated by the traction alternator drove 6 EMD D87 [[traction motors]] rated 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 {{convert|40|in|mm|0|adj=on}} wheels, which allowed for a top speed of {{convert|70|mph|abbr=on}}. Other gearing options for the SD50 with {{convert|40|in|mm|0|adj=on}} wheels included 69:18 for {{convert|76|mph|abbr=on}}, 67:19 for {{convert|82|mph|abbr=on}} and 66:20 for {{convert|88|mph|abbr=on}}. The SD50 was also available with {{convert|42|in|mm|0|adj=on}} 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 earlier [[Flexicoil truck]]s. Some investigators implicated the HT-C truck in derailments of [[Amtrak]]'s [[EMD SDP40F|SDP40Fs]], so [[Conrail]] chose 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==
The '''SD50S''' ("short frame") were prototype units built in December 1980. They were shorter than production locomotives by approximately {{convert|2|ft|m}}. There were six SD50Ss built, all of which were sold to the [[Norfolk & Western]] and eventually passed to [[Norfolk Southern]]. They were withdrawn in the early 2000s as non-standard. Two were rebuilt in 2008 as "SD40E" models by Norfolk Southern's [[Altoona Works|Juniata Shops]], along with several standard length SD50s.
[[File:NS Loco No.5443.jpg|thumb|NS 5443, an SD50]]
The SD50S designation was also used for five locomotives built by EMD Australian licensee [[Clyde Engineering]], [[Adelaide]] for [[Hamersley & Robe River railway|Hamersley Iron]].<ref>Super Series Locomotives for Hamersley Iron ''[[Network (periodical)|Network]]'' February 1981 page 27</ref> Shorter than production SD50s, they were equipped with a special double cab roof for insulation against the hot Australian desert sun in the [[Pilbara]] region. Withdrawn in November 1995, they were sold to [[National Railway Equipment Company]] and exported to the United States in February 1999 and used in national lease service.<ref>Hammersley Loco Update ''[[Railway Digest]]'' November 1998 pages 33, 36</ref> They were subsequently sold to the [[Utah Railway]] in June 2001.<ref>Here & There ''[[Australian Railway History|Australian Railway Historical Society Bulletin]]'' issue 771 January 2002 page 32</ref><ref>{{cite book|last=Oberg|first=Leon|title=Locomotives of Australia 1850s-2010s|year=2010|publisher=Rosenberg Publishing|location=Kenthurst|isbn=9781921719011|pages=390–391}}</ref> In June 2017, 6063 and 6064 were sold to the [[Chicago, Fort Wayne & Eastern Railroad]], 6064 was relocated by [[Genesee & Wyoming]] to the [[Indiana & Ohio Railway]] and renumbered 5016 and 5017.<ref>Motive Power Roundup ''[[Motive Power]]'' issue 119 September 2018 page 104</ref>

==SD50F==
The '''SD50F''' was a Canadian [[cowl unit]] version equipped with a "Draper taper" (inset section aft of cab for limited rear visibility). Sixty were built for the [[Canadian National Railway]] as road numbers 5400–5459.  Early engine problems resulted in a temporary down-rating to {{convert|3300|hp}}.  Eventually the units were re-rated to {{convert|3500|hp}}; however, like their U.S. cousins, they continued to suffer from relatively low reliability, frequently suffering engine, power assembly, and crankshaft failures.
[[File:BCRAIL SB coal train Clolell, BC with CN 5438 September 14, 1987 (22777697471).jpg|thumb|CN 5438, an SD50F]]

{{clear}}

==Original owners==
{{unreferenced section|date=December 2021}}
{| class=wikitable
!Railroad
!Qty.
!Road numbers
!Notes
!References
|-
! colspan="5" | SD50
|- align=center
|[[Baltimore & Ohio]]<br>([[Chessie System]])
|20
|8576–8595
| align=left |
|
|- align=center
|[[Chicago & North Western]]
|35
|7000–7034
| align=left | [[Chicago and North Western 7009|7009]] donated to the [[Illinois Railway Museum]]
|<ref name=":0" />
|- align = "center"
|[[Chesapeake and Ohio Railway|Chesapeake & Ohio]]<br>([[Chessie System]])
|43
|8553–8575, 8624–8643
| align=left |
|
|- align = "center"
|[[Conrail]]
|135
|6700–6834
| align=left |
|
|- align = "center"
|[[Denver & Rio Grande Western]]
|17
|5501–5517
| align=left |
|
|- align = "center"
|[[Kansas City Southern Railway]]
|10
|704–713
| align=left |
|
|- align = "center"
|[[Missouri Pacific Railroad]]
|60
|5000–5059
| align=left |
|
|- align="center"
|[[Seaboard System Railroad]]
|81
|8500–8552, 8596–8623
| align=left |
|
|- align="center"
|[[Norfolk Southern]]
|20
|6506–6525
| align=left |
|
|- align="center"
|[[Hamersley & Robe River railway|Hamersley Iron]]
|5
|6060–6064
| align=left |
|
|-
! colspan="5" |SD50S
|- align = "center"
|[[Norfolk & Western Railway]]
|6
|6500–6505
| align=left | SD50S short frame
|
|-
! colspan="5" |SD50F
|- align="center"
|[[Canadian National]]
|60
|5400–5459
| align=left |Cowl units
|
|-
!Totals !! 431 !! !! !!
|}

==Rebuilds==
A number of SD50s have been rebuilt into the equivalent of [[EMD SD40-2|SD40-2]]s. The ''Dash 2'' features are already contained within the SD50. The units are derated from {{convert|3500|hp|abbr=on}} at 950 rpm to {{convert|3000|hp|abbr=on}} at 900 rpm. This is actually a quite simple change to the locomotive's [[Woodward Inc|Woodward]] PGE engine governor.

==Preservation==
•&nbsp;In late October 2022, the [[Illinois Railway Museum]] acquired former [[Chicago and North Western 7009|CNW 7009]], believed by the museum to be the first preserved SD50.<ref name=":0">{{cite web |last=Smedley |first=Steve |date=November 2, 2022 |title=Illinois Railway Museum acquires SD50 |url=https://www.trains.com/trn/news-reviews/news-wire/illinois-railway-museum-acquires-sd50/ |access-date=November 3, 2022 |website=Trains Magazine}}</ref>

==See also==
* [[List of GM-EMD locomotives]]
* [[List of GMD Locomotives]]
* [[Chicago and North Western 7009]]

==References==
{{Reflist}}

==External links==
{{commons category-inline|EMD SD50 locomotives}}
* Lytle, Stan. ''[https://web.archive.org/web/20050228001453/http://www.trainnet.org/Libraries/Lib006/EMDSD50.TXT EMD SD50 list]''. Retrieved 16 February 2005.
* TrainWeb.com. ''[http://www.trainweb.org/emdloco/index.html The Unofficial EMD homepage]''. Retrieved 7 January 2005. Contains fairly complete builders' records for EMD production.
* {{cite book | author = Union Pacific Railroad Locomotive Department| title = Locomotive Diagram Book| publisher = [[Union Pacific]] | year = 1994}}
* {{cite book | author = Electo-Motive Division of General Motors| title = SD50 Operator's Manual 1st Edition November 1980| publisher = [[Electro-Motive Diesel]] | year = 1980}}

{{EMD cab and cowl}}
{{EMD SDs}}
{{CN Cowls}}

[[Category:C-C locomotives]]
[[Category:Clyde Engineering locomotives]]
[[Category:Diesel–electric locomotives of the United States]]
[[Category:Diesel locomotives of Western Australia]]
[[Category:Electro-Motive Division locomotives|SD50]]
[[Category:Freight locomotives]]
[[Category:General Motors Diesel locomotives|SD50]]
[[Category:Railway locomotives introduced in 1980]]
[[Category:Standard-gauge locomotives of the United States]]
[[Category:Standard-gauge locomotives of Canada]]
[[Category:Standard-gauge locomotives of Australia]]
[[Category:Diesel–electric locomotives of Australia]]
[[Category:Baltimore and Ohio locomotives]]
[[Category:Canadian National Railway locomotives]]
[[Category:Chesapeake and Ohio locomotives]]
[[Category:Chicago and North Western Railway locomotives]]
[[Category:Conrail locomotives]]
[[Category:Denver and Rio Grande Western Railroad locomotives]]
[[Category:Norfolk Southern Railway locomotives]]