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Baldwin "VO-660" Locomotives

Last revised: June 23, 2023

By: Adam Burns

The VO660 was Baldwin's first diesel switcher model, debuting in 1939 along with its more powerful cousin, the VO-1000.

It somewhat resembled models then in production by the American Locomotive and Electro-Motive Corporation.

The Baldwin Locomotive Works was slow to embrace the diesel-electric concept as a main line locomotive. 

However, as John Kirkland points out in his book, "The Diesel Builders: Volume Three (Baldwin Locomotive Works," Baldwin was quite familiar with electric and diesel-electric technology dating back to the early 20th century.

Between 1910-1926, Baldwin constructed more than 1,230 gasoline-engine switchers and in 1925 built its first diesel-powered locomotive.

Today, a few examples of the VO-660 remain preserved; Wyandotte Terminal #103 is located at the Illinois Railway Museum while Standard Steel #6712 is currently being put back into operation by short line SMS Lines (which loves Baldwins and rosters several in active service).


3648289035872376398893479009849.jpgChicago & North Western VO-660m #1237, circa 1965. This unit was outshopped by Baldwin on April 28, 1945. It was sent to Electro-Motive in the late 1950s and rebuilt with a 567C power plant. American-Rails.com collection.


The VO660 began production in April, 1939 as the company's first true diesel model. The company was able to produce its own line of diesels only after it had acquired the I.P. Morris & De La Vergne company, which specialized in the design and construction of diesel engines.

Interestingly, Baldwin's purchase of the company was more to diversify its holdings in offering switcher and light duty diesels, as it saw no need to develop a main line freight or passenger locomotive. This can also be seen in its 1929 purchase of the Whitcomb Locomotive Works, which dated back to the late 19th century.

Whitcomb began specializing in electric/diesel-electric locomotives as early as 1914 and after Baldwin's purchase continued to release small, industrial size switchers that actually sold relatively well.

Despite Baldwin's later issues of remaining competitive in the diesel market it actually found sustained business in small switchers.  

Seen here is Youngstown Sheet & Tube Company VO-660 #607 on June 2, 1984, preserved at the Illinois Railway Museum in Union. L.S. Melin photo/Arnold Morscher collection.

The "VO" was the designation De La Vergne gave to the prime mover used in the locomotive and the "660" simply regarded the horsepower.

The company kept this setup through the VO1000 but soon after changed its classification system to a complex set of numbers and letters.  

While Baldwin only sold a little over 100 VO660s railroads tended to favor the design, as could be seen in later models that sold several hundred units.

Class I railroads like the Denver & Rio Grande Western, Chicago & North Western, New York Central, Northern Pacific, Western Maryland, Reading, Wabash and others all purchased at least a few examples of the VO660.

The relatively good reliability of the small switcher and its rugged pulling power made it a real favorite among crews and railroads.   

Data Sheet and Specifications

Baldwin's early "VO" model switchers are somewhat difficult to differentiate in that the builder was slowly phasing production over to diesel technology.  As a result, its early variants were offered in a variety of horsepower ratings and constructed at the same time.

The information presented here will break down the switchers built to the 660 horsepower rating, and the various differences to which each was constructed until Baldwin settled on a standardized design.

Baldwin technically never classified the model as the "VO-660."  As Brian Solomon notes in his book, "Baldwin Locomotives," this was another railfan designation to classify these early switchers. 

In truth, Baldwin never gave its first production switcher line any name at all, only listing them by their horsepower rating.

The first built to 660 horsepower (and Baldwin's third diesel-electric it ever produced) was demonstrator #62000; despite changes here and there this locomotive essentially kicked off the 660 horsepower line.

Demonstrator #62000

Date Built10/1936
Baldwin Class8-OE-660/1 E-1*
EngineVO, 6-Cylinder In-Line
Engine BuilderDe La Vergne
Carbody StylingBaldwin
Length (Between Coupler Pulling Faces)39' 6"
Weight212,000 Lbs.
Truck TypeRigid Bolster, Drop-Side Equalizer
Truck Wheelbase8'
Wheel Size40"
Traction MotorsAllis-Chalmers Manufacturing Company
Traction GeneratorAllis-Chalmers Manufacturing Company
Auxiliary GeneratorAllis-Chalmers Manufacturing Company
Gear Ratio16:76
Tractive Effort Rating29,900 Lbs at 5.7 MPH.
Top Speed45 MPH

* Baldwin's classification system:

  • 8 = Total number of wheels
  • OE = Oil engine-Electric transmission
  • 660/1 = One 660 HP engine
  • E = 4 pairs of driving wheels
  • 1 = First locomotive of this class

From Baldwin's view, #62000 was its first production diesel locomotive, completed as a demonstrator in October, 1936.  Following demonstrations on June 28, 1937 it was sold to the Santa Fe as #2200.  The locomotive primarily handled switching chores at AT&SF's Dearborn Station (Chicago).

In 1940 Baldwin offered to replace the locomotive with a 1,000 horsepower variant (Class 0-4-4-0 1000/1 DE29), which featured Westinghouse equipment, a trait by then shared with all Baldwin-produced diesels.

The Santa Fe accepted #2206 on May 29, 1941; #2200 was returned to Baldwin and became Eddystone plant switcher #1.  It was eventually sold to Boston Metals Company in the 1960's and scrapped in 1966.

Reading #36

Completion Date6/22/1939
Baldwin Class8-DE-660/1 E-1*
EngineVO, 6-Cylinder In-Line
Engine BuilderDe La Vergne
Carbody StylingBaldwin
Length (Between Coupler Pulling Faces)43' 8"
Weight194,000 Lbs.
Truck TypeBatz
Truck Wheelbase8' 4"
Wheel Size40"
Traction Motors362 (4), Westinghouse
Traction Generator485D2, Westinghouse
Auxiliary GeneratorYG30B, Westinghouse
Gear Ratio16:76
Tractive Effort Rating28,000 Lbs at 6.5 MPH.
Top Speed45 MPH

* Baldwin's updated classification system:

  • 8 = Total number of wheels
  • DE = Diesel-Electric
  • 660/1 = One 660 HP engine
  • E = 4 pairs of driving wheels
  • 1 = First locomotive of this class

Reading #36 (later renumbered 60 within a year of its delivery) was a one-off design that featured 'I' beams between the engine compartment running the length of the carbody.  

This resulted in an extended pilot "porch" and unconventional elevated walkway along the long hood.  No other VO-660's were built like this particular unit.

Early Variants

Completion Date12/5/1939 (Demonstrator #299*)
Years Produced12/5/1939-2/1940
Baldwin Class8-DE-660/1 E
EngineVO, 6-Cylinder In-Line
Engine BuilderDe La Vergne
Carbody StylingBaldwin
Length (Between Coupler Pulling Faces)45'
Weight198,500 Lbs.
Height (Top Of Rail To Top Of Cab)14' 6"
Truck TypeBatz
Truck Wheelbase8'
Wheel Size40"
Traction Motors362 (4), Westinghouse
Traction Generator485H2, Westinghouse
Auxiliary GeneratorYG30C, Westinghouse
Gear Ratio16:76
Tractive Effort Rating28,000 Lbs at 6.5 MPH.
Top Speed45 MPH

*  Baldwin demonstrator #299, completed on December 5, 1939, was the first VO-660 to carry the  now classic-lines of its switcher series.

Later Variants

Completion Date5/20/1940 (Northern Pacific #128)
Years Produced5/20/1940-6/15/1946
Baldwin Class8-DE-660/1 E
EngineVO, 6-Cylinder In-Line
Engine BuilderDe La Vergne
Carbody StylingBaldwin
Length (Between Coupler Pulling Faces)45'
Weight198,500 Lbs.
Height (Top Of Rail To Top Of Cab)14' 6"
Truck TypeRigid Bolster, Drop-Side Equalizer*
Truck Wheelbase8'
Wheel Size40"
Traction Motors362B (4), Westinghouse
Traction Generator485H2, Westinghouse
Auxiliary GeneratorYG30C, Westinghouse
Gear Ratio16:76
Tractive Effort Rating28,000 Lbs at 6.5 MPH.
Top Speed45 MPH

* As John Kirkland notes in his book, "The Diesel Builders: Volume Two," General Steel Casting Corporation never gave their trucks model identifications, such as AAR Type A or AAR Type B. 

While the types were adopted by American Association of Railroads (AAR) as standard designs, their specific designations were actually coined by railfans, not the industry. 

Production Roster

Total Built = 141

Later Variants

Owner Road Number Baldwin Serial Number Construction Number Completion Date
Northern Pacific128 (Renumbered 650)6623925/20/1940
Chicago, Milwaukee, St. Paul & Pacific (Milwaukee Road)16357623935/19/1940
Minneapolis, Northfield & Southern6008623946/9/1940
Terminal Railroad Association Of St. Louis5319623957/23/1940
Terminal Railroad Association Of St. Louis53210623967/24/1940
Missouri Pacific900911623979/3/1940
Missouri Pacific901012623989/12/1940
Elgin, Joliet & Eastern27116624883/19/1941
Elgin, Joliet & Eastern27217624893/19/1941
Seaboard Air Line120218624902/10/1941
American Steel & Wire119624914/17/1941
Southern Pacific102120624924/15/1941
Southern Pacific102221624934/15/1941
New York Central50122624945/7/1941
Iowa Ordnance Depot2-10023624955/29/1941
Denver & Rio Grande Western6624624965/31/1941
Wabash Railway20025624977/28/1941
Missouri Pacific920626624986/26/1941
Upper Merion & Plymouth5127624997/21/1941
Missouri Pacific901228625007/25/1941
Denver & Rio Grande Western6729625017/20/1941
Denver & Rio Grande Western6830625027/17/1941
Denver & Rio Grande Western6931641838/4/1941
Denver & Rio Grande Western7032641848/8/1941
Denver & Rio Grande Western7133641858/18/1941
Denver & Rio Grande Western7234641868/19/1941
Denver & Rio Grande Western7335641879/5/1941
Denver & Rio Grande Western7436641888/30/1941
Patapsco & Back Rivers6337641898/21/1941
Western Maryland1201396419110/6/1941
Southern RailwayDS-2005436419510/10/1941
New Orleans Public Belt41446419610/24/1941
Nashville, Chattanooga & St. Louis40456419711/5/1941
Louisville & Nashville20466423011/26/1941
Louisville & Nashville21476423112/7/1941
Louisville & Nashville22486423212/18/1941
Louisville & Nashville23496423312/3/1941
New York Central50250642341/16/1942
Central Railroad Of New Jersey104051642351/22/1942
Central Railroad Of New Jersey104152642361/22/1942
Central Railroad Of New Jersey104253642371/26/1942
Central Railroad Of New Jersey104354642381/27/1942
Terminal Railroad Association Of St. Louis53355642392/22/1942
Terminal Railroad Association Of St. Louis53456642403/1/1942
New Orleans Public Belt4257642413/11/1942
New Orleans Public Belt4358642423/12/1942
Upper Merion & Plymouth5259642432/28/1942
Akron & Barberton Belt2560642443/18/1942
Northern Pacific12961642454/10/1942
Northern Pacific13062642464/7/1942
Upper Terminal Of Memphis909064642484/16/1942
Upper Terminal Of Memphis909165642494/5/1942
Basic Magnesium, Inc.100066642504/19/1942
Patapsco & Back Rivers6467642514/11/1942
Patapsco & Back Rivers6568642524/1/1942
St. Louis-San Francisco60069642535/3/1942
St. Louis-San Francisco60170642545/7/1942
American Steel & Wire23-171643877/2/1942
Western Maryland10372643887/18/1942
Western Maryland10473643897/13/1942
Chicago & Eastern Illinois11076643928/28/1942
Minneapolis, Northfield & Southern178643949/24/1942
New York Central752806439610/22/1942
New York Central753816439711/2/1942
New York Central754826439811/2/1942
Western Maryland10584644009/15/1942
Westinghouse Electric & Manufacturing Company1092647576/9/1942
U.S. Navy15937032412/30/1944
U.S. Navy16947032512/29/1944
U.S. Navy18957032612/28/1944
New York Central75596703271/2/1945
New York Central75697703281/2/1945
New York Central75798703291/5/1945
New York Central75899703301/6/1945
New York Central759100703311/10/1945
New York Central760101703321/10/1945
New York Central761102703331/10/1945
Youngstown Sheet & Tube600103717592/15/1945
Youngstown Sheet & Tube601104717603/19/1945
U.S. Navy10105720024/26/1945
U.S. Navy11106720034/26/1945
U.S. Navy31107720045/16/1945
Youngstown Sheet & Tube602108715124/25/1945
Youngstown Sheet & Tube603109715134/24/1945
Chicago & North Western1237110715144/28/1945
Chicago & North Western1238111715154/28/1945
Chicago & North Western1239112715165/11/1945
Youngstown Sheet & Tube604113715175/30/1945
Youngstown Sheet & Tube605114715185/30/1945
Chicago & North Western1240115715196/7/1945
Chicago & North Western1241116715206/7/1945
Chicago & North Western1242117715216/8/1945
Chicago & North Western1243118715696/14/1945
Chicago & North Western1244119715706/16/1945
Chicago & North Western1245120715716/18/1945
Chicago, St. Paul, Minneapolis & Omaha (C&NW)58121715726/25/1945
Chicago, St. Paul, Minneapolis & Omaha (C&NW)59122715736/28/1945
Chicago, St. Paul, Minneapolis & Omaha (C&NW)68123715746/28/1945
Chicago & North Western1246124715758/13/1945
Youngstown Sheet & Tube606125715768/20/1945
Youngstown Sheet & Tube607126715779/17/1945
Long Island Rail Road4031277157810/2/1945
American Smelting & Refining19501287281311/2/1945
American Smelting & Refining19511297281410/29/1945
American Smelting & Refining19521307281511/4/1945
American Smelting & Refining19531317281611/5/1945
Warner Company111327281711/30/1945
Francisco Sugar Company45133728186/15/1946
Proctor & Gamble Company1251347281912/26/1945
American Steel & Wire11135728201/9/1946
Wyandotte Terminal Railroad1011387282310/30/1945
Singer Manufacturing Company21397282411/24/1945
Wyandotte Terminal Railroad1021407282511/28/1945
Wyandotte Terminal Railroad1031417282611/28/1945
LaSalle & Bureau County6143728281/24/1946
Kansas City Southern1150144728295/8/1946

Beginning with Baldwin's "B Lot" of VO-660's, the first of which was serial number 16 (Elgin, Joliet & Eastern #271), the cab roof was lowered from 14' 6" to 14'. 

This was made to improve clearance restrictions under bridges, within tunnels, and among other potential obstacles.  In total, the VO-660 was built in Lots A through K; changes after Lot B were minor.

Early Variants

Owner Road Number Baldwin Serial Number Construction Number Completion Date
Baldwin Demonstrator62000 (Became Santa Fe #2200)16200010/1936
Santa Fe2200 (Traded to Baldwin on 5/29/1941; became plant switcher #1.)16200010/1936
Reading36 (Renumbered 60)1623006/22/1939
Baldwin Demonstrator299 (Plant switcher)26229912/5/1939
Baldwin Demonstrator335 (Sold to Standard Steel Works [#12] on 2/24/1940, later renumbered 6712.)3623351/31/1940
Baldwin Demonstrator336 (Sold to Elgin, Joliet & Eastern [#270] on 5/7/1940.)4623363/1940
Baldwin Demonstrator337 (Sold to Central of Georgia [#5])5623372/1940

Of important note is the first five VO-660's constructed, Baldwin serial numbers 1-5; these locomotives were built to the specifications noted above. 

Beginning with Baldwin serial #6 (Northern Pacific #128), part of "Lot A" (Baldwin's way of designating minor differences/improvements to a model type), some changes were made which is reflected in the below data sheet.  


  • Foster, Gerald. A Field Guide To Trains. New York: Houghton Mifflin, 1996.
  • Kirkland, John F. Diesel Builders, The:  Volume Three, Baldwin Locomotive Works. Pasadena: Interurban Press, 1994.
  • Pinkepank, Jerry A. Diesel Spotter's Guide.  Milwaukee: Kalmbach Publishing Company, 1967.
  • Solomon, Brian.  Baldwin Locomotives.  Minneapolis:  Voyageur Press, 2009.

Standard Steel VO-660 #6712 is seen here at the company's plant in Burnham, Pennsylvania on July 20, 1976. Purchased new by the manufacturer in 1940 she is the oldest preserved Baldwin, currently owned by SMS Rail. Doug Kroll photo.


The VO660 also found an interest with industrial settings as companies like the Iowa Ordnance Plant, American Smelting and Refining Company, American Steel & Wire Company and even the US Navy and Westinghouse itself purchased the VO660. 

For Baldwin its real successes with switcher designs came later with models like the VO-1000, S12, and DS-4-4-1000. These locomotives offered much greater horsepower and tractive effort, which made them more marketable (as railroads could employ them in a number of different applications, not just switching and shuffling cars). 


Wes Barris's SteamLocomotive.com is simply the best web resource on the study of steam locomotives. 

It is difficult to truly articulate just how much material can be found at this website. 

It is quite staggering and a must visit!