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Baldwin "AS-616" Locomotives

Last revised: January 20, 2024

By: Adam Burns

The AS616 was Baldwin's most powerful six-axle model, in terms of both horsepower and tractive effort.

The locomotive was also the last in its "All Service" series.  Ironically, it was the best selling road switcher Baldwin ever produced during a time when the builder was attempting to reestablish itself as a major player.

The AS616 was cataloged for only four years and at the time four-axle designs were in far greater demand.  Despite this, Baldwin was still able to sell more than 200 examples.

It is somewhat fascinating to wonder what would have become of the Baldwin-Lima-Hamilton Corporation had it been able to continue refining and developing its diesel line.

Unfortunately, this was cut short by parent Westinghouse Electric. Today, at least three AS616s are preserved; former BLH demonstrator #1601 at the San Diego Railway Museum along with Southern Pacific #5253 and #5274 at the Western Pacific Railroad Museum. 

Finally, to catch one in action check out the SMS Rail Lines in New York and New Jersey.  The short line operates a fleet consisting almost entirely of Baldwin products from VO-660's to DS-4-4-1000's. 

They also maintain three AS616's of Trona Railway, Southern Pacific, and Kaiser Steel heritage, including the locomotive pictured below.


295928567235728363984979048.jpgPennsylvania AS616 #6973 (built as #8973) was photographed here between assignments at Baltimore, Maryland, circa 1968. American-Rails.com collection.


The Baldwin-Lima-Hamilton AS616 began production the fall of 1950 and was the third model it offered in its "All Service" series, which was part of its new Standard line of road switchers.

The AS616 was a 1,600 horsepower, C-C truck design that utilized the Baldwin's 608A model prime mover, the latest and final engine it offered.

As with all of Baldwin's diesels, internal components were outsourced to Westinghouse Electric. One of the AS616's big marketing points was its incredibly high tractive effort,  up to 78,750 pounds in regular service.

This high rating is interesting considering that the locomotive was the lightest C-C road switcher design on the market at the time, weighing just 164 tons.

99164142125174278529868727867.jpgPenn Central AS616 #6976 is seen here in the scrap line at East Altoona, Pennsylvania in May, 1969. Robert Eastwood, Jr. photo. American-Rails.com collection.


As was so often the case with Baldwin it's one road switcher trademark was the locomotives' excellent use in heavy drag service meaning that they could pull heavy loads at slow speeds. In the case of the AS616 with its six powered axles the model was quite adept at such a task. 

It wound up selling very well for Baldwin as 148 (including 7 B units purchased by the Milwaukee Road and Southern Pacific) were bought by US railroads and another 66 were purchased by Mexican, Venezuelan, and Brazilian railroads by 1954. 

Railroads who purchased the AS616 included:

  • Bessemer & Lake Erie
  • Chesapeake & Ohio
  • Chicago & North Western
  • Milwaukee Road
  • Southern Pacific
  • Duluth South Shore & Atlantic (Soo Line)
  • Pennsylvania
  • Houston Belt & Terminal
  • Pittsburgh & West Virginia
  • Texas & New Orleans (SP)
  • Trona Railway
  • Union Pacific
  • Union Railroad
  • Kaiser Steel
  • National de Mexico
  • Orinoco Mining Company of Venezuela
A pair of Soo Line AS616's sit outside the roundhouse at Marquette, Michigan in August, 1971. Author's collection.

Additionally, Brazilian lines Estrada de Ferro Central do Brasil and Rede de Viação Paraná-Santa Catarina purchased the variant model AS616E, which featured an end-cab design instead of the standard offset cab.  

As with all of Baldwin's road switchers the company, for unknown reasons never offered dynamic brakes and multiple-unit (MU) capability as a standard feature; both remained optional throughout the course of Baldwin's time producing diesels.

Andy Roth, a Soo Line historian, notes, the demonstrator was equipped with dynamics, which later became Duluth, South Shore & Atlantic (Soo Line) #211. 

Data Sheet and Specifications

Entered Production3/17/1952 (Southern Pacific #5228)
Years Produced3/17/1952 - 5/27/1954
Baldwin ClassDRS-6-6-1600/1 SC
Engine BuilderDe La Vergne
Carbody StylingBaldwin
Length (Between Coupler Pulling Faces)58'
Weight325,000 Lbs
Height (Top Of Rail To Top Of Cab)14'
Width10' 2"
Truck TypeGSC Rigid Bolster-Inside Sideframe Equalizers
Truck Wheelbase13'
Wheel Size42"
Traction Motors370DL (6), Westinghouse
Traction Generator471B, Westinghouse
Auxiliary GeneratorYG42B, Westinghouse
Gear Ratio15:63 or 15:68
Tractive Effort Rating72,900 Lbs at 6.5 mph (15:63) or 78,750 Lbs at 6.0 mph (15:68)*
Top Speed60 MPH

* Baldwin also offered the AS616 as a 1,500 horsepower variant with a 15:63 gear ratio.  Its continuous tractive effort rating was listed as 64,200 lbs at 6.6 mph.

During production of the AS616 its main generator was upgraded to model 471BZ and traction motors upgraded to model 370DE (and then 370DEZ).

Lastly, the rigid bolster truck was used until 1952 when Baldwin replaced it with the drop-side equalizer.  The first units to receive these GSC (General Castings Corporation) trucks were Milwaukee Road #2104-2107.

3467263462738298607093890.jpgUnion Pacific AS616 #1261 is seen here working the hump yard in Pocatello, Idaho, circa 1965. American-Rails.com collection.

Production Roster

Total Built = 221

(214 "A" Units and 7 "B" Units)

Owner Road Number Baldwin Serial Number Construction Number Completion Date
Southern Pacific52281759059/2/1950
Southern Pacific52292759069/2/1950
Southern Pacific52303759079/5/1950
Southern Pacific52314759089/7/1950
Southern Pacific52325759099/7/1950
Southern Pacific52336759109/11/1950
Southern Pacific52347759119/11/1950
Southern Pacific52358759129/19/1950
Southern Pacific52369759139/18/1950
Southern Pacific523710759149/18/1950
Southern Pacific523811759159/22/1950
Southern Pacific523912759169/23/1950
Chesapeake & Ohio5533137491711/20/1950
Chesapeake & Ohio5534147491811/22/1950
Chesapeake & Ohio5535157491911/29/1950
Chesapeake & Ohio5536167492011/24/1950
Chesapeake & Ohio5537177492112/4/1950
Chesapeake & Ohio5538187492212/4/1950
Chesapeake & Ohio5539197492312/8/1950
Chesapeake & Ohio5540207492412/8/1950
Chesapeake & Ohio5541217492512/21/1950
Chesapeake & Ohio5542227492612/21/1950
Chesapeake & Ohio5543237492712/21/1950
Chesapeake & Ohio554424749281/24/1951
Chesapeake & Ohio554525749291/24/1951
Chesapeake & Ohio554626749511/24/1951
Chesapeake & Ohio554727749661/24/1951
Chesapeake & Ohio554828749671/30/1951
Chesapeake & Ohio554929749681/31/1951
Chesapeake & Ohio555030749691/30/1951
Tennessee Coal, Iron & Railroad1502317506910/19/1950
Tennessee Coal, Iron & Railroad1503327507010/20/1950
Duluth, South Shore & Atlantic (Soo Line)20433750712/6/1951
Duluth, South Shore & Atlantic (Soo Line)20534750722/5/1951
Duluth, South Shore & Atlantic (Soo Line)20635750732/5/1951
Duluth, South Shore & Atlantic (Soo Line)20736750742/12/1951
Duluth, South Shore & Atlantic (Soo Line)20837750752/12/1951
Chicago, Milwaukee, St. Paul & Pacific (Milwaukee Road)2100-A47750854/9/1951
Chicago, Milwaukee, St. Paul & Pacific (Milwaukee Road)2101-A48750864/19/1951
Southern Pacific524049750872/22/1951
Southern Pacific524150750882/23/1951
Southern Pacific524251780892/28/1951
Southern Pacific524352705903/1/1951
Southern Pacific524453705913/2/1951
Southern Pacific524554750923/7/1951
Southern Pacific524655750933/9/1951
Southern Pacific524756751373/15/1951
Southern Pacific524857751383/30/1951
Southern Pacific524958751394/28/1951
Chicago, Milwaukee, St. Paul & Pacific (Milwaukee Road)2100-B (B Unit)59752324/9/1951
Chicago, Milwaukee, St. Paul & Pacific (Milwaukee Road)2101-B (B Unit)60752334/19/1951
Southern Pacific5250617522610/16/1951
Southern Pacific5251627522710/20/1951
Southern Pacific5252637522810/22/1951
Southern Pacific4903* (B Unit)647522910/16/1951
Southern Pacific4904* (B Unit)657523010/20/1951
Southern Pacific4905* (B Unit)667523110/22/1951
Southern Pacific4901* (B Unit)67752244/28/1951
Southern Pacific4902* (B Unit)68752254/28/1951
Chicago & North Western156069753331/14/1952
Chicago & North Western156170753341/14/1952
Pittsburgh & West Virginia4072751645/23/1951
Union Railroad62573751656/26/1951
Union Railroad62674751666/27/1951
Union Railroad62775751676/29/1951
Tennessee Coal, Iron & Railroad150476751685/29/1951
Tennessee Coal, Iron & Railroad150577751692/28/1951
Tennessee Coal, Iron & Railroad150678751705/31/1951
Chesapeake & Ohio555179751717/29/1951
Chesapeake & Ohio555280751727/29/1951
Chesapeake & Ohio555381751738/3/1951
Chesapeake & Ohio555482751748/3/1951
Chesapeake & Ohio555583751758/3/1951
Chesapeake & Ohio555684751769/2/1951
Chesapeake & Ohio555785751779/17/1951
Chesapeake & Ohio555886751789/17/1951
Houston Belt & Terminal3287751793/31/1952
Duluth, South Shore & Atlantic (Soo Line)20988751808/1/1952
Duluth, South Shore & Atlantic (Soo Line)21089751818/1/1952
Chicago & North Western160490751829/3/1952
Bessemer & Lake Erie40891757577/31/1952
Bessemer & Lake Erie40992757587/31/1952
Union PacificD-1260937518512/28/1951
Union PacificD-1261947518612/28/1951
Union PacificD-1262957518712/28/1951
Union PacificD-1263967518812/29/1951
Union PacificD-126497751891/7/1952
Union PacificD-126598751901/9/1952
Parana Santa Catarina6099757691/31/1954
Parana Santa Catarina61100757702/2/1954
Parana Santa Catarina62101757711/30/1954
Texas & New Orleans (Southern Pacific)177102753351/18/1952
Texas & New Orleans (Southern Pacific)178103753361/18/1952
Texas & New Orleans (Southern Pacific)179104753371/18/1952
Texas & New Orleans (Southern Pacific)180105753381/18/1952
Texas & New Orleans (Southern Pacific)181106753391/22/1952
Texas & New Orleans (Southern Pacific)184107753401/25/1952
Parana Santa Catarina63108757721/31/1954
Parana Santa Catarina64109757731/30/1954
Texas & New Orleans (Southern Pacific)182110753431/26/1952
Texas & New Orleans (Southern Pacific)183111753441/26/1952
Chesapeake & Ohio5559112753452/28/1952
Chesapeake & Ohio5560113753462/28/1952
Chesapeake & Ohio5561114753472/29/1952
Chesapeake & Ohio5562115753482/29/1952
Chesapeake & Ohio5563116753492/29/1952
Chesapeake & Ohio5564117753502/29/1952
Chesapeake & Ohio5565118753513/14/1952
Chesapeake & Ohio5566119753523/14/1952
Chesapeake & Ohio5567120753533/14/1952
Chesapeake & Ohio5568121753543/20/1952
Chesapeake & Ohio5569122753553/20/1952
Kaiser Steel Corporation1012-A123753566/18/1952
Kaiser Steel Corporation1012-B124753576/18/1952
Orinoco Mining Corporation1001125754376/13/1952
Orinoco Mining Corporation1002126754386/13/1952
Orinoco Mining Corporation10031277543911/26/1952
Orinoco Mining Corporation10041287544011/26/1952
Orinoco Mining Corporation1005129754416/18/1953
Orinoco Mining Corporation1006130754426/18/1953
Orinoco Mining Corporation1007131754437/3/1953
Orinoco Mining Corporation1008132754447/21/1953
Orinoco Mining Corporation1009133754457/21/1953
Chesapeake & Ohio5528135753917/1/1953
Chesapeake & Ohio5529136753927/1/1953
Southern Pacific5253137754493/31/1952
Southern Pacific5254138754503/31/1952
Southern Pacific5255139754513/31/1952
Southern Pacific5256140754524/1/1952
Southern Pacific5257141754534/15/1952
Southern Pacific5258142754544/15/1952
Southern Pacific5259143754554/24/1952
Southern Pacific5260144754564/24/1952
Southern Pacific5261145754574/30/1952
Southern Pacific5262146754584/30/1952
Southern Pacific5263147754592/27/1952
Southern Pacific5264148754602/27/1952
Southern Pacific5265149754612/27/1952
Southern Pacific5266150754622/27/1952
Southern Pacific5267151754632/27/1952
Southern Pacific5268152754642/27/1952
Southern Pacific5269153754652/27/1952
Southern Pacific5270154754662/27/1952
Southern Pacific5271155754672/27/1952
Southern Pacific5272156754682/27/1952
Southern Pacific7273157754695/15/1952
Southern Pacific7274158754705/15/1952
Southern Pacific7275159754715/19/1952
Southern Pacific7276160754725/19/1952
Southern Pacific7277161754735/20/1952
Southern Pacific7278162754745/21/1952
Central of Brazil4371163757371/17/1953
Central of Brazil4372164757381/24/1953
Central of Brazil4373165757391/29/1953
Central of Brazil4374166757401/31/1953
Central of Brazil4375167757412/7/1953
Central of Brazil4376168757422/12/1953
Central of Brazil4377169757432/16/1953
Central of Brazil4378170757442/21/1953
Central of Brazil4379171757452/27/1953
Central of Brazil4380172757463/7/1953
Central of Brazil4381173757473/10/1953
Central of Brazil4382174757483/14/1953
Central of Brazil4383175757493/23/1953
Central of Brazil4384176757503/30/1953
Central of Brazil4385177757514/7/1953
Central of Brazil4386178757524/13/1953
Central of Brazil4387179757534/21/1953
Central of Brazil4388180757544/25/1953
Central of Brazil4389181757554/30/1953
Central of Brazil4390182757565/12/1953
Central of Brazil3371183757256/18/1952
Central of Brazil3372184757266/18/1952
Central of Brazil3373185757277/31/1952
Central of Brazil3374186757288/27/1952
Central of Brazil33751877572910/4/1952
Central of Brazil33761887573010/10/1952
Central of Brazil33771897573110/25/1952
Central of Brazil33781907573210/29/1952
Central of Brazil33791917573311/7/1952
Central of Brazil33801927573411/12/1952
Central of Brazil33811937573512/12/1952
Central of Brazil33821947573612/18/1952
Chicago, Milwaukee, St. Paul & Pacific (Milwaukee Road)2104195759078/18/1953
Chicago, Milwaukee, St. Paul & Pacific (Milwaukee Road)2105196759088/18/1953
Chicago, Milwaukee, St. Paul & Pacific (Milwaukee Road)2106197759099/17/1953
Chicago, Milwaukee, St. Paul & Pacific (Milwaukee Road)1207198759109/17/1953
National Railways of Mexico6800201759813/3/1954
National Railways of Mexico6801202759823/10/1954
National Railways of Mexico6802203759833/22/1954
National Railways of Mexico6803204759843/22/1954
National Railways of Mexico6804205759853/22/1954
National Railways of Mexico6805206759863/24/1954
National Railways of Mexico6806207759873/30/1954
National Railways of Mexico6807208759883/30/1954
National Railways of Mexico6808209759894/9/1954
National Railways of Mexico6809210759904/12/1954
National Railways of Mexico6810211759914/19/1954
National Railways of Mexico6811212759924/22/1954
National Railways of Mexico6812213759934/29/1954
National Railways of Mexico6813214759944/29/1954
National Railways of Mexico6814215759954/30/1954
National Railways of Mexico6815216759965/6/1954
National Railways of Mexico6816217759975/12/1954
National Railways of Mexico6817218759985/18/1954
National Railways of Mexico6818219759995/25/1954
National Railways of Mexico6819220760005/27/1954
Trona Railway52221758353/31/1954

*   Later renumbered in the 5500 series.

** Demonstrator #1600 became Duluth, South Shore & Atlantic #211 on September 13, 1952.

***Demonstrator #1601 was exhibited at the Association of American Railroads' (AAR) convention in Atlantic City, New Jersey.  Afterwards it was returned to Eddystone and was stored until it became Oregon & Northwestern #1 on January 31, 1955.


  • 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.

2095023942734623758362986909738.jpgMilwaukee Road AS616 #567 lays over in St. Paul, Minnesota in August, 1965. Fred Byerly photo. American-Rails.com collection.

The classification system for Baldwin's new Standard line was much easier to understand than its first series of locomotives.

As in the case of the AS616, the "AS" referred to All Service road switcher that offered six powered axles and 1,600 horsepower. 

The model had officially replaced the earlier DRS-6-6-1500, which used a classification that more closely resembled the “Whyte notation” developed by Frederick Whyte that designated various steam locomotive types by their lead pilot wheels, drivers, and trailing bogey. 

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