Baldwin “Centipede” Locomotives: Specs, Roster, Photos

Last revised: September 24, 2026

Baldwin’s Centipede was a 91-foot diesel with twelve axles and the ride of an electric. The catalog name is DR-12-8-1500/2, also written DR-12-8-3000: diesel road locomotive, twelve axles, eight of them motored, two De La Vergne 608SC engines at 1,500 horsepower each. Seaboard Air Line asked for it. The railroad wanted 6,000 horsepower from two units on a 2-D+D-2 wheel arrangement. Baldwin built the production fleet from December 3, 1945 (Seaboard 4500) through July 20, 1948 (Ferrocarriles Nacionales de México 6413). Fifty-two locomotives were sold, to the Seaboard, the Pennsylvania, and the NdeM. Two more, finished for a cancelled Union Pacific order, stayed on the builder’s account. All were scrapped.

The 1943 test bed is the same locomotive as Seaboard 4500. Baldwin finished demonstrator 6000 that May with four of eight planned engines in the carbody, stored it, and in 1944 Seaboard officers found it at Eddystone. The frame, cab, and running gear were rebuilt around two 608SC engines. This page is that machine: the test bed, the 3,000-horsepower catalog model, John F. Kirkland’s account of it, and the 54-line production roster.

Seaboard Air Line DR-12-8-3000 Centipede 4500 in Florida in early December 1945 before Jacksonville to St. Petersburg service

Seaboard Air Line Centipede #4500 in Florida in early December 1945, shortly before it entered service between Jacksonville and St. Petersburg. This is the rebuilt 1943 demonstrator 6000. American-Rails.com collection.

On this page: At a glance · Essl’s test bed · What the name means · Who bought them · John Kirkland’s comments · A dual-mode study · On the Pennsylvania · Gearing · Data sheets · Production roster · What became of them

At a glance

Item	Detail
Builder	Baldwin Locomotive Works, Eddystone, Pennsylvania. De La Vergne engines. Westinghouse generators and traction motors
Catalog model	DR-12-8-1500/2, also DR-12-8-3000. Baldwin class DR 12-8-1500/2 SC-1. Baby Face carbody
Wheel arrangement	2-D+D-2. Two unpowered axles, four motored, articulation, four motored, two unpowered
Engines	Two 608SC straight-eights, Roots-blown, 1,500 hp each, 3,000 hp. Oil-fired steam generator
1943 test bed	Demonstrator 6000. Class 4-8+8-4 750/8 DE1. Construction 64639. Eight Model 408s planned at 750 hp; four installed. Completed May 28, 1943. Rebuilt as Seaboard 4500
Size and weight	91 ft 6 in over coupler pulling faces. 15 ft to the cab roof. 10 ft 4¾ in wide. Production weight 595,000 lb. The 1943 unit weighed 685,000 lb
Production	December 3, 1945 – July 20, 1948. Baldwin serials 1–54. 52 sold (Seaboard 14, NdeM 14, Pennsylvania 24). Two demonstrators never sold
Pennsylvania	12 drawbar pairs, 5823A1/A2–5834A1/A2, class BP60. Later numbered 5811–5834 and reclassed BH50 for helper service
Preserved	All scrapped

Specifications follow John F. Kirkland, The Diesel Builders, Volume III: Baldwin Locomotive Works (Interurban Press, 1994), as carried on this page’s data sheets. Information compiled September 24, 2026.

Essl’s test bed, and a Seaboard request

Baldwin drew the Centipede as a passenger locomotive. The wheel arrangement is the diesel answer to a ride the Pennsylvania had already bought in electric form. In 1934 the railroad tested prototypes on its electrified line at Claymont, Delaware. The winner was the GG1, a 2-C+C-2, and Baldwin built a large share of the production fleet. A decade later Seaboard wanted that tracking in a diesel for the Florida lines.

Charles A. Brown’s May 1982 Trains article starts the diesel side of the story with Max Essl and a locomotive built around several small engine-generator sets. The hardware was demonstrator 6000. Baldwin ordered the eight engines on May 27, 1940. The War Production Board cleared completion in 1942. Class 4-8+8-4 750/8 DE1, construction number 64639, was to carry eight De La Vergne Model 408s at 750 horsepower and 1,050 rpm, 6,000 horsepower in one carbody, Westinghouse 370A motors, a 488C main generator, 25:54 gearing, and a 120 mph top speed. Weight on Kirkland’s sheet is 685,000 pounds. Delays and cost stopped the work in the spring of 1943 with four engines installed. Baldwin called the locomotive complete on May 28, 1943, and tried it on the Pennsylvania, the Reading, and the Baltimore & Ohio around Philadelphia.

The plant worked. A single 6,000-horsepower passenger unit offered less redundancy than an A-B-A of three 2,000-horsepower locomotives, which is what Electro-Motive and Alco were selling, and Baldwin could not build the eight-engine carbody at a profit. A freight version of the same idea, drawn at 4,500 horsepower with lower gearing, stayed on the drawing board. No. 6000 went into storage at Eddystone.

Baldwin experimental DR-12-8-3000 Centipede demonstrator 6000 of 1943 designed for eight 750-horsepower engines

Baldwin’s experimental Centipede, demonstrator #6000, completed May 28, 1943. The design called for eight 750-horsepower De La Vergne Model 408 engines. Four were installed. The frame, cab, and running gear later became Seaboard Air Line #4500.

Kirkland’s account of the next step is the one to keep. In 1944 Seaboard officers touring Eddystone came across the stored 2-D+D-2. They wanted the wheel arrangement, and they wanted 6,000 horsepower split across two locomotives. Baldwin rebuilt 6000 with its then-current 608SC, two engines at 1,500 horsepower, Roots blowers, an oil-fired steam generator, and Westinghouse 370F motors on a 471A main generator. The new class was DR-12-8-1500/2. Completed on December 3, 1945, under a new construction number, 71579, it still carried 6000 for a moment and then became Seaboard Air Line 4500. It went into passenger service on December 13, 1945, Jacksonville to St. Petersburg, geared 21:58, good for 93.5 mph. Seaboard ordered thirteen more.

Baldwin builder photo of new Seaboard Air Line Centipede 4500 at Eddystone Pennsylvania after completion on December 3 1945

Baldwin builder photograph of new Seaboard Air Line #4500 at Eddystone after completion on December 3, 1945. The locomotive entered Jacksonville–St. Petersburg service on December 13.

What DR-12-8-3000 means

The 2-D+D-2 is electric notation, which is the right family for this running gear. A “2” is a pair of unpowered axles. “D” is four motored axles, the same alphabet that makes a B a two-motor truck and a C a three-motor truck. The plus sign is the articulation between the two halves. Eight Westinghouse traction motors, twelve axles, and a guided truck at each end: that is the GG1 idea carried into a diesel, with one more motored axle on each half.

Baldwin’s own string reads the same locomotive from the catalog. DR is Diesel Road. The 12 is every axle. The 8 is the motored axles. The 3000 is the horsepower. The builder’s longer form, DR-12-8-1500/2, spells the same fact as two engines of 1,500 horsepower. Later Baldwin model codes shortened the horsepower to two digits, so a 2,000-horsepower Baby Face is a DR-6-4-20. The Centipede kept the full number in one of its names and the split rating in the other. Both appear on the data sheets below. They are one model.

Three buyers, and two locomotives that never sold

Seaboard’s result was public enough that the orders came quickly. The Pennsylvania took twelve semi-permanently coupled pairs, 24 locomotives, at $287,250 each. The 24-unit order came to $6,894,000. The first pair, 5823A1 and 5823A2, was completed on April 17, 1947, geared 22:57, with a 100 mph passenger rating. As delivered they were class BP60: Baldwin passenger, 6,000 horsepower for the pair. Each pair shared a construction number, with A1 and A2 suffixes. The railroad later split the drawbars for couplers and numbered the units individually as 5811–5834.

Pennsylvania Railroad Centipede set with 5832 closest to the camera at West Philadelphia on January 7 1958

A Pennsylvania Centipede set at West Philadelphia on January 7, 1958, with #5832 closest to the camera. By this date the fleet was in the individually numbered 5811–5834 series. American-Rails.com collection.

Ferrocarriles Nacionales de México took fourteen, 6400–6413. Baldwin’s serial 2, NdeM 6400, was completed April 15, 1947. Serial 3, NdeM 6401, was completed January 10, 1948, and the last of the Mexican units, 6413, left Eddystone on July 20, 1948, the last Centipede completed. Kenneth L. Douglas’s companion article in the May 1982 Trains is the Mexican chapter: high-altitude service, and a 1953 return to Baldwin for overhaul. The last of them were still at work in 1971.

Ferrocarriles Nacionales de Mexico Centipede 6401 outshopped by Baldwin in early 1948

Ferrocarriles Nacionales de México Centipede #6401, completed January 10, 1948. César Martínez Ávila collection.

Union Pacific ordered a pair as 998 and 999 and cancelled it. Baldwin finished the locomotives on March 16, 1948, construction numbers 73129 and 73130, and showed them as demonstrators 6000 (the second locomotive to carry that number) and 6001. Kirkland notes that they went out geared 15:63, the freight ratio, so a railroad could watch the tracking with only eight motors. They remained demonstrators and were parted out.

John Kirkland’s comments

John F. Kirkland worked at Baldwin from 1940 until the company left the locomotive business. The Diesel Builders, Volume III: Baldwin Locomotive Works (Pasadena: Interurban Press, 1994) is his record of that work, and the Centipede passage below is his. The production roster and the specification sheets on this page follow the same book.

Baldwin considered the Centipede an optional model which was offered as an alternate to conventional locomotive models where track conditions made such a wheel arrangement highly desirable.

Baldwin felt there might be a demand for this locomotive equipped with traction motors on all 12 axles for use in heavy drag operations. Had it been so equipped it would have, in effect, functioned like a six traction motored 3,000 horsepower road switcher coupled to a six traction motored slug.

This was one of the premises that prompted placing demonstrators numbers 6000 and 6001 on the road equipped with 15:63 freight gearing. In this manner the general design of this model, together with its unexcelled tracking characteristics, could be observed by potential customers, even though it was equipped with only eight traction motors.

The reception given by the railroads in the 1945-1950 period to these Baldwin Centipedes was essentially the same as that given to the big high-horsepower dual engine equipped locomotives that were introduced to the trade again in the mid-1960s by Alco, EMD, and GE.

Summed up in a few words, they did not possess the flexibility that was inherent when obtaining the same horsepower through the use of two smaller locomotives operating in multiple unit. Whereas there were three purchasers of Centipedes, 20 years later there were only two purchasers of big dual engine equipped locomotives.

One of the three articles on Centipedes that appears in a well read railfan magazine was devoted to discussing the “Engineering faux pas” built into the Pennsylvania Railroad’s 12 pairs of locomotives.

Adverse comment was offered about their poor tracking characteristics; lack of dynamic brake; inability to multiple with any other type of locomotive of any make other than themselves, and then only when coupled back-to-back; difficulty of changing out worn brake shoes; problems with the engines due to operation over mountainous terrain; and excessive piston ring and cylinder liner wear, together with excessive lube oil consumption.

This type of negative commentary would have been spoiled had the facts relating to these purported deficiencies been presented. To support this assertion, some facts, rather than opinions, will be offered.

The rest of the chapter is that rebuttal, and the book is the place to read it in full. Dynamic brakes and multiple-unit control were options on the Centipede, as they were on Baldwin’s other diesels. The Pennsylvania’s brake-shoe complaint followed from shops that lacked an inspection pit for this running gear. The Seaboard built the pits. A GG1 was maintained from the same kind of pit, and the Pennsylvania already owned more than a hundred of those. The derailments came when the Centipedes were placed mid-train, or behind a freight as pushers. The torque, and the outside rail of a curve, did the damage. Seaboard kept its Centipedes on the head end. Electric trouble, lubrication trouble, and engine fires on the Pennsylvania’s passenger assignments were real, and they are a separate list from the tracking argument.

A dual-mode study that stayed on paper

While the Centipede was in production, the Denver & Rio Grande Western studied a freight version that could run as a diesel or as a straight electric. The territory was the Moffat Route, Denver to Bond via the Moffat Tunnel, 129 miles, and 54 miles in Utah between Thistle and Helper. Under the wire the leading and trailing axles would have been motored as well, a B-D+D-B, at 6,000 horsepower for one unit and 12,000 for a pair. Off the wire the end axles would have idled, as on a production Centipede. It was the same impulse that later produced Electro-Motive’s FL9, applied to a mountain freight railroad. The locomotives stayed on paper. A dual-mode machine on Baldwin engines and Westinghouse electrical gear was a product Alco and General Electric, the partners a joint project would have required, had little reason to help the other two firms sell.

On the Pennsylvania

The Pennsylvania bought the Centipede for the head end of passenger trains. Class BP60, 22:57 gearing, 100 mph. Within a few years electrical trouble and lubrication trouble, sometimes an engine fire, took them off those assignments. By 1951 the drawbars had been replaced with couplers and the gearing changed to 15:63: 65 mph, and 85,600 pounds of continuous tractive effort at 10.5 mph on Baldwin’s gear table. The railroad reclassed them BH50. That class is the helper rating, 2,500 horsepower per unit, 5,000 for a pair. They went to work as pushers on westbound freights between Altoona and Gallitzin, over Horseshoe Curve, the service the running gear was least suited to. In 1958 many moved to helper jobs between Altoona and Enola. At least one worked as the Paoli pusher.

Pennsylvania Railroad Centipede 5822 and a second Centipede on a westbound freight at Altoona Pennsylvania in July 1960 David Sweetland

Pennsylvania #5822 and a second Centipede on a westbound freight at Altoona, Pennsylvania, July 1960, photographed from the 8th Street Bridge. The number is the individual series applied after the railroad split the drawbar pairs. David Sweetland photo.

William Volkmer’s chapter in the same May 1982 Trains is the Pennsylvania personality piece, written by a man who liked the locomotive. The mechanical department’s verdict was colder. Before the fleet was retired, the railroad looked at stripping the engines and rebuilding the carbodies as straight electrics. Great Northern was disposing of its Cascade Tunnel motors in the mid-1950s, and the Pennsylvania bought those. On the Pennsylvania they were class FF2, covered with the rest of the electric classes on the electric roster. The Centipedes were out of revenue service by the early 1960s. The last of them were at scrap in 1964.

Gearing options

Baldwin offered the production model with a choice of gear ratios. Seaboard 4500 was delivered at 21:58. The Pennsylvania’s passenger pairs were 22:57, and the helper conversion was 15:63. The 25:54 row is the 120 mph option. It is a production figure. The 1943 test bed also carried 25:54 gearing, and Kirkland’s sheet for that heavier locomotive, with 370A motors, rates it at 45,000 pounds at 39 mph. The two ratings belong to two power plants.

Gear ratio	Maximum speed (mph)	Continuous tractive effort (lb)	Speed at that rating (mph)
15:63	65	85,600	10.5
19:60	82	64,400	14.0
21:58	93.5	56,200	16.0
22:57	100	52,800	17.6
23:56	106	49,600	18.8
25:54	120	44,000	20.6

Data sheets and specifications

Experimental demonstrator 6000 (1943)

Item	Specification
Engines ordered	May 27, 1940
Date completed	May 28, 1943
Baldwin class	4-8+8-4 750/8 DE1
Construction number	64639
Engine	Model 408, eight at 750 hp (four installed)
Engine builder	De La Vergne
Supercharger	Roots
Steam generator	Oil-fired
Horsepower	6,000 designed
Engine speed	1,050 rpm
Length over coupler pulling faces	91 ft 6 in
Height, rail to cab roof	15 ft
Width	10 ft 4¾ in
Weight	685,000 lb
Trucks	2-D+D-2
Wheel size	40 in
Traction motors	Westinghouse 370A, eight
Traction generator	Westinghouse 488C
Auxiliary generator	Westinghouse YG37B
Gear ratio	25:54
Tractive effort	45,000 lb at 39 mph
Top speed	120 mph

Seaboard Air Line 4500, the rebuilt demonstrator

No. 4500 reused the 1943 frame and running gear, and Kirkland’s sheet keeps that unit’s 40-inch wheels. The catalog specification further down the page gives the production model 42-inch wheels.

Item	Specification
Date completed	December 3, 1945
Baldwin class	DR 12-8-1500/2 SC-1
Construction number	71579
Engine	608SC, two
Engine builder	De La Vergne
Supercharger	Roots
Steam generator	Oil-fired
Horsepower	3,000
Length over coupler pulling faces	91 ft 6 in
Height, rail to cab roof	15 ft
Width	10 ft 4¾ in
Weight	595,000 lb
Trucks	2-D+D-2
Wheel size	40 in
Traction motors	Westinghouse 370F, eight
Traction generator	Westinghouse 471A
Auxiliary generator	Westinghouse YG42A
Gear ratio	21:58
Continuous tractive effort	56,200 lb at 16 mph
Top speed	93.5 mph

Cataloged model

Item	Specification
Entered production	December 3, 1945 (Seaboard Air Line 4500)
Years produced	December 3, 1945 – July 20, 1948
Baldwin class	DR 12-8-1500/2 SC-1
Engine	608SC, two
Engine builder	De La Vergne
Supercharger	Roots
Steam generator	Oil-fired
Horsepower	3,000
Length over coupler pulling faces	91 ft 6 in
Height, rail to cab roof	15 ft
Width	10 ft 4¾ in
Weight	595,000 lb
Trucks	2-D+D-2
Wheel size	42 in
Traction motors	Westinghouse 370F, eight
Traction generator	Westinghouse 471A
Auxiliary generator	Westinghouse YG42A
Gear ratio	Optional. See the table above

Production roster

Total on the Baldwin serial list = 54. Fifty-two were sold. The table follows Kirkland’s Baldwin serial number, which is the model sequence. Completion dates and construction numbers follow their own sequences. Pennsylvania pairs share one construction number, distinguished by the A1 and A2 suffixes. NdeM is Ferrocarriles Nacionales de México. The 1943 test bed is Seaboard 4500.

Owner	Road number	Baldwin serial	Construction number	Completed
Seaboard Air Line	4500	1	71579	12/3/1945
NdeM	6400	2	72672	4/15/1947
NdeM	6401	3	72673	1/10/1948
NdeM	6402	4	72674	4/21/1948
NdeM	6403	5	72675	5/4/1948
NdeM	6404	6	72676	5/9/1948
NdeM	6405	7	72677	5/14/1948
NdeM	6406	8	72678	5/21/1948
NdeM	6407	9	72679	5/31/1948
NdeM	6408	10	72680	6/13/1948
NdeM	6409	11	72681	7/8/1948
NdeM	6410	12	72682	7/8/1948
NdeM	6411	13	72683	7/9/1948
NdeM	6412	14	72684	7/18/1948
NdeM	6413	15	72685	7/20/1948
Baldwin (demonstrator)	6000 (2nd)	16	73129	3/16/1948
Baldwin (demonstrator)	6001	17	73130	3/16/1948
Pennsylvania	5823A1	18	73131A1	4/17/1947
Pennsylvania	5823A2	19	73131A2	4/17/1947
Seaboard Air Line	4501	20	73141	3/15/1947
Seaboard Air Line	4502	21	73142	4/9/1947
Seaboard Air Line	4503	22	73143	4/22/1947
Seaboard Air Line	4504	23	73144	5/11/1947
Seaboard Air Line	4505	24	73145	5/18/1947
Pennsylvania	5824A1	25	73377A1	5/10/1947
Pennsylvania	5824A2	26	73377A2	5/10/1947
Pennsylvania	5825A1	27	73378A1	6/15/1947
Pennsylvania	5825A2	28	73378A2	6/15/1947
Pennsylvania	5826A1	29	73379A1	9/5/1947
Pennsylvania	5826A2	30	73379A2	9/5/1947
Pennsylvania	5827A1	31	73380A1	10/15/1947
Pennsylvania	5827A2	32	73380A2	10/15/1947
Pennsylvania	5828A1	33	73381A1	11/15/1947
Pennsylvania	5828A2	34	73381A2	11/15/1947
Pennsylvania	5829A1	35	73382A1	12/20/1947
Pennsylvania	5829A2	36	73382A2	12/20/1947
Pennsylvania	5830A1	37	73383A1	1/17/1948
Pennsylvania	5830A2	38	73383A2	1/17/1948
Pennsylvania	5831A1	39	73384A1	1/31/1948
Pennsylvania	5831A2	40	73384A2	1/31/1948
Pennsylvania	5832A1	41	73385A1	2/7/1948
Pennsylvania	5832A2	42	73385A2	2/7/1948
Pennsylvania	5833A1	43	73386A1	2/18/1948
Pennsylvania	5833A2	44	73386A2	2/18/1948
Pennsylvania	5834A1	45	73387A1	2/28/1948
Pennsylvania	5834A2	46	73387A2	2/28/1948
Seaboard Air Line	4506	47	73146	6/10/1947
Seaboard Air Line	4507	48	73147	7/26/1947
Seaboard Air Line	4508	49	73390	9/25/1947
Seaboard Air Line	4509	50	73391	9/28/1947
Seaboard Air Line	4510	51	73392	11/22/1947
Seaboard Air Line	4511	52	73393	12/4/1947
Seaboard Air Line	4512	53	73394	12/28/1947
Seaboard Air Line	4513	54	73395	1/4/1948

Demonstrators 6000 (2nd) and 6001 were ordered by the Union Pacific as 998 and 999. The order was cancelled. The locomotives were never sold, and were parted out. Seaboard 4500’s construction number, 71579, is the 1945 rebuild. The 1943 test bed was construction number 64639.

What became of them

Seaboard kept its fourteen in road service for close to fifteen years and was done with them by the early 1960s. The Pennsylvania’s twenty-four lasted about as long in calendar years and a much shorter time in the job they were bought for. Revenue use was over by the early 1960s, and the last of the carbodies were at scrap in 1964. NdeM sent its units back to Baldwin in 1953 for overhaul and upgrades, and the last of that fleet ran until 1971. The two demonstrators stayed Baldwin’s and were parted out. Every Centipede was scrapped.

The locomotive remains what Kirkland said it was: an optional model, for a railroad that wanted this wheel arrangement, bought by three companies when the trade was already deciding that the same horsepower was more useful in two smaller units. The Pennsylvania then asked it to push. The tracking story that followed is the story of that assignment.

Sources

Kirkland, John F. The Diesel Builders, Volume III: Baldwin Locomotive Works. Pasadena: Interurban Press, 1994. Specification sheets, gear table, production roster, and the Centipede commentary quoted above
Brown, Charles A. “The Centipede Connection — 1: From Essl’s Effort to Seaboard’s Solution.” Trains, Vol. 42, No. 7 (May 1982), pp. 38–45
Douglas, Kenneth L. “The Centipede Connection — 2: The Mexican Experience, Low Performance at High Altitude.” Trains, Vol. 42, No. 7 (May 1982), pp. 46–47
Volkmer, William. “The Centipede Connection — 3: Personality on the Pennsy, Why Baldwin’s Biggest Was My Favorite Diesel.” Trains, Vol. 42, No. 7 (May 1982), pp. 48–50
Pinkepank, Jerry A. Diesel Spotter’s Guide. Milwaukee: Kalmbach, 1967
Schafer, Mike, and Brian Solomon. Pennsylvania Railroad. Osceola: MBI, 1997
Solomon, Brian. Baldwin Locomotives. Minneapolis: Voyageur Press, 2009

Facebook X Pinterest Tumblr Reddit WhatsApp Messenger