Union Pacific Fairbanks-Morse Erie Builts

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The page was last updated on October 13, 2018.

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(Portions of this article were previously published in "The Streamliner", Volume 15, Number 1, Winter 2001)


Union Pacific Authority For Expenditure (AFE) 282, dated August 31, 1945, says this: "Purchase one 6,000 horsepower combination freight and passenger locomotive (three units) from Fairbanks-Morse. Price $600,000. For Salt Lake City to Los Angeles service."

Because FM did not have the production capacity at its plant in Beloit, Wisconsin, the units were built by General Electric under contract at GE's Erie, Pennsylvania, factory, hence the "Erie-built" nickname. F-M accepted the order as its LD6, the sixth locomotive to be built by this new builder. F-M's fourth locomotive order (LD4) was a switcher for Union Pacific, completed in May 1945 as UP D.S.1300 (the D.S. prefix meaning Diesel Switch).

This set of two Erie-built cab units and a single booster unit was delivered in December 1945 as UP 50-M, with the three units (A-B-A) sub-numbered as 50-M-1A, 50-M-3B, and 50-M-2A. The M suffix stood for Motor, and fell in line with the road's other diesel power, with numbers such as 5-M for its E3s, and 7-M to 9-M for its E6s.

UP's Erie-built units were the first of the model to be completed. A later note attached to the AFE states that the units were geared too high for freight service, but too low for passenger service, and that they were converted to 104 mph gearing for passenger service. The purchase was approved based on satisfactory performance in high-speed passenger service. These units were delivered in late December 1945, and converted to passenger service in May 1946. FM eventually built a total of 54 Erie-built locomotives for railroads in the U.S., including eight cab units and five booster units for UP.

UP's first Fairbanks-Morse locomotives were an A-B-A set of Erie-built passenger units, the 50-M set delivered in December 1945. A single 1,000-horsepower yard switcher was also delivered 1945, as D.S. 1300, with D.S. denoting "Diesel Switch". In November 1947, the road acquired four more Erie-built passenger units -- two cab units (UP 984A and 985A) and two booster units (UP 986B and 987B). In March and April 1948, four more cab units were delivered, as UP 704-707, along with two more booster units, as UP 704B and 706B, bringing the total Erie-built fleet to eight cab units and five booster units.


At the dawn of the post World War II era, Union Pacific was at a crossroads in its motive power design. Its highly successful 4-8-4 Northerns, 4-6-6-4 Challengers, and 4-8-8-4 Big Boys were the peak in the road's steam locomotive design. But all of the road's competitors were finding and documenting lower operating and maintenance costs by using diesel-electric locomotives in road service. Union Pacific's top management was growing uncomfortable with the image the road was getting for sticking with its steam locomotive designs. The use of diesel locomotives was being seen by the investment community as being modern, and the road's management in Omaha was feeling some pressure from the Board of Directors in New York to join the ranks of modern railroads.

UP began looking for ways to modernize and reduce the costs of its motive power. With all of its competitors seeming to be rushing head-long into full dieselization, the road began looking for a route that would most benefit from the diesels' economy of both operation and maintenance. The route selected was the former Los Angeles & Salt Lake line between Salt Lake City, Utah, and Los Angeles, California.

The road had sufficient experience with the peak horsepower needed for its fast freight operations, with its most recent tests of a Big Boy showing that a general figure of 6,000 horsepower was needed to move a train of 3,600 trailing tons. Big Boys were tested between Salt Lake City and Lynndyl, and additional Big Boys were even considered for the desert run. What kept big, modern steam away from the LA&SL (or more properly, the South-Central District)? Water, or lack of it. And what little water there was, was full of alkaline and other dissolved minerals. Steam locomotives need a lot of water, preferably, clean, sweet water, and the LA&SL's water was anything but sweet and clean.

Although this may sound pretty bad, for its current steam operations on the South-Central District, UP had the water situation under control, but at a high cost. The cost of locomotive fuel was also a deciding factor. Instead of cheap Wyoming coal, the route used fuel oil from the Los Angeles basin. An oil burning Big Boy on the South-Central District would need an massive tender, possibly longer than the locomotive itself. Had the district been the home of higher traffic levels, the cost of adding more and better water treatment plants and fueling stations would have been justified, as it was when UP almost totally rebuilt the Wyoming mainline and engine facilities in 1941 to accommodate the Big Boys there. The cost of fuel, and the cost of water treatment are what brought the first road diesels to Union Pacific.

As World War II was ending, the nation's railroads had little to choose from as a range of diesel-electric road freight locomotives. This lack of acceptable designs was soon discovered by UP. Many historians have remarked on the lack of innovative locomotive design during the war years, putting the blame on the War Production Board for its restrictions. In fact, the so-called WPB restrictions were largely voluntary based on each builder's ability to produce locomotives, and their ability to fill orders both from the railroads, and for the war effort. Six years after its initial introduction, General Motors' Electro-Motive Division (EMD) FT locomotive was still that company's principal offering. With the war coming to an end, EMD was frantically gearing up to meet the pent-up post-war demand that would have to be filled. UP was not alone in seeking the ideal 6,000 horsepower locomotive. The builders and the other railroads also saw this figure as the best solution to many operational needs. In February 1945, EMD first offered its E7 passenger locomotive in 6,000 horsepower A-B-B sets. The company's post-war freight offering, first built in July 1945, was the F3 locomotive, in A-B-B-A sets that also added up to the needed 6,000 horsepower.

Other builders were also working on their own designs. American Locomotive (Alco), which had been the source for UP's most recent modern steam locomotives, first offered its 6,000 horsepower locomotives for freight service in January 1946, in the form of it's A-B-B-A 1,500 horsepower freight units, later known as its FA and FB models. For passenger units, the first Alco postwar passenger units, the six-axle 2,000-horsepower PA/PB design, were first produced in June 1946, usually in three unit A-B-A sets.

But this later variety was a year after UP first went looking for locomotives to dieselize the South-Central District. At the time UP began its search, in early 1945, only Baldwin had a existing design that met UP's specifications, in the form of a demonstrator six-axle, 2,000 horsepower passenger unit in two units completed in January and March 1945. In response to UP's request, Baldwin offered to build a much larger design based in the recent demonstrators: a 6,000 horsepower, two-unit locomotive that today's locomotive fans know as Baldwin's unique Centipede locomotives, named for the "all-wheels" appearance of the 12 axle 2-D+D-2 wheel arrangement (the same as Big Boy's 4-8-8-4 wheel arrangement). Although EMD's passenger E7 was just becoming available, UP saw that model as a passenger unit and was looking for a beefier design, with heavier traction motors and a more substantial diesel engine.

In addition to the Baldwin design, UP also found what it was looking for in the opposed piston diesel engine that Fairbanks-Morse had so successfully furnished to the U. S. Navy during the war. The combination of F-M's opposed piston submarine engine, and the heavy GE traction motors (that would later be used in the huge all-electric locomotives for Great Northern and Virginian) was just what UP wanted.

After some back and forth correspondence between Omaha and New York during mid 1945 about the need to get moving on the dieselization question, an order was placed for the three F-M units in August 1945, and a similar order was placed for the two Baldwin units in October. Each "Authority For Expenditure" stated that the locomotives were to be operated between Salt Lake City and Los Angeles, and that each was to have 6,000 horsepower and a cost of $600,000. The F-M locomotives were delivered in December, but there were delays in the Baldwin order that stretched the delivery date into mid 1946, then into mid 1947. With this latest delay, and after a visit to the Baldwin plant showed that the builder had yet to begin buying parts to get the units into production, UP lost patience and canceled the Baldwin order in April 1947.

Railway Age, October 13, 1945, wrote: "The Union Pacific will receive from Fairbanks, Morse & Co., on November 1 a three-unit, 6,000-hp. Diesel-electric locomotive, which has been designed for a maximum operation of 65 m.p.h. This locomotive will be tested on a run from south of Salt Lake City, Utah, to Los Angeles, Cal., in freight hauling and possibly in passenger service. The Union Pacific will also receive a four-unit, 6,000-hp. Diesel-electric locomotive from the ElectroMotive division of the General Motors Corporation, which is to be tested between Green River, Wyo., and Ogden, Utah, under exact loads and conditions to determine comparison of performance of this unit with the Union Pacific's "Big Boys," or 4000 class, 4-8-8-4 type, locomotives. Later tests of the new locomotive will also be conducted between Salt Lake City and Los Angeles." (Railway Age, October 13, 1945, page 622)

The Erie-Builts Are Delivered

With its delivery in December 1945, this first road locomotive for UP was given the unusual road number of 50-M, with the three units being identified as 50-M-1A, 50-M-2A, and 50-M-3B. The three units were initially leased to UP as a demonstration. Current research suggests that this M-series numbering was a hold-over from the early years of UP's McKeen motor cars, and was used to denote "Motor." The number 50-M was in series with UP's Streamliner numbering scheme of 1-M and 2-M for the City of San Francisco and City of Los Angeles E2 trainsets bought in 1937, 3-M, 4-M, and 6-M for the three City of Denver trainsets, 5-M for the A-B E3 locomotive bought in 1939, and 7-M, 8-M, and 9-M for the three A-A sets of E6s, bought in 1940. Although the City of San Francisco, City of Los Angeles, and City of Denver locomotives never actually carried these M-series numbers, the quantities do match. The planned road numbers for the E7s delivered in 1946 were in this same M-series numbers, as 10-M for two of the six cab units. Three of the seven E7Bs were to receive continuations of the 7-M, 8-M and 9-M locomotive sets.

Because F-M did not have the production capacity at its Beloit, Wisconsin, plant, what were originally to be UP's first road freight locomotives, were built by General Electric under contract for F-M at GE's Erie, Pa., factory, hence the "Erie-built" nickname. UP's inital three units were the first of the model to be completed, but a strike at the F-M plant in Beloit delayed further production for additional locomotives for almost a full year. In the meantime, the three initial units tested extensively in both freight service and passenger service on the South-Central District. The units were found to be geared too high for freight service, and too low for passenger service. After the units were regeared for 104 mph passenger service, they were formally purchased by UP in May 1946.

The planned delivery of additional Erie-built units in mid 1946 meant that UP would soon run out of numbers in its fleet of passenger units. While the E7s from EMD were originally to be delivered in the M-series numbering scheme, they were instead delivered in the new 900-series scheme. The need for a new numbering scheme to replace the M-series for the road's diesel locomotives was becoming apparent from the increased quantities of diesels and from its confusing and cumbersome nature. The number series selected for the road's diesel locomotives was the 900-series, in sequence with the road's 800-series passenger 4-8-4 steam locomotives. This series may have been selected because so many of the diesels were also passenger locomotives. Although the E7s were the first new units to receive the new numbering scheme when they were delivered in May 1946, the first in-service units seen in the new scheme were the three F-M Erie-built units. These three units were renumbered from their original 50-M numbers to their new 900-series numbers of 981A, 982A, and 983B, in May 1946 at the time of UP's formal purchase of the more Erie-built units from F-M a year later, following settlement of the strike at F-M's beloit plant.

After testing the Erie-built units, UP found that the two- or three-unit concept of a 6,000 horsepower locomotive for freight service wasn't quite ready. With the change in the railroad's presidency in January 1946, the new president, George Ashby, saw greater value in the multiple unit concept that the builders were marketing with the F3 from EMD and the FA/FB from Alco. On October 2, he wrote to the Board of Directors, "As per discussions with you from time to time, I have been slow to suggest conversion to diesel power but am now convinced we should make a substantial start in that direction. Union Pacific participated in no small part in the development of the diesel locomotive about ten years ago and has not yet accepted it." In December 1946, he placed a combined $22 million order with EMD and Alco for 162 units that would be used to fully dieselize the South-Central District, but additional F-M Erie-built units were noticeably not part of the order.

However, in 1947-48, to fill out its needs for more secondary passenger motive power, UP did buy an additional ten Erie-built units, including six additional cab units and four additional booster units. As they were delivered, all thirteen-units of UP's Erie-builts were used on the South-Central District. In many cases, due to their similar electrical systems, the Erie-built units were used in consists with the Alco PA/PB units.

UP 984A and 985A were completed in June 1947, and were displayed during the last week of June at the American Association of Railroads convention in Atlantic City, New Jersey. Following display at Atlantic City, the two units were reconditioned by F-M, assembled into a 6,000 horsepower set with the addition of a booster unit, and delivered to UP in November 1947.

While in passenger service, some Erie-built units were used on the Kansas Division, where they ran in A-B-A configuration on Trains 9 and 10 (the City of St. Louis) and Trains 69 and 70 (the local). A single set would come in from the West on the COSL, terminate in Kansas City, then go back west to Salina on 69; back to KC on 70, and then leave the division on the westbound COSL in the evening. In Kansas, the Erie Builts were often paired with Alco PAs. (Jeff Aley, email to UP Modelers Yahoo discussion group, October 1, 2004)

The FM Erie-built units were also used on Trains 37 and 38 "Pony Express" on the Kansas Division (Topeka to be specific) while they were still in the 700-series numbers. In July 1956, they were the power used on a the Portland-Seattle pool train on July 5, 1956, and they were in the 650-series numbers. (Art Gibson, email to UP Modelers Yahoo discussion group, October 2, 2004)

Erie-Builts Moved To NWD

With the deliveries of new E8s for passenger service in 1953, the F-M units were reassigned to the Northwestern District, where they remained in secondary passenger service until their retirement in 1960-61.

Throughout their time on UP, the older Erie-builts carried four different number series. As already mentioned, the first three units were changed from freight service to passenger service in May 1946 and renumbered from their original 50-M series numbers to the new 900-series numbers, with an A-suffix for the cab units and a B-suffix for the booster units.

Less than two years later, in the general renumbering of all of UP's passenger locomotives in early 1948, after UP had received two more Erie-built cab units and two more Erie-built booster units, the F-M Erie-builts were renumbered to the 700 series. This new 700 series numbers followed the 600 series for the Alco PA/PB passenger units, and preceded the EMD units in the low-900 series.

The last four cab units and two booster units were delivered in the 700-series numbers. In this new number scheme, only the booster units were given a B-suffix (some booster units from other builders received a C-suffix), while the cab units received no letter suffix at all.

Reassigned from passenger service (700 series) to freight service (650 series) in February 1953; reballasted from 341,500 pounds operating weight (238,400 pounds weight on drivers) to 357,300 pounds operating weight (248,900 pounds weight on drivers); gear ratio changed from 63:24 to 68:19.

With their reassignment to the Northwestern District in 1953, and to clear the 700-series for use by new GP7s, the Erie-builts were renumbered to the 650-series numbers, which they kept until their retirement.


Several sources have stated that the units were used in passenger service until 1953 when sufficient EMD E8s arrived to take over most, if not all, passenger trains. Railroad records also state that the Erie-builts (and the Alco PA/PB units) were then converted to freight service. But no photos have surfaced that show the F-M units in freight service, and there are numerous photos that show them in continued passenger service throughout the 1950s, right up to their retirement in 1960 and 1961.

Model Designation

Research has not yet found a formal model designation for these units, other than "2,000 HP Passenger."

The model designation has previously been published in error as being Fairbanks-Morse model ALT-100-3. Research has found that this was merely the form number of the original advertising literature, "ALT" being an abbreviation of Advertising Literature Technical. Early researchers assumed the designation was a specification number for the locomotive.

Exterior Appearance

The time span of production of all for all F-M's Erie-built units was from the initial three for UP in late 1945, through to the last Erie-built, completed for New York Central in April 1949. During that three and a half year period, F-M built a total of 111 units (82 cab units and 29 booster units). During that time period, F-M made changes in some of the exterior details on the units as they were delivered.

UP's 13 F-M Erie-built units were built throughout the time span of Erie-built production, so UP's units do differ slightly in carbody appearance. According to noted locomotive historian David Thompson, these different carbody features include the stepped or smooth roof above the cab, the recessed handrail areas at the left and right rear corners, style of ladder below the center door, and the style of grille coverings along the top. UP's first two cab units had the stepped cab roof, recessed handrails, horizontal grilles, and stirrup ladders that angled outward below their center doors. The first booster unit shared these same features, except the stepped cab roof. All of the other six cab and four booster units had the smooth cab roof, screens instead of horizontal grilles, straight stirrup ladders instead of ladders that angled outward below the center door, and did not have recessed handrail areas at the rear corners.

While in service in Southern California, UP's Erie-built units were equipped with large rooftop ventilators, along with large rooftop exhaust screens covering their twin exhaust stacks. The rooftop exhaust screens look like large boxes mounted above the exhaust stacks, and were in fact cinder catchers. They were made of heavy mesh netting and were large to allow them to cover both exhaust stacks. They look like solid boxes because they are black from exhaust. They had a curved top to match the curve of the roof, since a regular rectangular box would have worked just as well. There appears to have been two different styles. One had a single arch, about 12 inches high that tapered to the sides and ends at the roof surface. The other style appears to be still 12 inches high, but the entire arch is 12 inches high, kind of like a 12 inch high box bent to match the contour of the roof. These rooftop exhaust screens were fabricated by Union Pacific.

All of the 13 Erie-built rode on two trucks that each had an unpowered center idler axle, called an A-1-A truck. The first five of UP's Erie-builts (four cab units and one booster unit) were equipped with special truck that was fabricated by GE for use under the F-M Erie-built locomotives. By late 1946, F-M had completed its arrangements with General Steel Castings Co. to furnish a cast-frame truck that resembled a similar truck that GSC was furnishing to Alco for use on its competing PA/PB passenger units. Although F-M first offered this new cast truck design beginning in October 1946, UP's next two cab units were equipped with the fabricated design. The last eight units for UP, delivered in 1947 and 1948 (four cab units and four booster units) were equipped with this General Steel Castings truck. The drop equalizers on these later trucks were shaped differently. The design used by ALCo were flat on top and sloped on the bottom, while F-M's were the opposite, and F-M used a different base for the side springs that extended onto the equalizers (the same as was later used on the C-Liner truck).

David Thompson has described the exterior variations of the F-M Erie-built locomotives:

Phase Ia: the original carbody with square front windshields, step roof over the cab, stainless steel grills, and the raised sections on the nose for the class lights.

UP 50-M-1A,2A,3B would be Phase Ia1 since they had two horizontal grabs in the rear side corner recess instead of vertical handrails in the recess.

Phase Ib: the stainless grills were eliminated and the middle stirrup step was eliminated in favor of steps in the fuel tank.

Phase IIa: the curved windshields, smooth cab roof, smooth nose for the class lights, and a straight middle stirrup step appeared. The recesses at the back side corner were filled in but the handrails were still recessed. (I haven't been able to confirm this, but C&NW 5001A may have had the full recess. C&NW's other three Eries had the filled recess, though.)

Phase IIb: the recesses disappear completely.

(Read more about the carbody phases on the FM Erie-built locomotives; includes a full roster of all Erie-built locomotives)

(NOTE: In the article published in "The Streamliner", on page 12, column 3, credit for the carbody phases on the Erie-built locomotives was wrongly given to David Sweetland. It is actually David Thompson who developed and refined the carbody phases, and who graciously helped the author with this article.)

Road Number Listing

Fairbanks-Morse Erie-built A-units (8 units)

Dec 1945
Date To
981 Series
Date To
700 Series
Date To
650 Series

50-M-1A 981A Aug 1946 700 Mar 1948 650 Feb 1953 Dec 1945 L1060 27789 Aug 1961
50-M-2A 982A Aug 1946 701 Mar 1948 651 Feb 1953 Dec 1945 L1061 27790 May 1961
  984A (new) 702 Mar 1948 652 Mar 1953 Nov 1947 L1117 29391 Mar 1961
  985A (new) 703 Mar 1948 653 Feb 1953 Nov 1947 L1118 29392 Jul 1961
      704 (new) 654 Feb 1953 Mar 1948 L1136 29405 Jul 1960
      705 (new) 655 Feb 1953 Mar 1948 L1137 29406 Jul 1961
      706 (new) 656 Feb 1953 Apr 1948 L1138 29407 Mar 1961
      707 (new) 657 Feb 1953 Apr 1948 L1139 29408 Aug 1961

Fairbanks-Morse Erie-built B-units (5 units)

Dec 1945
Date To
983B Series
Date To
700B Series
Date To
650B Series


50-M-3B 983B Aug 1946 700B Mar 1948 650B Feb 1953 Dec 1945 L1062 27791 Jul 1961
  986B (new) 702B Mar 1948 652B Feb 1953 Nov 1947 L1127 29431 Mar 1961
  987B (new) 703B Mar 1948 653B Feb 1953 Nov 1947 L1128 29392 Aug 1961
      704B (new) 654B Feb 1953 Mar 1948 L1142 29436 May 1961
      706B (new) 656B Feb 1953 Apr 1948 L1143 29437 Oct 1960

F-M Order Numbers

The 13 Fairbanks-Morse Erie-built units on UP, (8 cab units and 5 booster units) were delivered in three separate orders.

F-M Order
Date UP Road Numbers
LD-6 Dec 1945 UP 50-M series; later UP 981A, 982A and 983B; then UP 700, 701, 700B, then UP 650, 651, 650B
LD-28 Nov 1947 UP 984A, 985A, 986B, 987B; later UP 702, 703, 703B; then UP 654, 655, 653B
LD-34 Mar-Apr 1948 UP 704-707, 704B, 706B; then UP 654-657, 654B, 656B

Additional Reading

Aldag, Robert, Jr. "How Fairbanks-Morse got into the locomotive business, Part 1" Trains, Volume 47, Number 5, March 1987, pp. 24-36

Dover, Dan, and Dick Will. "Fairbanks-Morse Builder Record" Extra 2200 South, Volume 8, Number 7, August-September 1970, pp. 23-27

Kirkland, John F. The Diesel Builders, Fairbanks-Morse and Lima-Hamilton. (Interurban Press, 1985)

Smith, J.C., Jr. "FM's Erie-builts" Railroad Model Craftsman, Volume 44, Number 5, October 1975, pp. 60-67

Stagner, Lloyd E. Union Pacific Motive Power in Transition 1936-1960 (South Platte Press, 1993)

Strack, Don. Diesels of the Union Pacific, 1934-1982, The Classic Era, Volume I. (Withers Publishing Co., 1999)

Sweetland, David R. Erie-builts and H20-44s. (Withers Publishing Co., 1999)


UP 653 at ABPR Railfan.net

UP 655 at ABPR Railfan.net