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The Union Pacific FEF Series includes three 4-8-4 steam locomotive types built by the American Locomotive Company between 1937 and 1944 and operated by the Union Pacific Railroad until 1959.

Union Pacific FEF Series
Union Pacific 844, Painted Rocks, NV, 2009 (crop).jpg
Union Pacific 844 running through Painted Rocks, Nevada, on September 15, 2009
Type and origin
Power typeSteam
BuilderAmerican Locomotive Company
Build date1937–1944
Total produced45
 • Whyte4-8-4
 • UIC2′D2′ h2
Gauge4 ft 8 12 in (1,435 mm)
Driver dia.FEF-1: 77 in (1,956 mm),
FEF-2/3: 80 in (2,032 mm)
WheelbaseLoco & tender: 98 ft 5 in (30.00 m)
Adhesive weightFEF-1: 270,000 lb (122.5 tonnes),
FEF-2: 265,520 lb (120.4 tonnes),
FEF-3:270,300 lb (122.6 tonnes)
Loco weightFEF-1: 465,000 lb (210.9 tonnes),
FEF-2: 478,640 lb (217.1 tonnes),
FEF-3: 490,700 lb (222.6 tonnes)
Total weightFEF-1: 830,150 lb (376.5 tonnes),
FEF-2: 894,960 lb (405.9 tonnes),
FEF-3: 912,250 lb (413.8 tonnes)
Fuel typeCoal from 1937 to 1946
No. 5 fuel oil from 1946 onwards
Fuel capacityCoal: 50,000 lb (22.7 tonnes),
Oil: 6,000 US gal (22,712.5 litres; 4,996.0 imperial gallons)
Water cap20,000 US gal (76,000 l; 17,000 imp gal)
 • Firegrate area
100 sq ft (9.3 m2)
Boiler86 ​316 in (2189.2 mm) diameter
Boiler pressure300 lbf/in2 (2.07 MPa)
Heating surface4,224 sq ft (392.4 m2)
 • Tubes2,204 sq ft (204.8 m2)
 • Flues1,578 sq ft (146.6 m2)
 • Firebox442 sq ft (41.1 m2)
 • TypeFEF-1/3: Type A
FEF-2: Type E
 • Heating area1,400 sq ft (130 m2)
Cylinder sizeFEF-1: 24.5 in × 32 in (622 mm × 813 mm),
FEF-2/3: 25 in × 32 in (635 mm × 813 mm)
Performance figures
Tractive effortFEF-1: 63,611 lbf (283.0 kN),
FEF-2/3: 63,750 lbf (283.6 kN)
Factor of adh.FEF-1/3: 4.24
FEF-2: 4.17
OperatorsUnion Pacific Railroad
ClassFEF-1, FEF-2, and FEF-3
NumbersFEF-1: 800–819,
FEF-2: 820–834,
FEF-3: 835–844
DeliveredFEF-1: 1937,
FEF-2: 1939,
FEF-3: 1944
DispositionFEF-1: 814 preserved, remainder scrapped,
FEF-2: 833 preserved, remainder scrapped,
FEF-3: 844 in excursion service, 838 in storage as source of spare parts, remainder scrapped

The 45 locomotives were the last steam locomotives built for the Union Pacific. They represented the epitome of dual-service steam locomotive development; funds and research were being concentrated into the development of diesel-electric locomotives. Designed to burn coal, they were converted to run on fuel oil in 1946.[1] They pulled a variety of passenger trains, such as the Overland Limited, Los Angeles Limited, Portland Rose and Challenger[2], until diesel-electric locomotives took over passenger service. Many FEF Series locomotives were later reassigned to freight service during the last few years of their careers.

The term "FEF" was an acronym for "four-eight-four," the Whyte notation of the locomotives. This means that the locomotives had four leading wheels on two axles, eight powered and coupled driving wheels on four axles and four trailing wheels on two axles.

Four FEF Series locomotives survive today, including No. 844, which remains in operational condition and now runs in excursion service. Today, the 844 is one of the Union Pacific's oldest serving locomotives[3] and the only steam locomotive never retired by a North American Class I railroad.[4]



During the late 1930s, the rising trainloads started to exceed the limits of the 4-8-2 that were the mainstay of the UP passenger operations. One day, in 1937, with UP President William Jeffer's business car in the rear, a "7000" Class 4-8-2 demonstrated the lack of steaming power inherent in the type. Even when the train was waiting for rescue, a telegram was sent to ALCO in Schenectady seeking something better. The result was a superb class of 45 locomotives that could run at 120 mph and produce between 4,000 and 5,000 drawbar horsepower.


The FEF Series consisted of three classes of steam locomotives: FEF-1, FEF-2, and FEF-3.

Table of orders and numbers
Class Quantity Manufacturer Serial Nos. Year built UP No. Notes
FEF-1 20 American Locomotive Company 68808-68827 1937 800–819 Converted to oil fuel in 1945-1946. No. 814 on display in Council Bluffs.
FEF-2 15 American Locomotive Company 69161-69175 1939 820–834 Converted to oil fuel in 1945-1946. No. 833 on display in Ogden.
FEF-3 10 American Locomotive Company 72782-72791 1944 835–844 Converted to oil fuel in 1945-1946. No. 844 in excursion service since 1960; renumbered to 8444 from 1962 to 1989. No. 838 stored in Cheyenne.


FEF-1 814 on static display at the RailsWest Railroad Museum in Council Bluffs, Iowa.

The first twenty locomotives, numbered 800–819, were delivered by ALCO in 1937. The "800"s as a whole followed – like Northumbrian 108 years earlier – the simplest possible arrangement of only having two outside cylinders. Fitting ALCO's lateral motion devices to the leading coupled wheels eased the negotiation of curves. Complicated accessories often spoiled the basic simplicity of so many US locomotives, but UP resisted most of them, resulting in an elegant, uncluttered appearance. Despite frequently moving at speeds over 100 mph (161 km/h), the forces and stresses on the coupling and connecting rods were kept within acceptable limits. There were thus excellent results, and there were many reports of the class reaching the design limit of 110 mph (177 km/h).


FEF-2 825 in 1943.

The second batch of fifteen was delivered in 1939. These had several improvements, including larger cylinders, better tractive effort, taller driving wheels, and smoke deflectors on the sides of the smokebox. The greatest change, however, was the provision of a fourteen wheeled “pedestal” or “centipede” tender, in place of the twelve wheeled ones of the first twenty locomotives. Thus, the first locomotives became known as "FEF-1," while these were known as "FEF-2."


Union Pacific FEF-3 844 near Kosse, Texas.

Except for the use of some substitute materials, the final batch of ten were nearly identical to the FEF-2. After World War II, coal supplies were affected by a series of strikes. In order to safeguard operations, UP converted the 800s to oil burning, and a 6,000 US gallons (23,000 l; 5,000 imp gal) tank was fitted in the bunker space. Otherwise, few modifications were needed to ensure years of mainline service. These were the last steam locomotives delivered for the UP, and they provided excellent results for crews. On one occasion, one of the engines of the FEF-3 class pulled a 1,000-ton passenger train at 100 mph. Like many of the "late era" steam locomotives, their final design was cut short by the advent of diesel locomotives, the new monarchs of the rails. A former manager of the Union Pacific Steam Program once commented on the FEF series, saying that "although it is stated that the UP FEF Series were designed to safely operate at 120 mph (190 km/h), no one really knows how fast the final 4-8-4 could go."

Surviving examplesEdit

Four FEF Series locomotives survive. Three locomotives (one from each class) are preserved, of which only one is operational. The fourth locomotive (an FEF-3) is stored out of public view.

Type Number Owner Location Current Status Notes
FEF-1 814 RailsWest Railroad Museum Council Bluffs, Iowa Static Display
FEF-2 833 Utah State Railroad Museum Union Station, Ogden, Utah Static Display Was Originally on Display at Pioneer Park in Salt City, Utah
FEF-3 838 Union Pacific Railroad Union Pacific Steam Shop, Cheyenne, Wyoming Stored Source of spare parts for 844.
FEF-3 844 Union Pacific Railroad Union Pacific Steam Shop, Cheyenne, Wyoming Operational The only steam locomotive never retired by a North American Class I railroad.[5]

See alsoEdit


  1. ^ "Union Pacific 4-8-4 "Northern" Locomotives in the USA". Retrieved 2019-06-05.
  2. ^ See Edmonson, Harold A. and Goodheart, David. "Union Pacific's 8444," at 1 (1989, Goodheart Publications).
  3. ^ Klein, Maury (2011). Union Pacific: The Reconfiguration: America's Greatest Railroad from 1969 to the Present. New York: Oxford University Press. p. 163.
  4. ^ Union Pacific Railroad (2012). "Living Legend No. 844". Retrieved February 16, 2014.
  5. ^ UP historical locomotives Archived September 6, 2011, at the Wayback Machine

Further readingEdit

  • Bush, John E. (2013). Building Union Pacific 844: The Birth of the FEF-3 Steam Class (1st ed.). South Platte Press. ISBN 978-0-942035-98-8.
  • Kratville, William W. (1967). The Mighty 800 (1st ed.). Kratville Publications. ASIN B0007EME4Y.