Union Pacific FEF series

Union Pacific FEF series
Union Pacific FEF-2 No. 830 pulls a "Fast Mail" train in November 1954
Type and origin Power type Steam Builder American Locomotive Company (ALCO) Build date 1937–1944 Total produced 45
Specifications Configuration: ​  • Whyte 4-8-4  • UIC 2′D2′ h2s Gauge 4 ft 8+1⁄2 in (1,435 mm) Driver dia. FEF-1: 77 in (1,956 mm), FEF-2/3: 80 in (2,032 mm) Wheelbase Loco & tender: 98 ft 5 in (30.00 m) Length Loco & tender: 114 ft 2+5⁄8 in (34.81 m) Adhesive weight FEF-1: 270,000 lb (122.5 tonnes), FEF-2: 265,520 lb (120.4 tonnes), FEF-3: 270,300 lb (122.6 tonnes) Loco weight FEF-1: 465,000 lb (210.9 tonnes), FEF-2: 478,640 lb (217.1 tonnes), FEF-3: 486,340 lb (220.6 tonnes) Total weight FEF-1: 830,150 lb (376.5 tonnes), FEF-2: 894,960 lb (405.9 tonnes), FEF-3: 907,890 lb (411.8 tonnes) Fuel type Coal from 1937 to 1946 No. 5 fuel oil from 1946 onwards Fuel capacity Coal: 50,000 lb (22.7 tonnes), Oil: 6,000 US gal (22,712.5 litres; 4,996.0 imperial gallons) Water cap. 20,000 US gal (76,000 L; 17,000 imp gal) Firebox: ​  • Grate area 100 sq ft (9.3 m2) Boiler 86 3⁄16 in (2189.2 mm) diameter 100 in (2,540 mm) (OD) Boiler pressure 300 lbf/in2 (2.07 MPa) Heating surface: ​  • Firebox 442 sq ft (41.1 m2)  • Tubes 2,204 sq ft (204.8 m2)  • Flues 1,578 sq ft (146.6 m2)  • Total surface 4,224 sq ft (392.4 m2) Superheater: ​  • Type FEF-1/3: Type A FEF-2: Type E  • Heating area 1,400 sq ft (130 m2) Cylinders Two Cylinder size FEF-1: 24.5 in × 32 in (622 mm × 813 mm), FEF-2/3: 25 in × 32 in (635 mm × 813 mm) Valve gear Walschaerts
Performance figures Tractive effort FEF-1: 63,611 lbf (283.0 kN), FEF-2/3: 63,800 lbf (283.8 kN) Factor of adh. FEF-1/3: 4.24 FEF-2: 4.17
Career Operators Union Pacific Railroad Class FEF-1, FEF-2, and FEF-3 Numbers FEF-1: 800–819, FEF-2: 820–834, FEF-3: 835–844 Delivered FEF-1: 1937, FEF-2: 1939, FEF-3: 1944 Retired 1958-1959 (but 844 never retired) Preserved FEF-1: No. 814 preserved, remainder scrapped FEF-2: No. 833 preserved, remainder scrapped FEF-3: Nos. 844 and 838 preserved, remainder scrapped Disposition FEF-1: No. 814 on display FEF-2: No. 833 on display FEF-3: No. 844 operational in excursion service, No. 838 in storage as source of spare parts

The Union Pacific FEF series consists of 45 4-8-4 "Northern" steam locomotives built by the American Locomotive Company (ALCO) between 1937 and 1944 and operated by the Union Pacific Railroad until 1959. Like other Union Pacific steam classes, the acronym comes from the first letter of the spelling of its wheel arrangement: Four Eight Four.

The final steam locomotives built for the Union Pacific, the FEFs represented the apex of dual-service steam locomotive development in the United States, as funds and research were thereafter 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 reassigned to freight service during the last years of their careers.

Four FEF series locomotives survive, including No. 844, which remains in operational condition and runs in excursion service. 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]