Union Pacific 4012
"Big Boy" 4012 on static display at Steamtown National Historic Site, August 2023
Type and origin
Power typeSteam
BuilderAmerican Locomotive Company
Serial number69583
Build dateNovember 1941
Specifications
Configuration:
​
 • Whyte4-8-8-4
 • UIC(2′D)D2′ h4
Gauge4 ft 8+1⁄2 in (1,435 mm)
Leading dia.36 in (914 mm)
Driver dia.68 inches (170 cm)
Trailing dia.42 in (1,067 mm)
Minimum curve288 ft (88 m) radius/ 20°
Wheelbase
  • Locomotive: 72 ft 5.5 in (22.09 m)
  • Overall: 117 ft 7 in (35.84 m)
Length
  • Locomotive: 85 ft 7.8 in (26.11 m)
  • Overall: 132 ft 9+7⁄8 in (40.48 m)
Width11 ft (3.4 m)
Height16 ft 2+1⁄2 in (4.94 m)
Axle load67,500 lb (30,617 kilograms)
Adhesive weight540,000 lb (244,940 kilograms)
Loco weight762,000 lb (345,637 kilograms)
Tender weight342,200 lb (155,219 kilograms) (2/3 load)
Total weight1,250,000 lb (566,990 kilograms)
Tender type25-C
Fuel typeCoal
Water cap.24,000 US gal (91,000 L; 20,000 imp gal)
Firebox:​
 • Grate area150 sq ft (14 m2)
Boiler95 in (2,400 mm)
Boiler pressure300 lbf/in2 (2.1 MPa)
Heating surface5,889 sq ft (547 m2) ​
 • Tubes and flues5,185 sq ft (482 m2)
 • Firebox704 sq ft (65 m2)
Superheater:
​
 • TypeType E
 • Heating area2,466 sq ft (229 m2)
Cylinders4
Cylinder size23.75 in × 32 in (603 mm × 813 mm)
Performance figures
Maximum speed80 mph (130 km/h)
Power output5,300–7,000 hp (4,000–5,200 kW) @ 41 mph
Tractive effort135,375 lbf (602.18 kN)
Factor of adh.3.99
Career
OperatorsUnion Pacific Railroad
Class4884-1
Numbers4012
First run1941
Last run1959
Retired1962
RestoredMay 5, 2021 (cosmetically)
DispositionOn static display at Steamtown National Historic Site Scranton, PA

Union Pacific 4012 is one of eight preserved Union Pacific Big Boy locomotives. Built in November 1941 by the American Locomotive Company (ALCO) of Schenectady, New York, No. 4012 was retired in 1962 and donated to Steamtown, U.S.A, in Bellows Falls, Vermont, and later moved to Steamtown National Historic Site in Scranton, Pennsylvania, where it remains today.

History

Union Pacific 4012, nicknamed "Big Boy", is a 4-8-8-4 type locomotive built by American Locomotive Company in November 1941. It is among the world's largest steam locomotives. One of 25 built, No. 4012 is one of eight of its type to survive the advent of the diesel era. Referred to as an "articulated" locomotive, because it has more than one set of drivers, Big Boy weighs 1,250,000 pounds (570,000 kg). This locomotive worked for 21 years hauling freight between Cheyenne, Wyoming, and Ogden, Utah, logging over 1,000,000 miles (1,600,000 km) before its retirement in 1962.[1]

Photograph of Union Pacific 4012, "Big Boy" at Steamtown, USA in Bellow Falls, Vermont
Union Pacific 4012 at Steamtown, USA in Bellow Falls, Vermont.

No. 4012 was offered to Steamtown, U.S.A. along with a 4-6-6-4 Challenger and an office car. Steamtown founder F. Nelson Blount, faced with space limitations at Steamtown in 1962, could only accept the 4012.[2] The Big Boy was on display at Bellows Falls, Vermont, until 1984, when Steamtown moved to Scranton, Pennsylvania.[1] Since the Steamtown turntable and roundhouse are too small to accommodate the size and weight of 4012,[1] it has remained outdoors since its arrival at Scranton.[3]

The Steamtown Special History Study recommended that this locomotive remain at Steamtown because it is the only articulated locomotive in the Steamtown U.S.A. collection and suggested that due to its good condition, 4012 could be restored to working order. However, the study also recommended that 4012 remain on static display, because it is doubtful that the "track, switches, culverts, trestles, bridges, wyes, turntables, and other facilities that would have to carry it to bear its great weight".[1]

Beginning on October 2, 2019, No. 4012 was removed from public display to begin a cosmetic restoration, including asbestos removal and repainting.[4][5] The cosmetic restoration was completed on May 5, 2021, and the locomotive was returned to static display for National Train Day.[6]

References

  1. 1 2 3 4 Chappell, Gordon. "Union Pacific No. 4012". Steam Over Scranton: Special History Study, American Steam Locomotives. National Park Service. Retrieved July 30, 2022.
  2. ↑ Boyd, Jim (2011). Steamtown In Color. Morning Sun Books. p. 37. ISBN 978-1582483009.
  3. ↑ "Steamtown's Locomotives and Cars". Steamtown National Historic Site. National Park Service. Retrieved March 13, 2012.
  4. ↑ Scranton, Mailing Address: 150 South Washington Avenue; departments, PA 18503-2018 Phone: 570-340-5200 General park infowith options to select specific; Us, offices or employee extensions Contact. "Steamtown National Historic Site's Union Pacific "Big Boy" No. 4012 Removed From Public Display For Cosmetic Restoration and Painting - Steamtown National Historic Site (U.S. National Park Service)". www.nps.gov. Retrieved 2021-01-10.{{cite web}}: CS1 maint: numeric names: authors list (link)
  5. ↑ "Cosmetic Restoration of UP Big Boy Nears Completion at Steamtown". Railfan & Railroad Magazine. 2020-10-09. Retrieved 2021-01-10.
  6. ↑ "WWII-era 'Big Boy' locomotive restored and returned to Steamtown in Scranton for National Train Day". NEPA Scene. 2021-05-05. Retrieved 2021-05-07.

41°24′30.68″N 75°40′18.09″W / 41.4085222°N 75.6716917°W / 41.4085222; -75.6716917

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