Union Pacific 4014

Union Pacific 4014
Union Pacific No. 4014 departs Denver, Colorado, on July 19, 2025
Type and origin
Power typeSteam
DesignerOtto Jabelmann
BuilderAmerican Locomotive Company (Schenectady Works)
Serial number69585
Build dateNovember 1941
Specifications
Configuration:
 • Whyte4-8-8-4
 • UIC(2′D)D2′ h4
Gauge4 ft 8+12 in (1,435 mm) standard gauge
Leading dia.36 in (914 mm)
Driver dia.68 in (1,727 mm)
Trailing dia.42 in (1,067 mm)
Minimum curve288 ft (88 m) radius/ 20°
Wheelbase
  • Locomotive: 72 ft 5+12 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+78 in (40.48 m)
Width11 ft (3.35 m)
Height16 ft 2+12 in (4.94 m)
Axle load68,150 lb (30,912 kg)
Adhesive weight545,200 lb (272.6 short tons)
Loco weight772,250 lb (386.12 short tons)
Tender weight446,000 lb (223 short tons) (3985 tender)
Total weight1,218,500 lb (609.2 short tons) and 1,477,000 lb (738 short tons) (Combine oil and water)
Tender type25-C
Fuel type
Fuel capacity
  • Total: 6,500 US gal (25,000 L)
  • Usable: 6,100 US gal (23,000 L)
Water cap.25,000 US gal (95,000 L)
Sandbox cap.8,000 lb (4 short tons)
Fuel consumption
  • 20–25 US gal (76–95 L) of fuel oil per mile
  • 200 US gal (760 L) of water per mile
Firebox:
 • Grate area150 sq ft (grate removed in 2019)
Boiler:
 • ModelFire Tube
 • Diameter107 in (2,718 mm)
 • Tube plates22 ft (7 m)
Boiler pressure300 lbf/in2 (2.1 MPa)
Feedwater heaterElesco Type T.P. 502 Exhaust Steam Injector
14,000 US gal / hour capacity
Heating surface:
 • Firebox704 sq ft (65 m2)
 • Tubes967 sq ft (90 m2)
 • Flues4,218 sq ft (392 m2)
 • Tubes and flues5,185 sq ft (482 m2)
 • Total surface5,889 sq ft (547 m2)
Superheater:
 • TypeType E
 • Heating area2,466 sq ft (229 m2)
CylindersFour, outside
Cylinder size24 in × 32 in (610 mm × 813 mm)
Valve gearWalschaerts
Valve typePiston valves
Valve travel7 in (178 mm)
Valve lap1+38 in (35 mm)
Valve lead14 in (6 mm)
Train heatingSteam heat
Loco brakePneumatic, Schedule 8-ET
Train brakesPneumatic
Safety systemsCab signals, PTC
Performance figures
Maximum speed
  • 40–60 mph (64–97 km/h) in regular service
  • 80 mph (130 km/h) (maximum design)
Power output
  • 8,157 hp (6,083 kW) @ Cylinder
  • 6,290–7,000 hp (4,690–5,220 kW) @ Drawbar
Tractive effort138,240 lbf (614.9 kN)
Factor of adh.4.00
Career
OperatorsUnion Pacific Railroad
Class4884-1
Number in class15
Numbers
  • UP 4014
NicknamesBig Boy
LocaleWestern United States
DeliveredDecember 1941
First runDecember 1941
Last runJuly 21, 1959
RetiredDecember 7, 1961
RestoredMay 1, 2019
Current ownerUnion Pacific
(Union Pacific Heritage Fleet)
DispositionOperational
References:

Union Pacific 4014 is a preserved 4884-1 class 4-8-8-4 "Big Boy" type steam locomotive owned and operated by the Union Pacific as part of its heritage fleet. Built in November 1941 by the American Locomotive Company (ALCO) in Schenectady, New York, it was assigned to haul heavy freight trains in the Wasatch mountain range. The locomotive was retired from revenue service on December 7, 1961, and was donated to the Railway & Locomotive Historical Society; thereafter, it was displayed in Fairplex at the RailGiants Train Museum in Pomona, California.

In 2013, UP re-acquired the locomotive and launched a restoration project at its Steam Shop in Cheyenne, Wyoming. In May 2019, No. 4014 moved under its own power after sitting dormant for almost six decades, becoming the world's largest operational steam locomotive and the only operating Big Boy locomotive of the eight that remain in existence. It now operates in excursion service for the UP steam program. No. 4014 became the first mainline steam locomotive to be equipped with the positive train control system in 2021.