Union Pacific 4006

Union Pacific 4006

300px Big Boy 4006 on display at the Museum of Transportation, outside of St. Louis, Missouri

Type and origin Power type Steam Builder American Locomotive Company Build date 1941

Specifications Configuration 4-8-8-4 UIC class (2′D)D2′ h4 Gauge 4 ft 8 1⁄2 in (1,435 mm) standard gauge Leading dia 36 in (914 mm) Driver diameter 68 in (1,727 mm) Trailing dia 42 in (1,067 mm) Wheelbase 72 ft 5.5 in (22.09 m) Length Locomotive: 85 ft 3.4 in (25.99 m) Overall: Width 11 ft (3.4 m) Height Adhesive weight Loco weight Tender weight (2/3 load) Loco & tender weight Fuel type Coal Fuel capacity 28 short tons (25.4 t; 25.0 long tons) Water cap 25,000 US gal (95,000 L; 21,000 imp gal) Boiler 95 in (2,400 mm) Boiler pressure 300 lbf/in2 (2.1 MPa) Firegrate area 150 sq ft (14 m2) Heating surface 5,735 sq ft (533 m2)  • Tubes and flues 5,035 sq ft (468 m2)  • Firebox 720 sq ft (67 m2) Superheater Type A  • Heating area 2,043 sq ft (190 m2) Cylinders 4 Cylinder size 23.75 in × 32 in (603 mm × 813 mm)

Performance figures Maximum speed 80 mph (130 km/h) Power output 6,290 hp (4,690 kW) Tractive effort 135,375 lbf (602.18 kN) Factor of adh 3.99

Career Operators Union Pacific Railroad Class 4884-1 Disposition Display

Cost to build USD$265,000

Union Pacific 4006, one of the largest steam locomotives ever built, is a 4-8-8-4 Big Boy locomotive that was built in 1941 and retired in 1961 and is one of eight surviving Big Boys. This Big Boy also has the most mileage of all the Big Boys during its service years, traveling 1,064,625 miles.

This locomotive is on display at the Museum of Transportation in St. Louis, Missouri.