The Union Pacific 4014 'Big Boy' is the largest steam locomotive in operation in the world today. It delivers 7,500 horsepower at drawbar, and 8,300 HP at cylinder. It can travel at the top speed of 80 mph (130 km/h) on standard gauge railway track (1.435 m). It runs as a chartered train for the Union Pacific steam program, hauling freight cars.
The 4014 'Big Boy' is a class 4884-1 class locomotive, with four-wheel leading truck, two sets of eight driving wheels, and four-wheel trailing truck (4884 Whyte notation). This wheel configuration has been used only by the Union Pacific 'Big Boy' steam locomotives, which had been built between 1941 and 1944 by the American Locomotive Company (ALCO).
Specifications
Type: steam locomotive
Weight: 386.12 tons
Length: 26.11 m (85 feet, 8 inches)
Width: 3.35 m (11 feet)
Fuel: coal (originally); today fuel oil.
Firebox Volume: 14 m3 (150 square feet)
Boiler Pressure: 2.1 MPa
Cylinders: 4
Valve Type: piston valves
Brake: pneumatic.
Below, photo of UP 4014 steam locomotive in 1948.
The 4014 Big Boy steam locomotive (video)
