Allegheny 2-8-8-2 vs. Union Pacific Big Boy

Attribute	Allegheny 2-8-8-2	Union Pacific Big Boy
Builder	Alco, Lima Locomotive Works	American Locomotive Company (ALCO)
Wheel arrangement	2-8-8-2	4-8-8-4
Year built	1941-1948	1941-1944
Top speed	50-60 mph	80 mph
Weight	600,000-700,000 lbs	1,200,000 lbs
Length	125 ft	132 ft

History

The Allegheny 2-8-8-2 and Union Pacific Big Boy are two of the most iconic steam locomotives in American history. The Allegheny was built by the Lima Locomotive Works for the Chesapeake and Ohio Railway in the 1940s, while the Big Boy was built by the American Locomotive Company for the Union Pacific Railroad in the 1940s as well. Both locomotives were designed to haul heavy freight trains over mountainous terrain, and they were among the largest steam locomotives ever built.

Design

The Allegheny 2-8-8-2 and Union Pacific Big Boy both featured a articulated wheel arrangement, which allowed them to navigate sharp curves and uneven track more easily. The Allegheny had a wheel arrangement of 2-8-8-2, meaning it had two leading wheels, two sets of eight driving wheels, and two trailing wheels. The Big Boy, on the other hand, had a wheel arrangement of 4-8-8-4, with four leading wheels, two sets of eight driving wheels, and four trailing wheels. This difference in wheel arrangement gave the Big Boy a slight advantage in terms of stability and traction.

Size

One of the most striking differences between the Allegheny 2-8-8-2 and Union Pacific Big Boy is their size. The Big Boy was significantly larger and heavier than the Allegheny, with a length of over 132 feet and a weight of over 1.2 million pounds. In contrast, the Allegheny was "only" around 125 feet long and weighed around 778,000 pounds. This difference in size meant that the Big Boy could haul heavier trains and operate more efficiently on long, straight stretches of track.

Performance

Both the Allegheny 2-8-8-2 and Union Pacific Big Boy were known for their impressive performance on the rails. The Allegheny was capable of producing around 7,500 horsepower, while the Big Boy could produce over 6,000 horsepower. This difference in horsepower meant that the Allegheny was slightly more powerful and could accelerate more quickly than the Big Boy. However, the Big Boy's larger size and weight gave it an advantage when it came to hauling heavy freight trains up steep grades.

Legacy

Despite their differences, both the Allegheny 2-8-8-2 and Union Pacific Big Boy have left a lasting legacy in the world of steam locomotives. The Allegheny was retired from service in the 1950s, while the Big Boy continued to operate until the late 1950s. Today, both locomotives can be found in museums and are popular attractions for train enthusiasts. The Big Boy, in particular, has been restored to operating condition and has been used in special excursions and events.