Under the Whyte notation system, a Mallet-type locomotive with four leading wheels on a leading truck, two sets of eight driving wheels, and four trailing wheels on a trailing truck.
In the Whyte notation for the classification of steam locomotives by wheel arrangement, a 4-8-8-4 is a locomotive with a four-wheel leading truck, two sets of eight driving wheels, and a four-wheel trailing truck. 4-8-8-4's are commonly knows as Big Boys. Other equivalent classifications are: UIC classification: 2DD2 French classification: 240+042 Turkish classification: 46+46 Swiss classification: 4/6+4/6 The equivalent UIC classification is refined to D2′ for Mallet locomotives. 4-8-8-4 Big Boys were only produced for the Union Pacific Railroad. But they plan on bringing Union Pacific Big Boy #4014 back on the rails in a few years. The UP Big Boys were an expansion of the 4-6-6-4 "Challenger" type articulated locomotive. Although their wheels were an inch smaller than those of the Challengers, they were still able to sustain high speeds. Adding four driving wheels increased the pulling power of the locomotive and reduced the need for helper locomotives over steep grades. Other American railroads considered buying 4-8-8-4s, including the Western Pacific Railroad, which already rostered large 2-8-8-2s and 4-6-6-4s, but diesel locomotives were gaining popularity and soon were able to displace these monster locomotives.
The numerical value of 4-8-8-4 in Chaldean Numerology is: 0
The numerical value of 4-8-8-4 in Pythagorean Numerology is: 0
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