4-8-2 "Mountain" Steam Locomotives in the USA

Class 4-8-2 A Light Mountain (Locobase 231)

Data from tables in 1930 Locomotive Cyclopedia, "Two More Standard Locomotives," Railway Mechanical Engineer, Volume 93, No 1 (January 1919), pp. 25-30, and from American Locomotive Company, Standardized Locomotives, US Railroad Administration (Alco Pamphlet 10049, 1918), pp. 28-29, reprinted by (Ocean, NJ: Specialty Press , 1973) and DeGolyer, Vol 58, pp. 108+.

See also "Standard Equipment Specialties," Railway Mechanical Engineer, Volume 93, No 3 (March 1919), pp. 137-138 for a list of all the "special equipment" by manufacturers--everything from air brakes to lubricators to rolled steel wheels--and the USRA designs on which they appeared.

Its boiler contained the same tube and flue count as the USRA's Heavy Pacifics and Heavy Mikados (Locobases 173 and 41). Firebox heating surface included 105 sq ft (9.75 sq m) in the combustion chamber and 28 sq ft (2.60 sq m) in arch tubes. Cylinders were served by piston valves measuring 14" (356 mm) in diameter.

Standard light "Mountain" design as conceived for mass production during World War I. Four railroads bought 47 locomotives, 25 going to the Southern. Baldwin built 15 (for the Southern), Alco-Richmond supplied 15, and Alco-Schenectady delivered 17 to the MoPac and the Southern. Most later Mountains had a higher superheater to evaporative heating surface ratio and a higher boiler pressure.

Class 4-8-2 B Heavy Mountain (Locobase 232)

Data from tables in 1930 Locomotive Cyclopedia and from American Locomotive Company, Standardized Locomotives, US Railroad Administration (Alco Pamphlet 10049, 1918), pp. 30-31, reprinted by (Ocean, NJ: Specialty Press , 1973), and DeGolyer, Vol 57, pp. 121+. See also Robert A LeMassena, "The USRA HEAVY 4-8-2 and its Illustrious Ascendants", Railway & Locomotive Historical Society Newsletter (Vol 23, #2 - Spring 2003).

See also "Standard Equipment Specialties," Railway Mechanical Engineer, Vol 93, No 3 (March 1919), pp. 137-138 for a list of all the "special equipment" by manufacturers--everything from air brakes to lubricators to rolled steel wheels--and the USRA designs on which they appeared.

Boiler had feedwater heater, firebox heating surface area included 115 sq ft (10.7 sq m) and

34 sq ft (3.15 sq m), and piston valve diameter measured 14" (356 mm).

Only 15 "Heavy" mountains entered service under the USRA aegis. Baldwin built two engines for the C&O, Alco-Brooks supplied three more to the C&O as well as 10 more to the N&W. LeMassena argues, however, that this particular design influenced not only 4-8-2 designs, but also encouraged the development of the larger 4-8-4.