United States Railroad Administration 4-6-2 "Pacific" Locomotives in the USA

Class Heavy (Locobase 173)

Data from tables in 1930 Locomotive Cyclopedia and from American Locomotive Company, Standardized Locomotives, US Railroad Administration (Alco Pamphlet 10049, 1918), pp. 26-27, reprinted by by Specialty Press (Ocean City, 1973) and DeGolyer, Volume 58, pp. 48+. (Many thanks to Chris Hohl for his 22 September 2017 email reporting unlikely boiler pressure values for 177 entries. A Locobase macro caused the error.)

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.

Intended to be the standardized Pacific heavy passenger express locomotive, but only twenty were actually allocated by the USRA. The design shared the tube and flue count with two other USRA variants: Light Mikado (Locobase 40) and Light Mountain (Locobase 231). Firebox heating surface included 72 sq ft (6.7 sq m) in the combustion chamber and 28 sq ft (2.6 sq m) in arch tubes. Cylinders were served by piston valves measuring 14" (356 mm) in diameter.

Erie's were built by Alco-Richmond (10) and Baldwin (10) at the direction of the government-run USRA beginning in 1918.

Class Light (Locobase 172)

Data from tables in 1930 Locomotive Cyclopedia and from American Locomotive Company, Standardized Locomotives, US Railroad Administration (Alco Pamphlet 10049, 1918), pp. 24-25, reprinted by Specialty Press (Ocean City, 1973). See also DeGolyer, Volume 58, pp. 35+ and "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.

This was the "light" Pacific design standardized by the government-run USRA created in World War I and built by Baldwin and Alco. Three railroads actually took delivery of 81 locomotives: Atlantic Coast Lines (28 by Alco-Brooks, 17 by Alco-Richmond), the B&O (20 by Baldwin, 10 by Alco-Richmond), and L&N (6 by Alco-Richmond).

Although described as light, the design in fact had a relatively large grate compared to other engines within its axle-loading range. Firebox heating surface included 46 sq ft (4.27 sq m) in the combustion chamber and 27 sq ft (2.51 sq m) in arch tubes. Cylinders were served by piston valves measuring 14" (356 mm) in diameter.

In the literature describing particular railroads' acquisitions, this design often appears either as the direct-from-USRA variant or a later class based on the USRA Light. And very often sources describe the USRA-inspired 4-6-2 as the best, most reliable Pacifics the railroad would own.