USRA Heavy Mikado

Power typeSteam

Power typeSteam

BuilderALCO, Baldwin, Lima

Build date1918–1944

USRA Heavy Mikado
Type and origin Power type Steam Builder ALCO, Baldwin, Lima Build date 1918–1944 Total produced 233 originals, plus 724 copies[1]
Specifications Configuration: ​  • Whyte 2-8-2  • UIC 1′D1′ h2 Driver dia. 63 in (1,600 mm)[2] Wheelbase locomotive: 36 ft 1 in (11.00 m)[2] Fuel type Coal Fuel capacity 14.5 t (14.3 long tons; 16.0 short tons) Firebox: ​  • Grate area 70.8 sq ft (6.58 m2)[2] Boiler pressure 190 psi (1.31 MPa)[2] Superheater: ​  • Heating area 92.25 m2 (993.0 sq ft) Cylinders Two, outside Cylinder size 27 in × 32 in (690 mm × 810 mm)[2] Valve gear Walschaerts[2] Loco brake Westinghouse air brake Train brakes Westinghouse air brake
Performance figures Power output 3,194 hp (2,382 kW) Tractive effort 60,000 lbf (270 kN)[2]
Career Scrapped 1938-1961 Disposition All scrapped

The USRA Heavy Mikado was a USRA standard class of steam locomotive designed under the control of the United States Railroad Administration (USRA), the nationalized railroad system in the United States during World War I. These locomotives were of 2-8-2 wheel arrangement in the Whyte notation, or 1′D1′ in UIC classification. A total of 233 locomotives were built to this plan for the USRA; postwar, it became a de facto standard design, which was built to the total of 957 locomotives including the USRA originals and all subsequent copies.^[2]

Heavy Mikado used the same running gear as the USRA Light Mikado but were built to a higher axle load, larger cylinders and a much larger boiler for more power and steam-generating ability. Many aspects of the PRR L1s class were carried over to the Heavy Mikado, although not that locomotive's distinctive Belpaire firebox.^[1]