Milwaukee Road class F7

Milwaukee Road class F7

300px A class F7 being moved out of the Alco factory

Type and origin Power type Steam Builder American Locomotive Company Serial number 69064–69069 Build date August to September 1938 Total produced 6

Specifications Gauge 4 ft 8 1⁄2 in (1,435 mm) standard gauge Leading dia 36 in (914 mm) Driver diameter 84 in (2,134 mm) Trailing dia 38 and 44 in (965 and 1,118 mm) Wheelbase Loco & tender: 89 ft 10 in (27.38 m) Length 100 ft 0 in (30.48 m) Axle load 72,250 lb (32,770 kilograms; 32.77 metric tons) Adhesive weight 216,000 lb (98,000 kilograms; 98 metric tons) Loco weight 415,000 lb (188,000 kilograms; 188 metric tons) Loco & tender weight 791,000 lb (359,000 kilograms; 359 metric tons) full Fuel type Coal Fuel capacity 50,000 lb (23,000 kilograms; 23 metric tons) Water cap Boiler pressure 300 lbf/in2 (2.07 MPa) Firegrate area 96.5 sq ft (8.97 m2) Heating surface 4,166 sq ft (387.0 m2) Superheater Type E  • Heating area 1,695 sq ft (157.5 m2) Cylinders Two, outside Cylinder size

Performance figures Tractive effort 50,294 lbf (223.72 kN) Factor of adh 4.29

Career Operators Milwaukee Road Numbers 100–105 Retired November 1949 to August 1951 Disposition All scrapped.

The Milwaukee Road's class F7 comprised six (#100–#105) high-speed, streamlined 4-6-4 "Baltic" or "Hudson" type steam locomotives built by Alco in 1937–38 to haul the Milwaukee's Hiawatha express passenger trains. Following on from the success of the road's class A 4-4-2s, the F7s allowed the road to haul heavier trains on the popular Chicago–Twin Cities routes.

The F7s are major contenders for the fastest steam locomotives ever built, as they ran at over 100 miles per hour (160 km/h) daily. One run in January 1941 recorded by a reporter for Trains magazine saw 110 miles per hour (180 km/h) achieved twice—in the midst of a heavy snowstorm. Baron Gérard Vuillet, a French railroading expert, once recorded a run between Chicago and Milwaukee where the locomotive reached 125 mph (201 km/h) and sustained an average 120 mph (190 km/h) for 4.5 miles (7.2 km). However, the British locomotive LNER Class A4 4468 Mallard is officially accepted to be the world's fastest, with a run recorded at 125.88 mph (202.58 km/h) in 1938.

The Milwaukee F7s are accepted as the fastest steam locomotives by a different measure—scheduled speed between stations. In 1939, shortly after they were introduced into passenger service, the Twin Cities Hiawatha schedule was modified such that the engines would need to run the 78.3 mi (126.0 km) between Portage and Sparta, Wisconsin in 58 minutes—a start-to-stop average of 81 mph (130 km/h).

First-built #100 was also the first withdrawn from service, on November 10, 1949; last-built #105 was the final one in service, withdrawn August 10, 1951. All were scrapped.

Table of locomotives

Milwaukee Road No.	Alco serial No.	Built	Retired
100	69064	August 1938	November 1949
101	69065	August 1938	April 1951
102	69066	August 1938	August 1950
103	69067	August 1938	June 1951
104	69068	September 1938	June 1951
105	69069	September 1938	August 1951

See also

• CNW Class E-4 - nine very similar 4-6-4 locomotives built for the Milwaukee's Chicago competitor, the Chicago and North Western Railway.

References

Sources

External links

Media related to at Wikimedia Commons