Milwaukee Road class F7

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Milwaukee Road class F7
Kuhler-Hiaw.jpg
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 12 in (1,435 mm) standard gauge
Leading dia. 36 in (914 mm)
Driver dia. 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)
Total 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 20,000 US gal (75,700 l; 16,700 imp gal)
Firebox:
 • Firegrate area
96.5 sq ft (8.97 m2)
Boiler pressure 300 lbf/in2 (2.07 MPa)
Heating surface 4,166 sq ft (387.0 m2)
Superheater:
 • Type Type E
 • Heating area 1,695 sq ft (157.5 m2)
Cylinders Two, outside
Cylinder size 23 12 in × 30 in (597 mm × 762 mm)
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 ChicagoTwin 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).[1] However, the British locomotive LNER Class A4 4468 Mallard is officially accepted to be the world's fastest, with a run recorded at 126.1 mph (202.9 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).[1]

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[2][3]
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[edit]

References[edit]

  1. ^ a b Scribbins 1970, p. 63.
  2. ^ Edson 1977, p. 51.
  3. ^ Scribbins 1970, pp. 226–227.

Sources

External links[edit]

Media related to Milwaukee Road class F7 at Wikimedia Commons