The reference for locomotives and railcars


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Chicago, Milwaukee, St. Paul & Pacific (Milwaukee Road) class F3
United States | 1910 | 70 produced
No. 156 in October 1938 in Minneapolis, Minnesota
No. 156 in October 1938 in Minneapolis, Minnesota
collection Taylor Rush

Although the Milwaukee Road had already procured its first few Pacifics in 1893, the Atlantics had still to pull the fastest trains for the time being. However, when they got problems with trains of ten to 14 cars, the 70 class F3 Pacifics were ordered from ALCO in 1910. They were initially operated with saturated steam and were retrofitted with superheaters from 1920 onwards. The diameter of the cylinders was increased from 23 to 23.5 inches, and for six of them even to 24 inches.

No. 152 with retrofitted streamlining in November 1953 in Madison, Wisconsin
No. 152 with retrofitted streamlining in November 1953 in Madison, Wisconsin
collection Taylor Rush

The locomotives were considered very powerful and well balanced. If necessary, they could reach up to 90 mph or 145 km/h. It wasn't until 1940 and 1941, when the Milwaukee Road was already using Hudsons, that three were rebuilt into the F3-as. The grate was widened and its area was significantly increased, but the direct heating surface of the firebox only grew slightly. Two of them were given streamlined fairing to pull the “Chippewa”.

Variantas builtsuperheatedrebuilt F3-as
Axle config4-6-2 (Pacific) 
Gauge4 ft 8 1/2 in (Standard gauge)
Dimensions and Weights
Wheelbase35 ft 7 in
Fixed wheelbase14 ft
Total wheelbase67 ft 2 in67 ft 4 1/2 in
Service weight247,300 lbs263,866 lbs284,300 lbs
Adhesive weight157,200 lbs169,380 lbs191,400 lbs
Total weight385,300 lbs419,866 lbs440,300 lbs
Axle load52,400 lbs56,460 lbs63,800 lbs
Water capacity7,000 us gal8,500 us gal
Fuel capacity20,000 lbs (coal)22,000 lbs (coal)26,000 lbs (coal)
Power sourcesteam
Estimated power1,900 hp (1,417 kW)2,200 hp (1,641 kW)2,400 hp (1,790 kW)
Optimal speed38 mph42 mph46 mph
Starting effort31,874 lbf33,275 lbf
Power Plant
Driver diameter79 in
Boiler pressure200 psi
Expansion typesimple
Cylinderstwo, 23 x 28 intwo, 23 1/2 x 28 in
Grate area48.8 sq ft59.8 sq ft
Firebox area266 sq ft275 sq ft
Tube heating area3,657 sq ft2,631 sq ft2,529 sq ft
Evaporative heating area3,923 sq ft2,897 sq ft2,804 sq ft
Superheater area620 sq ft
Total heating area3,923 sq ft3,517 sq ft3,424 sq ft
Calculated Values
steam locomotive
last changed: 03/2024

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