Chicago & North Western 4-6-4 "Hudson" Locomotives of the USA

The Chicago & North Western bought nine Class E-4 oil burning Hudsons in 1938 from the American Locomotive Company and numbered them 4000 through 4008.

Class Details by Steve Llanso of Sweat House Media

Class E-4 (Locobase 180)

Data from tables in 1947 Locomotive Cyclopedia; see also C&NW 10-1952 Locomotive Diagrams. Works numbers ran 68982-28987 in March 1938; 68988-68989 and 69028 in April.

Firebox heating surface included 140 sq ft of thermic syphons and arch tubes. Developed for the Chicago-Minneapolis run (400 miles in 400 minutes) in competition with the Milwaukee Road's Hiawatha, which was pulled by either the A-class 4-4-2s or the F-7 class 4-6-4s. The C&NW locomotives were streamlined and painted green and yellow.

Their "physical attributes" were very similar to the Milwaukee's F-7s, which were also built by Alco in the same year (Locobase 183). One striking internal difference: The E-4 had only eight 2-inch tubes, which together with the 196 3 3/4" flues, made up much of her heating surface. This ratio of tube to flue is almost as far away from the usual balance as a standard boiler could get. By comparison, the F-7s had 220 more square feet, divided among 60 2 1/4" tubes and 164 3 1/2" flues, a more typical arrangement. The E-4s also had a 9% larger grate.

The E-4s used Baker valve gear to operated piston valves (12" or 14" in diameter). In 1946-1947, they were converted to oil-firing and trailed tenders carrying 20,000 US gallons (75,700 litres) of water and 6,000 gallons (22,710 litres) of oil fuel. They weighed 379,500 lb (172,139 kg).

Despite the difference, however, there appears to have been little difference in how these engines steamed, which underscores the custom-build tendency of steam locomotive manufacturers that ill-fitted them to compete with the standardized diesels. In fact, the E-4s were soon displaced by diesels and ran the transcontinental route from Chicago to Omaha.

Specifications by Steve Llanso of Sweat House Media
Locobase ID180
RailroadChicago & North Western (C&NW)
Number in Class9
Road Numbers4001-4009
Number Built9
Valve GearBaker
Locomotive Length and Weight
Driver Wheelbase14.67'
Engine Wheelbase42.33'
Ratio of driving wheelbase to overall engine wheebase 0.35
Overall Wheelbase (engine & tender)88.98'
Axle Loading (Maximum Weight per Axle)
Weight on Drivers216000 lbs
Engine Weight412000 lbs
Tender Light Weight360000 lbs
Total Engine and Tender Weight772000 lbs
Tender Water Capacity20000 gals
Tender Fuel Capacity (oil/coal)25 tons
Minimum weight of rail (calculated)120 lb/yard
Geometry Relating to Tractive Effort
Driver Diameter84"
Boiler Pressure300 psi
Cylinders (dia x stroke)25" x 29"
Tractive Effort55022 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort) 3.93
Heating Ability
Firebox Area507 sq. ft
Grate Area90.70 sq. ft
Evaporative Heating Surface3958 sq. ft
Superheating Surface1884 sq. ft
Combined Heating Surface5842 sq. ft
Evaporative Heating Surface/Cylinder Volume240.23
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation27210
Same as above plus superheater percentage35917
Same as above but substitute firebox area for grate area200772
Power L159775
Power MT1830.29



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