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|
|Railroad||Chicago & North Western (C&NW)|
|Locomotive Length and Weight|
|Ratio of driving wheelbase to overall engine wheebase||0.35|
|Overall Wheelbase (engine & tender)||88.98'|
|Axle Loading (Maximum Weight per Axle)|
|Weight on Drivers||216000 lbs|
|Engine Weight||412000 lbs|
|Tender Light Weight||360000 lbs|
|Total Engine and Tender Weight||772000 lbs|
|Tender Water Capacity||20000 gals|
|Tender Fuel Capacity (oil/coal)||25 tons|
|Minimum weight of rail (calculated) on which locomotive could run||120 lb/yard|
|Geometry Relating to Tractive Effort|
|Boiler Pressure||300 psi|
|Cylinders (dia x stroke)||25" x 29"|
|Tractive Effort||55022 lbs|
|Factor of Adhesion (Weight on Drivers/Tractive Effort)||3.93|
|Firebox Area||507 sq. ft|
|Grate Area||90.70 sq. ft|
|Evaporative Heating Surface||3958 sq. ft|
|Superheating Surface||1884 sq. ft|
|Combined Heating Surface||5842 sq. ft|
|Evaporative Heating Surface/Cylinder Volume||240.23|
|Computations Relating to Power Output (More Information)|
|Robert LeMassena's Power Computation||27210|
|Same as above plus superheater percentage||35917|
|Same as above but substitute firebox area for grate area||200772|