Railroad Gazette (3 August 1900) credits their design to Robert Quayle, then the Northwestern's Superintendent of Motive Power and Machinery. The journal called the engines "Northwesterns" and noted that although they'd been in service only a short time at time of writing, they were already proving much easier to fire than earlier locomotives. "The larger and better shaped grates and large heating surface make these very free-steaming engines. We are told that there is practically no black smoke, even when worked hard, and that the two doors are conducive to light firing."
They were also said to ride well.
This reflects the superheating applied to members of the large class of Atlantics profiled in Locobase 2793. The book does not say when this program was implemented nor how many D-class Atlantics were involved.
Larry Bohn, author of the website members.lsol.net/mollyandmic/c364.htm explains that these Omaha engines were very similar to the D-class Atlantics then being supplied to the Chicago & NorthWestern, the Omaha's parent. The data given here are after modification for superheating. Firebox heating surface includes 24.9 sq ft of arch tubes.
| Specifications | ||||
|---|---|---|---|---|
| Class | D | D - superheated | G-3 | G-3 - superheated |
| Locobase ID | 2793 | 4363 | 4855 | 9340 |
| Railroad | Chicago & North Western (C&NW) | Chicago & North Western (C&NW) | Chicago, St. Paul, Minneapolis & Omaha (C & NW) | Chicago, St. Paul, Minneapolis & Omaha (C & NW) |
| Whyte | 4-4-2 | 4-4-2 | 4-4-2 | 4-4-2 |
| Road Numbers | 364-370 | 364-370 | ||
| Gauge | Std | Std | Std | Std |
| Builder | Schenectady | shops | Schenectady | CStPMO |
| Year | 1900 | 1906 | 1906 | |
| Valve Gear | Stephenson | Walschaert | Stephenson | Stephenson |
| Locomotive Length and Weight | ||||
| Driver Wheelbase | 7' | 7' | 7' | 7' |
| Engine Wheelbase | 26.75' | 26.75' | 26.67' | 26.75' |
| Ratio of driving wheelbase to overall engine wheebase | 0.26 | 0.26 | 0.26 | 0.26 |
| Overall Wheelbase (engine & tender) | 57.94' | 57.94' | 57.90' | 57.94' |
| Axle Loading (Maximum Weight per Axle) | ||||
| Weight on Drivers | 91000 lbs | 97500 lbs | 91800 lbs | 92500 lbs |
| Engine Weight | 158000 lbs | 181500 lbs | 172000 lbs | 159500 lbs |
| Tender Light Weight | 140000 lbs | 144000 lbs | 144000 lbs | 144000 lbs |
| Total Engine and Tender Weight | 298000 lbs | 325500 lbs | 316000 lbs | 303500 lbs |
| Tender Water Capacity | 7500 gals | 7500 gals | 5200 gals | 5200 gals |
| Tender Fuel Capacity (oil/coal) | 10 tons | 10 tons | 10 tons | 10 tons |
| Minimum weight per yard of rail on which locomotive could run | 76 lb rail | 81 lb rail | 77 lb rail | 77 lb rail |
| Geometry Relating to Tractive Effort | ||||
| Driver Diameter | 80" | 81" | 81" | 81" |
| Boiler Pressure | 200 psi | 200 psi | 200 psi | 200 psi |
| Cylinders (dia x stroke) | 20" x 26" | 20" x 26" | 20" x 26" | 20" x 26" |
| Tractive Effort | 22100 lbs | 21827 lbs | 21827 lbs | 21827 lbs |
| Factor of Adhesion (Weight on Drivers/Tractive Effort) | 4.12 | 4.47 | 4.21 | 4.24 |
| Heating Ability | ||||
| Firebox Area | 199 sq. ft | 199 sq. ft | 195.60 sq. ft | 195.60 sq. ft |
| Grate Area | 46.30 sq. ft | 46.27 sq. ft | 46 sq. ft | 46.27 sq. ft |
| Evaporative Heating Surface | 3016 | 2174 | 2817 | 2174 |
| Superheating Surface | 439 | 439 | ||
| Combined Heating Surface | 3016 | 2613 | 2817 | 2613 |
| Evaporative Heating Surface/Cylinder Volume | 319.02 | 229.96 | 297.97 | 229.96 |
| Computations Relating to Power Output (More Information) | ||||
| Robert LeMassena's Power Computation | 9260 | 9254 | 9200 | 9254 |
| Same as above plus superheater percentage | 9260 | 11105 | 9200 | 11105 |
| Same as above but substitute firebox area for grate area | 39800 | 47760 | 39120 | 46944 |
| Power L1 | 11314 | 20335 | 10838 | 20286 |
| Power MT | 548.20 | 919.61 | 520.56 | 966.98 |
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