Chicago & North Western / Chicago, St Paul, Minneapolis & Omaha 4-4-2 "Atlantic" Locomotives of the USA

Class Details by Steve Llanso of Sweat House Media

Class D (Locobase 2793)

Railroad Gazette (3 August 1900) credits their design to Robert Quayle, then the Northwestern's Superintendent of Motive Power and Machinery. Also see C&NW 1 -1927 Locomotive Diagrams supplied in May 2005 by Allen Stanley.

Works numbers were:

5613-5614 in July 1900; 5616-5618 in August; 5615 in September

5840-5841 in April 1901; 5842-5843 in May; 6138-6143 in December

25411-25412 in July 1902; 25413-25414 in August; 25415-25416 in October; 26524-26529 in December

25571-25579 in July 1903

29705-29708 in September 1904, 29709-29716 in October

30293 in January 1905, 30294-30297 in May, 30298 in June

39247-39256 in May 1906

42200-42209 in May 1907.

Acquisition of this relatively large class of Atlantics began with six in 1900 and continued for eight years. They had the relatively unusual layout of piston valves 11" (279 mm) in diameter between the frames and acuated by inside link motion. The trailing truck rode on outside-bearing journals topped by leaf springs. They also had 28.27 sq ft (2.6 sq m) of arch tubes.

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.

See Locobase 14674 for the last batch of Ds, ten of which were delivered with Walschaert gear actuating Young rotary valve gear.

Class D - late (Locobase 14674)

Data from American Locomotive Company negative S-589, a photograph of the 390 and data. Works numbers were 45697-45711 in December 1908.

Locobase 2793 describes the D class in toto from its beginnings in 1900. Because this last batch weighed quite a bit more because of the Walschaert gear installation, had slightly different surface areas and a small difference in driver diameter, we've created a separate entry. The last ten had Young rotary valves and Walschaert gear.

All of these were later superheated; see Locobase 4363.

Class D - superheated (Locobase 4363)

Data from 1927 C & NW locomotive diagram book supplied in May 2005 by Allen Stanley from his extensive Raildata collection.

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.

Class G-3 (Locobase 4855)

Larry Bohn, author of the website explains that these Omaha engines were very similar to the D-class Atlantics then being supplied to the Chicago & NorthWestern, the Omaha's parent. Works numbers were 38509-38512 in December 1905 and 39410-39412 in June 1906.

See Locobase 9340 for the superheated update.

Class G-3 - superheated (Locobase 9340)

Data from CStPM&O 4 - 1900 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Raildata collection.

Larry Bohn, author of the website 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 by Steve Llanso of Sweat House Media
ClassDD - lateD - superheatedG-3G-3 - superheated
Locobase ID2793 14,674 4363 4855 9340
RailroadChicago & North Western (C&NW)Chicago & North Western (C&NW)Chicago & North Western (C&NW)Chicago, St Paul, Minneapolis & Omaha (C&NW)Chicago, St Paul, Minneapolis & Omaha (C&NW)
Number in Class771477
Road Numbers125-128, 390-399364-370364-370
Number Built77147
Valve GearStephensonWalschaertWalschaertStephensonStephenson
Locomotive Length and Weight
Driver Wheelbase (ft)77777
Engine Wheelbase (ft)26.7526.7526.7526.6726.75
Ratio of driving wheelbase to overall engine wheebase 0.26 0.26 0.26 0.26 0.26
Overall Wheelbase (engine & tender) (ft)57.9458.6257.9457.9057.94
Axle Loading (Maximum Weight per Axle) (lbs)
Weight on Drivers (lbs)91,00095,00097,50091,80092,500
Engine Weight (lbs)158,000183,000181,500172,000159,500
Tender Loaded Weight (lbs)140,000144,300144,000144,000144,000
Total Engine and Tender Weight (lbs)298,000327,300325,500316,000303,500
Tender Water Capacity (gals)75007500750052005200
Tender Fuel Capacity (oil/coal) (gals/tons)1010101010
Minimum weight of rail (calculated) (lb/yd)7679817777
Geometry Relating to Tractive Effort
Driver Diameter (in)8081818181
Boiler Pressure (psi)200200200200200
High Pressure Cylinders (dia x stroke) (in)20" x 26"20" x 26"20" x 26"20" x 26"20" x 26"
Tractive Effort (lbs)22,10021,82721,82721,82721,827
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.12 4.35 4.47 4.21 4.24
Heating Ability
Firebox Area (sq ft)199197.10199195.60195.60
Grate Area (sq ft)46.3046.3046.274646.27
Evaporative Heating Surface (sq ft)30162956217428172174
Superheating Surface (sq ft)439439
Combined Heating Surface (sq ft)30162956261328172613
Evaporative Heating Surface/Cylinder Volume319.02312.68229.96297.97229.96
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation92609260925492009254
Same as above plus superheater percentage9260926010,827920010,827
Same as above but substitute firebox area for grate area39,80039,42046,56639,12045,770
Power L111,31411,25720,33510,83820,286
Power MT548.20522.47919.61520.56966.98


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