Northern Pacific / St Paul & Duluth 4-4-2 "Atlantic" Locomotives of the USA


Class Details by Steve Llanso of Sweat House Media

Class N (Locobase 888)

Data from 1929 NP Locomotive Diagram book supplied in May 2005 from Allen Stanley from his extensive Raildata collection. See also Baldwin Locomotive Works Specification for Engines as digitized by the DeGolyer Library of Southern Methodist University, Volume 22, p179. Works numbers were 17290-17292 in December 1899.

Taken onto the NP roster when that railroad acquired the Skally Line, which was in 1900, the same year that this trio was delivered.

600 was scrapped in 1927, 601-602 went in 1932.


Class N-1 - 603 (Locobase 16056)

Data from DeGolyer, Volume 32, p. 81. (Thanks to Chris Hohl for his 7 April 2015 email correcting the builders ID, which led to research that led to this new entry.) Works numbers was 33292 in March 1909.

The main entry for this class is Locobase 889, which describes the two engines of this class that were delivered with superheaters.


Class N-1 - 603 superheated (Locobase 16057)

Data from 1929 NP Locomotive Diagram book supplied in May 2005 from Allen Stanley from his extensive Raildata collection. See also DeGolyer, Volume 32, p. 81. (Thanks to Chris Hohl for his 7 April 2015 email correcting the builders ID.) Works numbers were 33291-33293 in March 1909.

After Baldwin delivered three Atlantics to the Northern Pacific (Locobases 16056 and 889), the railroad chose to superheat this engine with a different distribution of small and large tubes from the two that were delivered by Baldwin with superheaters.


Class N-1 - 604-605 (Locobase 889)

Data from 1929 NP Locomotive Diagram book supplied in May 2005 from Allen Stanley from his extensive Raildata collection. See also DeGolyer, Volume 32, p. 81. (Thanks to Chris Hohl for his 7 April 2015 email correcting the builders ID.) Works numbers were 33291-33293 in March 1909.

Three engines representing a relatively rare wheel arrangement for the NP. These joined three St. Paul and Duluth N-1s acquired in 1900. This spec applies to the two Baldwins that were delivered with superheaters and 12" (305 mm) piston valves; 603 originally arrived with a saturated boiler; see Locobase 16056.

When superheated, 603 had 2,251 sq ft of EHS, 437 sq ft of SHS; tube and flue counted came to 185 2" tubes and 24 5 3/8" flues.

RV Nixon, in the Northern Pacific's Tell Tale (September, 1950) (http://www.employees.org/~davison/nprha/niftyfiftytelltale.html) gave an account of these rare birds:

"In the 1890s and early 1900s most of the railroads went overboard buying Atlantic or 4-4-2 type locomotives, particularly lines in the East where easy grades prevailed. The Atlantic was great for speed and low in tractive effort ...

"Northern Pacific, however, used good judgment in not falling for the Atlantic fad. Heavy trains, mountain grades and Atlantics were not a good combination. Only three engines of this type, 603-605, built by Baldwin in 1909, were purchased by the Northern Pacific. Three others, Class N, were taken over by the Northern Pacific when the St. Paul and Duluth Railroad was absorbed"

Nixon adds that many long-time NP employees never knew that Atlantics ran on their railroad. He supposes the explanation "...probably is due to the fact that the Atlantics, as far as we know, never worked west of Mandan. For the most part they were used on branches out of Mandan and Jamestown, as well as on the lines from Staples and St. Paul to Duluth ...."

Specifications by Steve Llanso of Sweat House Media
ClassNN-1 - 603N-1 - 603 superheatedN-1 - 604-605
Locobase ID888 16,056 16,057 889
RailroadSt Paul & Duluth (NP)Northern Pacific (NP)Northern Pacific (NP)Northern Pacific (NP)
CountryUSAUSAUSAUSA
Whyte4-4-24-4-24-4-24-4-2
Number in Class3112
Road Numbers80-82 / 600-602603603604-605
GaugeStdStdStdStd
Number Built312
BuilderBurnham, Williams & CoBurnham, Williams & CoNPBurnham, Williams & Co
Year1899190919091909
Valve GearStephensonWalschaertWalschaertWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft)7 6.83 6.83 6.83
Engine Wheelbase (ft)25.0827.8327.8327.83
Ratio of driving wheelbase to overall engine wheebase 0.28 0.25 0.25 0.25
Overall Wheelbase (engine & tender) (ft)52.1757.25
Axle Loading (Maximum Weight per Axle) (lbs)
Weight on Drivers (lbs)74,600100,000100,800100,800
Engine Weight (lbs)140,500180,000197,050197,050
Tender Loaded Weight (lbs)93,200122,800127,340127,340
Total Engine and Tender Weight (lbs)233,700302,800324,390324,390
Tender Water Capacity (gals)4500600060006000
Tender Fuel Capacity (oil/coal) (gals/tons)8999
Minimum weight of rail (calculated) (lb/yd)62838484
Geometry Relating to Tractive Effort
Driver Diameter (in)78737373
Boiler Pressure (psi)180185185185
High Pressure Cylinders (dia x stroke) (in)19" x 26"21" x 26"21" x 26"21" x 26"
Tractive Effort (lbs)18,41124,69924,69924,699
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.05 4.05 4.08 4.08
Heating Ability
Firebox Area (sq ft)171168168168
Grate Area (sq ft)30.1043.5043.5043.50
Evaporative Heating Surface (sq ft)2217271822512287
Superheating Surface (sq ft)437371
Combined Heating Surface (sq ft)2217271826882658
Evaporative Heating Surface/Cylinder Volume259.84260.77215.97219.42
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation5418804880488048
Same as above plus superheater percentage5418804893359174
Same as above but substitute firebox area for grate area30,78031,08036,05335,431
Power L18425768415,16813,963
Power MT497.96338.81663.49610.78

Reference


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