Northern Pacific / St Paul & Duluth 4-4-2 "Atlantic" Type Locomotives

Class N (Locobase 888)

Data from 1929 NP Locomotive Diagram book supplied in May 2005 from Allen Stanley from his extensive collection

Baldwin works #17290-17292. Taken onto the NP roster when that railroad acquired the Duluth & St. Paul.

Class N-1 (Locobase 889)

Three engines representing a relatively rare wheel arrangement for the NP. 603 was built by Baldwin, 604-605 by Alco. These joined three St. Paul and Duluth N-1s acquired in 1900. Data from 1929 NP Locomotive Diagram book supplied in May 2005 from Allen Stanley from his extensive collection applies to the two Alcos. Baldwin's 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 [sic], 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
Class	N	N-1
Locobase ID	888	889
Railroad	St Paul & Duluth (NP)	Northern Pacific (NP)
Whyte	4-4-2	4-4-2
Road Numbers	80-82 / 600-602	604-605
Gauge	Std	Std
Builder	Burnham, Williams & Co	Several
Year	1899	1909
Valve Gear	Stephenson	Walschaert
	Locomotive Length and Weight
Driver Wheelbase	7'	6.83'
Engine Wheelbase	25.08'	27.83'
Ratio of driving wheelbase to overall engine wheebase	0.28	0.25
Overall Wheelbase (engine & tender)	52.17'
Axle Loading (Maximum Weight per Axle)
Weight on Drivers	74600 lbs	100800 lbs
Engine Weight	140500 lbs	197050 lbs
Tender Light Weight	93200 lbs	127340 lbs
Total Engine and Tender Weight	233700 lbs	324390 lbs
Tender Water Capacity	4500 gals	6000 gals
Tender Fuel Capacity (oil/coal)	8 tons	9 tons
Minimum weight per yard of rail on which locomotive could run	62 lb rail	84 lb rail
	Geometry Relating to Tractive Effort
Driver Diameter	78"	73"
Boiler Pressure	180 psi	185 psi
Cylinders (dia x stroke)	19" x 26"	21" x 26"
Tractive Effort	18411 lbs	24699 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort)	4.05	4.08
	Heating Ability
Firebox Area
Grate Area	30 sq. ft	43.50 sq. ft
Evaporative Heating Surface	2429	2287
Superheating Surface		371
Combined Heating Surface	2429	2658
Evaporative Heating Surface/Cylinder Volume	284.69	219.42
	Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation	5400	8048
Same as above plus superheater percentage	5400	8852
Same as above but substitute firebox area for grate area	0	0
Power L1	0	0
Power MT	0	0