Great Northern 4-4-2 "Atlantic" Type Locomotives

Class K-1 (Locobase 6945)

Data from GN 1916 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive collection. Works numbers were 28037-28038 in April 1906; 28078, 28092, 28107-28108, 28148, 28162, 28198, 28270 in May.

Drury (1993) notes that these were delivered in 1906 as balanced-compound engines. The 15" HP cylinders sat inside the frame and drove the first coupled axle; the 25" LP cylinders sat outside and drove the second. Drury's observation about their 73" drivers suggesting no great turn of speed bears remembering when the basic idea of the 4-4-2 arrangement was to provide more power to express passenger trains.

GN superheated these engines before 1916 beginning with 1706-1707. They were later simpled beginning in 1924; see Locobase 6944.

Class K-1-S (Locobase 6944)

Data from GN 1 -1929 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive collection.

When the GN converted their only Atlantics from balanced compounds to simple-expansion engines beginning in 1924, they created some big-boilered engines that got their steam through rather sizable 15" piston valves. (1709 was shown in a 1946 diagram book to have 10" piston valves.)

In the process, the road gained a set of useful, mid-sized passenger engines, albeit ones with pretty high axle loadings. At least 1 remained in service through World War II.

Specifications
Class	K-1	K-1-S
Locobase ID	6945	6944
Railroad	Great Northern (GN)	Great Northern (GN)
Whyte	4-4-2	4-4-2
Road Numbers	1700-1709	1700-1709
Gauge	Std	Std
Builder	Burnham, Williams & Co	GN
Year	1906	1924
Valve Gear	Walschaert	Walschaert
	Locomotive Length and Weight
Driver Wheelbase	7.12'	7.12'
Engine Wheelbase	30.37'	31.62'
Ratio of driving wheelbase to overall engine wheebase	0.23	0.23
Overall Wheelbase (engine & tender)	62.83'	62.83'
Axle Loading (Maximum Weight per Axle)	50000 lbs	62450 lbs
Weight on Drivers	100000 lbs	124900 lbs
Engine Weight	208000 lbs	227300 lbs
Tender Light Weight	148200 lbs	169560 lbs
Total Engine and Tender Weight	356200 lbs	396860 lbs
Tender Water Capacity	8000 gals	8000 gals
Tender Fuel Capacity (oil/coal)	18 tons	4500 gals
Minimum weight per yard of rail on which locomotive could run	83 lb rail	104 lb rail
	Geometry Relating to Tractive Effort
Driver Diameter	73"	73"
Boiler Pressure	210 psi	200 psi
Cylinders (dia x stroke)	15" x 26"	21" x 26"
Tractive Effort	21036 lbs	26702 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort)	4.75	4.68
	Heating Ability
Firebox Area	210.77 sq. ft	211 sq. ft
Grate Area	54.15 sq. ft	54.15 sq. ft
Evaporative Heating Surface	3489	2696
Superheating Surface		690
Combined Heating Surface	3489	3386
Evaporative Heating Surface/Cylinder Volume	656.10	258.66
	Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation	11372	10830
Same as above plus superheater percentage	11372	12996
Same as above but substitute firebox area for grate area	44262	50640
Power L1	7858	23255
Power MT	346.48	820.95