Chicago & North Western 2-8-4 "Berkshire" Type Locomotives

Class J-4 (Locobase 56)

Data from table in 1930 Locomotive Cyclopedia, supplemented by C & NW 10 - 1952 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive collection.

Firebox heating surface included 103 sq ft of thermic syphons and 21 sq ft of arch tubes, valve motion had limited cutoff in actuating 14" piston valves. The trailing truck wheels had two different diameters. The front axle turned 33" wheels, the rear 44" wheels.

Supplied in a batch built in Dunkirk (Brooks) in August 1927 (works #67372-67383), the class was assigned to coal trains on the Nelson-Peoria line.

Specifications

Class J-4

Locobase ID 56

Railroad Chicago & North Western (C&NW)

Whyte 2-8-4

Road Numbers 2801-2812

Gauge Std

Builder Alco-Brooks

Year 1927

Valve Gear Walschaert

Locomotive Length and Weight

Driver Wheelbase 16.80'

Engine Wheelbase 39.70'

Ratio of driving wheelbase to overall engine wheebase 0.42

Overall Wheelbase (engine & tender) 82.25'

Axle Loading (Maximum Weight per Axle)

Weight on Drivers 253500 lbs

Engine Weight 397000 lbs

Tender Light Weight 287000 lbs

Total Engine and Tender Weight 684000 lbs

Tender Water Capacity 15000 gals

Tender Fuel Capacity (oil/coal) 18 tons

Minimum weight per yard of rail on which locomotive could run 105.62 lb rail

Geometry Relating to Tractive Effort

Driver Diameter 63"

Boiler Pressure 240 psi

Cylinders (dia x stroke) 28" x 30"

Tractive Effort 76160 lbs

Factor of Adhesion (Weight on Drivers/Tractive Effort) 3.33

Heating Ability

Firebox Area 411 sq. ft

Grate Area 100.30 sq. ft

Evaporative Heating Surface 4777

Superheating Surface 2243

Combined Heating Surface 7020

Evaporative Heating Surface/Cylinder Volume 223.43

Computations Relating to Power Output (More Information)

Robert LeMassena's Power Computation 24072

Same as above plus superheater percentage 31763.38

Same as above but substitute firebox area for grate area 130157.03

Power L1 31846.11

Power MT 1107.83

Specifications
Class	J-4
Locobase ID	56
Railroad	Chicago & North Western (C&NW)
Whyte	2-8-4
Road Numbers	2801-2812
Gauge	Std
Builder	Alco-Brooks
Year	1927
Valve Gear	Walschaert
	Locomotive Length and Weight
Driver Wheelbase	16.80'
Engine Wheelbase	39.70'
Ratio of driving wheelbase to overall engine wheebase	0.42
Overall Wheelbase (engine & tender)	82.25'
Axle Loading (Maximum Weight per Axle)
Weight on Drivers	253500 lbs
Engine Weight	397000 lbs
Tender Light Weight	287000 lbs
Total Engine and Tender Weight	684000 lbs
Tender Water Capacity	15000 gals
Tender Fuel Capacity (oil/coal)	18 tons
Minimum weight per yard of rail on which locomotive could run	105.62 lb rail
	Geometry Relating to Tractive Effort
Driver Diameter	63"
Boiler Pressure	240 psi
Cylinders (dia x stroke)	28" x 30"
Tractive Effort	76160 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort)	3.33
	Heating Ability
Firebox Area	411 sq. ft
Grate Area	100.30 sq. ft
Evaporative Heating Surface	4777
Superheating Surface	2243
Combined Heating Surface	7020
Evaporative Heating Surface/Cylinder Volume	223.43
	Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation	24072
Same as above plus superheater percentage	31763.38
Same as above but substitute firebox area for grate area	130157.03
Power L1	31846.11
Power MT	1107.83

Reference

Chicago and Northwestern 1941-1953 by Lloyd Keyser
Chicago and North Western Power - Modern Steam and Diesel 1900 to 1971 by Patrick C. Dorin (Superior Publishing Co.)
Chicago and North Western Steam Power - 1848 - 1956 - Classes A - Z by Charles T. Knudsen (Knudsen Publications)
Zeppelins They Were Called, But Zeppelins They Were Not by Wallace W. Abbey in "Trains" October, 1970 page 20-33
Chicago & North Western Historical Society

Credits

Introduction and specifications provided by Steve Llanso of Sweat House Media.