Missouri Pacific 2-8-4 "Berkshire" Type Locomotives

Class BK-63 (Locobase 1371)

Follow-ons to the Alcos of 1928 (Locobase 50) with these differences: 2 sand domes, full-length frame, Worthington BL feedwater heaters.

Firebox had thermic siphons, valve motion had limited cutoff. (Locobase uses an estimated value for the firebox heating surface based on the 1928 design's nearly identical specs.)

Similar to several other 2-8-4 classes built in the same half decade. These were converted to 75"-drivered 4-8-4s in 1940-1942.

Class none (Locobase 50)

Lloyd Stagner (Trains, November 1988) augments the data from the 1930 Locomotive Cyclopedia. Originally built for International-Great Northern subsidiary as 1121-1125, these were among the first wave of Berkshires. Firebox had two thermic syphons, valve motion had limited cutoff (60%); other goodies included the Worthington B1 feedwater heater, Chambers front-end throttle, Alco Type G power reversing gear, Franklin trailing-truck booster, and Dupont Simplex mechanical stoker. Stagner gives a firebox heating surface, including syphons, of 383 sq ft, which is the figure given in the MP's 1953ca Locomotive Diagrams book supplied in May 2005 by Allen Stanley from his extensive collection.

Stagner notes that they shared an uncluttered look with Chicago & North Western Berks bought in the same year. Their service on the "Jenny", which had mainlines from Longview, Texas to Palestine-San Antonio-Laredo and Palestine-Houston-Fort Worth. The design's lack of a combustion chamber conerned some.

Specifications
Class	BK-63	none
Locobase ID	1371	50
Railroad	Missouri Pacific (MP)	Missouri Pacific (MP)
Whyte	2-8-4	2-8-4
Road Numbers	1901-1925	1121-1125
Gauge	Std	Std
Builder	Lima	Alco
Year	1930	1928
Valve Gear		Walschaert
	Locomotive Length and Weight
Driver Wheelbase	16.80'	16.80'
Engine Wheelbase	42'	42'
Ratio of driving wheelbase to overall engine wheebase	0.40	0.40
Overall Wheelbase (engine & tender)	86.23'	86.23'
Axle Loading (Maximum Weight per Axle)
Weight on Drivers	267500 lbs	267500 lbs
Engine Weight	412000 lbs	404000 lbs
Tender Light Weight	310980 lbs
Total Engine and Tender Weight	722980 lbs	0
Tender Water Capacity	15000 gals	15000 gals
Tender Fuel Capacity (oil/coal)	18 tons	18 tons
Minimum weight per yard of rail on which locomotive could run	111.46 lb rail	111.46 lb rail
	Geometry Relating to Tractive Effort
Driver Diameter	63"	63"
Boiler Pressure	240 psi	240 psi
Cylinders (dia x stroke)	28" x 30"	28" x 30"
Tractive Effort	76160 lbs	76160 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort)	3.51	3.51
	Heating Ability
Firebox Area	415 sq. ft	415 sq. ft
Grate Area	100.30 sq. ft	100.30 sq. ft
Evaporative Heating Surface	5118 sq. ft	5118 sq. ft
Superheating Surface	2121 sq. ft	2121 sq. ft
Combined Heating Surface	7239 sq. ft	7239 sq. ft
Evaporative Heating Surface/Cylinder Volume	239.38	239.38
	Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation	24072	24072
Same as above plus superheater percentage	31125.01	31125.01
Same as above but substitute firebox area for grate area	128782.43	128782.43
Power L1	30977.44	30977.44
Power MT	1021.21	1021.21