Seaboard Air Line 4-6-2 "Pacific" Type Locomotives

Class P (Locobase 2812)

Speedy Pacifics that proved to be a bit light. Baldwin built 5, Richmond turned out 15. The last of these lasted until 1951.

Much of the data comes from http://www.dnaco.net/~gelwood/other/sal-steambk.html for 1929 locomotive diagrams. Firebox heating surface includes 26 sq ft of arch tubes.

Superheat surface area is estimated from the calculation of the area of the flues and a calculated average ratio based on more than 350 locomotive entries in Locobase where both flue surface area and superheater areas are known. It's a close fit that likely slightly understates the real area.

Class P-1 (Locobase 1400)

Firebox heating surface includes 26 sq ft of arch tubes.

Much of the data comes from http://www.dnaco.net/~gelwood/other/sal-steambk.html for 1929 locomotive diagrams. Superheat surface area originally was estimated as 541 sq ft based on a calculation of the area of the flues and a calculated average ratio based on the hundreds of locomotive entries in Locobase where both flue surface area and superheater areas are known. Locobase figured it was a close fit that likely slightly understated the real area.

Data from reproduction of 1913 Alco Bulletin 1016 on Richard Leonard's http://www.railarchive.net/alcopacifics/index.html (accessed 16 June 2006) confirms that Locobase's calculation was correct in this instance by showing a value of 540 sq ft.

See Locobase for the P-2 69" drivered passenger variant.

Class P-2 (Locobase 8748)

Much of the data comes from http://www.dnaco.net/~gelwood/other/sal-steambk.html for 1929 locomotive diagrams. Although the first 15 locomotives of this design were delivered as P-1 mixed-traffic engines with 63" drivers (Locobase 1400), most were completed as 69"-drivered passenger engines.

Firebox heating surface includes 26 sq ft of arch tubes.

Specifications
Class	P	P-1	P-2
Locobase ID	2812	1400	8748
Railroad	Seaboard Air Line (SAL)	Seaboard Air Line (SAL)	Seaboard Air Line (SAL)
Whyte	4-6-2	4-6-2	4-6-2
Road Numbers	851-870	800-814	815-849
Gauge	Std	Std	Std
Builder	several	several	several
Year	1911	1912	1913
Valve Gear	Walschaert	Baker	Baker
	Locomotive Length and Weight
Driver Wheelbase	12.50'	12.50'	12.50'
Engine Wheelbase	32.75'	32.75'	32.75'
Ratio of driving wheelbase to overall engine wheebase	0.38	0.38	0.38
Overall Wheelbase (engine & tender)	66.25'	62.89'	62.89'
Axle Loading (Maximum Weight per Axle)	49700 lbs	49600 lbs	52164 lbs
Weight on Drivers	141500 lbs	142500 lbs	148690 lbs
Engine Weight	223000 lbs	220000 lbs	230600 lbs
Tender Light Weight	174300 lbs	151640 lbs	174300 lbs
Total Engine and Tender Weight	397300 lbs	371640 lbs	404900 lbs
Tender Water Capacity	9000 gals	8000 gals	9000 gals
Tender Fuel Capacity (oil/coal)	15 tons	14 tons	15 tons
Minimum weight per yard of rail on which locomotive could run	78.61 lb rail	79.17 lb rail	82.61 lb rail
	Geometry Relating to Tractive Effort
Driver Diameter	72"	63"	69"
Boiler Pressure	195 psi	185 psi	185 psi
Cylinders (dia x stroke)	23" x 28"	22" x 28"	22" x 28"
Tractive Effort	34098 lbs	33826 lbs	30885 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort)	4.15	4.21	4.81
	Heating Ability
Firebox Area	210 sq. ft	210 sq. ft	210 sq. ft
Grate Area	53.10 sq. ft	53.10 sq. ft	53.10 sq. ft
Evaporative Heating Surface	2820	2820	2820
Superheating Surface	541	540	540
Combined Heating Surface	3361	3360	3360
Evaporative Heating Surface/Cylinder Volume	209.44	228.91	228.91
	Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation	10354.50	9823.50	9823.50
Same as above plus superheater percentage	12021.20	11402.28	11402.28
Same as above but substitute firebox area for grate area	47541.48	45093.75	45093.75
Power L1	15187.55	13765.62	15076.63
Power MT	709.88	638.90	670.62