Southern Pacific / Texas & New Orleans 4-4-2 "Atlantic" Type Locomotives

Class A (Locobase 4790)

Data from Scientific American - New York, May 20, 1905

story on modern high-speed engines. 292 was the single A, Harriman-design Atlantic obtained by the Chicago & Alton after its appearance at the 1904 St Louis Exposition. It quickly left C&A's employ, going into service with the Texas & New Orleans subsidiary of the Southern Pacific, where it joined three other Baldwin-built Atlantics. Drury (1993) describes the sale, but doesn't show the locomotive in his SP rosters.

It's larger than the other Harriman A-3 Atlantics. http://espee.railfan.net/sp_steam_a-03.html notes that this class received 77" drivers later in their careers and all were scrapped in 1937.

Class A-1 (Locobase 8658)

Data from T&NO 3 - 1932 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive collection.

This class went into service as five of the Southern Pacific's 12-locomotive A-1 Vauclain Compound Atlantics. They had two 15" HP and two 25" LP cylinders, all with 28" strokes, and stood on 84" drivers. Locobase presumes that they were converted to simple expansion at some point, some before and some after they were sold to the T & NO. (1 in 1906, 1 in 1908, 2 in 1912, and 1 in 1913).

In 1925, the T & NO took the quintet (which included 2 then attributed to the Galveston, Harrisburg & San Antonio) and superheated them, completing their transitions to local passenger engines. So modified, they served the T & NO through World War II before heading to the scrapyard in the period between September 1946 and May 1947.

Class A-1 - 278 (Locobase 8659)

Data from T&NO 3 - 1932 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive collection.

After the Southern Pacific sold several of its A-1 Vauclain Compound Atlantics to the T & NO, this engine suffered a boiler explosion in July 1913. The railway rebuilt it to the specs shown, a design that retained the high-speed aspirations of the original class (albeit with a reduction in driver diameter) but adopted simple-expansion and superheating.

This single-engine class carried on for the T & NO until April 1941.

Class A-3 (Locobase 1431)

Most numerous sub-class of the Espee A-class 4-4-2 series, these were Harriman Common Standard engines. Built by Alco (Schenectady and Brooks) and Baldwin from 1904 to 1908. Westcott (1960) says HCS Atlantics "were good performers, but slippery when starting and a little short on steam on sustained climbing." Given the relatively large boiler, one wonders if the shortness of breath could have come instead from the tall drivers. These would have allowed less steam per mile admitted to the cylinders than smaller-drivered engines. Westcott notes also that these engines could pull the Daylight Limited from Los Angeles to San Luis Obispo (223 miles) without refueling

All were superheated in the 1920s. Almost all received feedwater heaters or cast trailing trucks with starting booster engines. Unusually for modified engines, however, this class retained its inside Stephenson link motion. Four were modified by the railroad as A-6s; see Locobase 111.

Class A-3 - superheated (Locobase 8660)

Data from T&NO 3 - 1932 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive collection.

Superheating the Harriman Atlantics took several forms, including this variation by the T & NO's shops. This set of 4, which bore heralds from the Galveston, Harrisburg & San Antonio (290), Louisiana Western (291), and the Texas & New Orleans itself (289, 292), had fewer tubes than the A-5/A-6 (Locobase 6549 & 111, respectively) and had shorter drivers.

Class A-5 (Locobase 6549)

Data from SP Menke All-Time Steam Loco Diagrams supplied in May 2005 by Allen Stanley from his extensive collection.

These were built for the Mexican lines portion of the SP, later moving to the Arizona Eastern, and winding up on the Pacific Lines in 1924, where they ran until 1935.

Class A-6 (Locobase 111)

Data from SP Menke All-Time Steam Loco Diagrams supplied in May 2005 by Allen Stanley from his extensive collection.

Rebuilt from 4 Alco- and Baldwin-built A-3s (Locobase 1431). Fitted with 11,500-lb booster on trailing truck, which was modified to outside bearings. Also equipped with a Worthington feedwater heater.

Specifications
Class	A	A-1	A-1 - 278	A-3	A-3 - superheated	A-5	A-6
Locobase ID	4790	8658	8659	1431	8660	6549	111
Railroad	Texas & New Orleans (SP)	Texas & New Orleans (SP)	Texas & New Orleans (SP)	Southern Pacific (SP)	Texas & New Orleans (SP)	Southern Pacific (SP)	Southern Pacific (SP)
Whyte	4-4-2	4-4-2	4-4-2	4-4-2	4-4-2	4-4-2	4-4-2
Road Numbers	289-292	273-277	278	3025-3071	289-292	3072-3074	3000-3003
Gauge	Std	Std	Std	Std	Std	Std	Std
Builder	Burnham, Williams & Co	T & NO	T & NO	several	T & NO	Baldwin	Southern Pacific
Year	1904	1925	1914	1904	1904	1911	1927
Valve Gear	Stephenson	Walschaert	Stephenson	Stephenson	Stephenson	Walschaert	Walschaert
	Locomotive Length and Weight
Driver Wheelbase		7.25'	7.25'	7'	7'	7'	7'
Engine Wheelbase		29'	29'	27.58'	27.58'	27.58'	28.67'
Ratio of driving wheelbase to overall engine wheebase		0.25	0.25	0.25	0.25	0.25	0.24
Overall Wheelbase (engine & tender)				58.17'			78.70'
Axle Loading (Maximum Weight per Axle)		64500 lbs	64500 lbs		54000 lbs		64500 lbs
Weight on Drivers	145000 lbs	125000 lbs	124850 lbs	105000 lbs	107000 lbs	108000 lbs	126700 lbs
Engine Weight	221300 lbs	224400 lbs	225770 lbs	196000 lbs	199560 lbs	202500 lbs	243900 lbs
Tender Light Weight	166000 lbs			162200 lbs			174000 lbs
Total Engine and Tender Weight	387300 lbs	390400 lbs	390400 lbs	358200 lbs	390400 lbs	0	417900 lbs
Tender Water Capacity
Tender Fuel Capacity (oil/coal)
Minimum weight per yard of rail on which locomotive could run	121 lb rail	104 lb rail	104 lb rail	88 lb rail	89 lb rail	90 lb rail	106 lb rail
	Geometry Relating to Tractive Effort
Driver Diameter	80"	73"	77"	81"	77"	81"	81"
Boiler Pressure	200 psi	200 psi	200 psi	190 psi	200 psi	210 psi	210 psi
Cylinders (dia x stroke)	22" x 28"	20" x 28"	20" x 28"	20" x 28"	20" x 28"	20" x 28"	22" x 28"
Tractive Effort	28798 lbs	26082 lbs	24727 lbs	22331 lbs	24727 lbs	24681 lbs	29865 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort)	5.04	4.79	5.05	4.70	4.33	4.38	4.24
	Heating Ability
Firebox Area	202 sq. ft	185 sq. ft	179 sq. ft	174 sq. ft	174 sq. ft	176 sq. ft	176 sq. ft
Grate Area	49.50 sq. ft	46.60 sq. ft	49.50 sq. ft	49.50 sq. ft	49.50 sq. ft	49.50 sq. ft	49.50 sq. ft
Evaporative Heating Surface	3436	2405	2284	2649	2195	2305	2305
Superheating Surface		481	481		435	435	435
Combined Heating Surface	3436	2886	2765	2649	2630	2740	2740
Evaporative Heating Surface/Cylinder Volume	278.92	236.22	224.34	260.19	215.60	226.40	187.11
	Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation	9900	9320	9900	9405	9900	10395	10395
Same as above plus superheater percentage	9900	11184	11880	9405	11880	12474	12474
Same as above but substitute firebox area for grate area	40400	44400	42960	33060	41760	44352	44352
Power L1	9624	18305	18928	8866	17597	19770	16339
Power MT	292.65	645.69	668.47	372.31	725.13	807.14	568.61