St Louis Southwestern 4-8-4 "Northern" Locomotives in the USA


Class Details by Steve Llanso of Sweat House Media

Class L1 - 800/GS-7 (Locobase 254)

Data from tables in the 1945 Locomotive Cyclopedia, supplemented by StL&SW 1 - 1932 Folio 725 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange and DeGolyer, Volume 82, pp. 492-538. See Joseph A Strapac, Cotton Belt Locomotives (Huntington Beach, Calif. : Shade Tree Books, 1977), pp. 126-128. Baldwin works numbers were 61421-61422, 61439-61442 in July 1930 and 61486-61489.

(Thanks to Robert Longhofer for his 26 June 2016 email noting the inaccurate assignment of th.e Pine Bluff shops to the Frisco; and Chris Hohl for his 5 July 2019 email reporting the class's engine & tender wheelbase Hohl's 10 September 2019 email reported the Cotton Belt's inquiry about a 2-8-4 design from Baldwin.)

Hohl's information includes a snippet of Strapac's description of the earlier proposal for Baldwin to build a Berkshire for them. The first version suggested a long-stroke cylinder and 70" drivers. The firebox had a 60" (1,524 mm) combustion chamber and a larger firebox. Tweaks included cutting the stroke by 2" (50.8 mm), reducing the boiler's size while lengthening the tubes and flues and elminating the two small sand domes. At that point, the SSW decided to go with a four-wheel leading truck and the result was the L1.

The firebox heating surface includes 107 sq ft (9.9 sq m) of thermic syphons (two in the firebox, one in the combustion chamber) and 104 sq ft (9.65 sq m) in the combustion chamber. Piston valves measured 14"(356 mm) in diameter. A Worthington Type S, No. 5, feed water heater had a rated maximum capacity of 75,000 lb (34,019 kg) or about 9,000 US gallons (34,065 litres) per hour.

The StL-SW diagram shows that of the driving wheelbase, only 12 feet 2 inches (3.7 m) was considered "rigid", meaning the lead driving axle had considerable lateral play. The frame and cylinders were combined in a integral steel casting. 800-804 truck bearings were Timken rollers while 805-809 ran SKFs. Later, all ten were refitted with Boxpok drivers, lightweight rods, and Timken roller bearings on all driving journals.

The first ten were built by Baldwin in 1930 and increased freight power by 30% while moving it faster. The specification noted that the maximum grade of 1.2% ran for 7,000 feet (2,134 m) and that the locomotive was "to handle maximum tonnage based on cylinder capacity and adhesive ratio with continuous pull of four miles [6.4 km] over continuous 1% grade at fifteen miles per hour minimum speed in addition to handling same load over above specified ruling grade [i.e. 1.2%] at same speed."

Pine Bluff, the Cotton Belt's main shop location, built its own variant; see Locobase 8479.

Seven of this class were leased to the Southern Pacific in late 1952. The Espee placed them in class GS-7 and used them on El Paso-San Antonio and on the Rio Grande Divisions. All of the class were scrapped by 1957.


Class L1 - 810 (Locobase 8479)

Data from tables in the 1930 Locomotive Cyclopedia, supplemented by StL&SW 1 - 1945 Folio 725 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange. (Thanks to Robert Longhofer for his 26 June 2016 email noting the inaccurate assignment of the Pine Bluff shops to the Frisco; and to Chris Hohl for his 24 May 2019 email noting the increase in weight of some of the class.)

The first ten Northerns on the StL-SW came from Baldwin in 1930 and they're described in Locobase 245. In this entry, we show the next five, which were produced by Pine Bluff, the Cotton Belt's main shop location in 1937. These had roller bearings on all axles and Boxpok drivers. Also, the superheater lost 98 sq ft (9.1 sq m) of heating surface, probably by eliminating elements from a few 3 1/2" flues, as the tube and flue counts remained the same at 52 and 200, respectively. The firebox heating surface included 107 sq ft (9.9 sq m) of thermic syphons (two in the firebox, one in the combustion chamber) and 104 sq ft (9.65 sq m) in the combustion chamber. Piston valves measured 14"(356 mm) in diameter. A Worthington Type S, No. 5, feed water heater had a rated maximum capacity of 75,000 lb (34,019 kg) or about 9,000 US gallons (34,065 litres) per hour.

The Baldwin engines were modified to a similar standard and Pine Bluff supplied another five engines with some minor changes and higher weights to support wartime traffic in 1942; see Locobase 16433.


Class L1 - 815 (Locobase 16433)

Chris Hohl's email led Locobase to look more closely at the 1945 diagram book, in which he found, to his surprise, two diagrams labeled 815-819. Comparing the two confirmed Hohl's report of a weight increase, which at first Locobase couldn't explain.

A couple of facts about this quintet explain the differences. One is the fact that the SSW couldn't persuade the War Production Board to supply them with five Electro-Motive Division FT freight diesel sets. So the railroad turned to its shops to add five more engines of the 810 class described in Locobase 8479. The first diagram shows the same data as the earlier 1937 engines, including their weights.And indeed virtually all of the specs, such as the 12" (305 mm) piston valves, Worthington Type 5-SA feed water heater, integral cast steel frame and cylinders, and Timken roller bearings on all axles, remained unchanged. A small change in the firebox reduced thermic syphon area by 4 sq ft to 103 sq ft (9.57 sq m).

But Locobase supposes that the shops couldn't use the same lightweight, high-strength steel components that held the adhesion weight in the 1937 locomotives to 248,000 lb. So, just as Baldwin's 2900 class 4-8-4s shown in Locobase 237 were the heaviest Santa Fe Northerns, so too the 815s took top place on the SSW. In the realm of US Northerns, however, even these heavyweights came in well down the list. Another increase was the cost of building this design, which increased from $110,969 for the 1937 locomotives to $143,607 in 1942.

The quintet served with the other Cotton Belt 4-8-4s into the 1950s. Of the twenty engines, four (813, 815, and 817-818) wound up on the Southern Pacific, which renumbered 4485-4488 in 1953. All but one were scrapped in 1955-1957. The exception was the last engine. 819, which was also the last steam locomotive built in Arkansas, was donated to its hometown on 22 July 1955. 28 years later, the locomotive was taken into the Pine Bluff shops in 1983 and restored to excursion service in 1986. In 1993, the locomotive was again retired and put back on display.

As of 2019, Project 819 was in the middle of restoring the 819 for a second time.

Principal Dimensions by Steve Llanso of Sweat House Media
ClassL1 - 800/GS-7L1 - 810L1 - 815
Locobase ID254 8479 16433
RailroadSt Louis Southwestern (Cotton Belt)St Louis Southwestern (Cotton Belt)St Louis Southwestern (Cotton Belt)
CountryUSAUSAUSA
Whyte4-8-44-8-44-8-4
Number in Class1055
Road Numbers800-809810-814815-819
GaugeStdStdStd
Number Built1055
BuilderBaldwinPine BluffPine Bluff
Year193019371942
Valve GearWalschaertWalschaertWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft / m)18.75 / 5.7118.75 / 5.7118.75 / 5.71
Engine Wheelbase (ft / m)45 / 13.7245 / 13.7245 / 13.72
Ratio of driving wheelbase to overall engine wheebase 0.42 0.42 0.42
Overall Wheelbase (engine & tender) (ft / m)87.58 / 26.6987.58 / 26.6987.58 / 26.69
Axle Loading (Maximum Weight per Axle) (lbs / kg)61,500 / 27,89662,000 / 28,12365,450 / 29,688
Weight on Drivers (lbs / kg)242,500 / 109,996248,000 / 112,491259,600 / 117,753
Engine Weight (lbs / kg)422,500 / 191,643425,500 / 193,004438,500 / 198,900
Tender Loaded Weight (lbs / kg)307,000 / 139,253312,000 / 141,521312,000 / 141,521
Total Engine and Tender Weight (lbs / kg)729,500 / 330,896737,500 / 334,525750,500 / 340,421
Tender Water Capacity (gals / ML)15,000 / 56.8215,000 / 56.8215,000 / 56.82
Tender Fuel Capacity (oil/coal) (gals/tons / ML/MT)5000 / 18.905000 / 18.905000 / 18.90
Minimum weight of rail (calculated) (lb/yd / kg/m)101 / 50.50103 / 51.50108 / 54
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)70 / 177870 / 177870 / 1778
Boiler Pressure (psi / kPa)250 / 17.20250 / 17.20250 / 17.20
High Pressure Cylinders (dia x stroke) (in / mm)26" x 30" / 660x76226" x 30" / 660x76226" x 30" / 660x762
Tractive Effort (lbs / kg)61,564 / 27924.9961,564 / 27924.9961,564 / 27924.99
Factor of Adhesion (Weight on Drivers/Tractive Effort) 3.94 4.03 4.22
Heating Ability
Firebox Area (sq ft / m2)469 / 43.57469 / 43.59465 / 43.20
Grate Area (sq ft / m2)88.30 / 8.2088.30 / 8.2188.30 / 8.20
Evaporative Heating Surface (sq ft / m2)4728 / 439.244728 / 439.414724 / 438.87
Superheating Surface (sq ft / m2)2060 / 191.381962 / 182.341962 / 182.27
Combined Heating Surface (sq ft / m2)6788 / 630.626690 / 621.756686 / 621.14
Evaporative Heating Surface/Cylinder Volume256.47256.47256.25
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation22,07522,07522,075
Same as above plus superheater percentage28,69828,47728,477
Same as above but substitute firebox area for grate area152,425151,253149,963
Power L140,52339,12839,090
Power MT1473.611391.331327.87

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