Atlantic Coast Line 4-8-4 "Northern" Locomotives of the USA

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Because of the growth of Florida tourism in the 1930s, the Atlantic Coast Line was experiencing a surge in its passenger business. To handle this heavy traffic, many of the main line trains were powered by 4-6-2 Pacifics pulling no more than 12 to 14 cars.

In 1937, the ACL received 12 new Class R-1 4-8-4s from the Baldwin Locomotive Works. They were assigned road numbers 1800 through 1811 and were immediately put into passenger service. These new 4-8-4s began to handle trains with as many as 21 heavyweight cars, eliminating the need for double-heading and running extra sections of many of the Richmond, VA to Jacksonville, FL "Specials".

The ACL was very disappointed with their R-1s, and returned them to Baldwin for better counterbalancing of the 80 inch drive wheels. It seems the R-1s, as delivered, had a bad dynamic augment. It was so bad that it was even worse than the Norfolk & Western's J class 4-8-4s with their low 70 inch drive wheels. Even after Baldwin checked their math, and put new disk drivers on the ACL R-1s, they still had unacceptable amounts of dynamic augment at high speeds. As soon as the ACL could replace them with EMD E-3 and E-6 diesel electrics, the Standard Railroad of the South put its latest and largest steamers in freight service.

Class Details by Steve Llanso of Sweat House Media

Class R-1 (Locobase 238)

Recent Construction #91 (Baldwin Locomotive Works, 1918), p. 28-29. See also DeGolyer, Volume 42, pp. 286-290 and 291-295. Works numbers were 38074 in July 1912; 38130-38132, 38167, 38186-38189, 38225-38228 in August; and 38281-38284, 38371-38373, 38382-38384, 38415-38416 in September..

Originally built by Great Northern with relatively tall drivers for a compound articulated. They presented an imposing appearance, showing a high Belpaire boiler over ten axles of running gear. Firebox heating surface included 81 sq ft (7.53 sq m) of combustion chamber, which was separated from the main firebox by a brick half wall. All four cylinders were fed through 15" (381 mm) piston valves.

The engines were big and superheated and presumably presented some new challenges. So the specs contain some "Hereafter" notes tweaking details. One, however, implied a higher level of urgency. Referring to a letter from F A Neely received on 3 November 1912, the note said "Give particular attention to riveting of cylinder saddles and caulking of same."

"Leaky seams" forced the railroad to remove lagging from all the boilers in the first batch save that of 2016 and caulk them. A least some high-pressure cylinders leaked and the flexible stay bolts at the back end of the combustion chamber either required redesign or at least more stays. (The firebox had 900 Tate flexible staybolts in all as well as 200 Tate expansion staybolts on the entire roof of the combustion chamber.)

The N-1s were simpled in the 1920s, becoming N-2s and later N-3s in the process (Locobases 2802 and 6445, respectively).

Specifications by Steve Llanso of Sweat House Media
Locobase ID238
RailroadAtlantic Coast Line (ACL)
Number in Class12
Road Numbers1800-1811
Number Built12
Valve GearWalschaert
Locomotive Length and Weight
Driver Wheelbase20.75'
Engine Wheelbase47.75'
Ratio of driving wheelbase to overall engine wheebase 0.43
Overall Wheelbase (engine & tender)97.92'
Axle Loading (Maximum Weight per Axle)65792 lbs
Weight on Drivers263127 lbs
Engine Weight460270 lbs
Tender Light Weight435000 lbs
Total Engine and Tender Weight895270 lbs
Tender Water Capacity24000 gals
Tender Fuel Capacity (oil/coal)27 tons
Minimum weight of rail (calculated)110 lb/yard
Geometry Relating to Tractive Effort
Driver Diameter80"
Boiler Pressure275 psi
Cylinders (dia x stroke)27" x 30"
Tractive Effort63901 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.12
Heating Ability
Firebox Area568 sq. ft
Grate Area97.75 sq. ft
Evaporative Heating Surface4753 sq. ft
Superheating Surface1425 sq. ft
Combined Heating Surface6178 sq. ft
Evaporative Heating Surface/Cylinder Volume239.08
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation26881
Same as above plus superheater percentage33064
Same as above but substitute firebox area for grate area192126
Power L137658
Power MT1262.08



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