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

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)

Data from 1947 Locomotive Cyclopedia tables and ACL locomotive diagram books supplied in May 2005 by Allen Stanley from his extensive Raildata collection . Baldwin produced the class in two batches: works numbers 62174-62179 in March 1938 and 62180-62185 in May 1938.

Firebox was loaded with supplemental heating surface. In addition to the firebox area of 272 sq ft, R-1s had 127 sq ft in the combustion chamber and 168 sq ft in thermic syphons in both the firebox and combustion chamber.

The R-1s had all the latest features including cast-steel frame and roller bearings on the driving axles. But Baldwin overestimated the amount of counterbalancing these engines required, which led to pounding at high speeds. In fact, says, at high speed "...the main drivers actually left the rails and repeatedly slammed back down, kinking rails and damaging track alignment for miles." It took time, but eventually the solution was found in reducing the counterbalancing.

Six of the class (1800-1801, 1806-1809) ran even more smoothly once they were fitted with lightweight pistons by Timken, piston rods, cross heads, and, probably most important, tapered main rods with roller bearing wrist pins.

The website (consulted in Sept 2001) says that these engines easily hit 90 mph in passenger service and probably topped 100 at times. In fast freight service, an 1800 was rated at 6,200 tons on the Richmond-Jacksonville main line.

Don Ball (Portrait of the Rails, 1972) says: "An engine I regret never having seen ...This Baldwin, judging from photos, had to be about the most handsome steam power in the south." Retired in 1951-1952.

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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