Fitchburg 4-8-0 "Mastodon" Locomotives of the USA

Class Details by Steve Llanso of Sweat House Media

Class L1a/L1b (Locobase 7342)

Data from the B&M 8 -1919 Locomotive classes book supplied in May 2005 by Allen Stanley from his extensive Raildata collection.

Originally purchased as compounds by the Fitchburg, these Twelve-wheelers came from Schenectady (L-1a 1076-1085) in 1899 and the Rhode Island works in 1900 (L1b 1086-1093). They were soon simpled (1904) as shown and renumbered as 2900s. Although the 4-8-0 was not a very popular arrangement, it still wound up on a number of roads and the B & M kept its group until 1926.

An odd note in the class listing: The 1919 listing shows "Mastodons" with numbers 2900-2924, but no evidence otherwise of 2018-2024.

NB: The direct heating surface (including the firebox heating surface) is an estimate calculated by subtracting the calculated tube heating surface from the reported total evaporative heating surface.

Specifications by Steve Llanso of Sweat House Media
Locobase ID7342
RailroadFitchburg (B & M)
Number in Class18
Road Numbers2900-2917
Number Built18
Valve GearStephenson
Locomotive Length and Weight
Driver Wheelbase15.75'
Engine Wheelbase26.50'
Ratio of driving wheelbase to overall engine wheebase 0.59
Overall Wheelbase (engine & tender)53.42'
Axle Loading (Maximum Weight per Axle)
Weight on Drivers128000 lbs
Engine Weight168000 lbs
Tender Light Weight98000 lbs
Total Engine and Tender Weight266000 lbs
Tender Water Capacity4500 gals
Tender Fuel Capacity (oil/coal)8 tons
Minimum weight of rail (calculated)53 lb/yard
Geometry Relating to Tractive Effort
Driver Diameter55"
Boiler Pressure180 psi
Cylinders (dia x stroke)20" x 28"
Tractive Effort31156 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.11
Heating Ability
Firebox Area170 sq. ft
Grate Area29.90 sq. ft
Evaporative Heating Surface2673 sq. ft
Superheating Surface
Combined Heating Surface2673 sq. ft
Evaporative Heating Surface/Cylinder Volume262.55
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation5382
Same as above plus superheater percentage5382
Same as above but substitute firebox area for grate area30600
Power L15710
Power MT393.39


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