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 Wheelbase (ft)15.75
Engine Wheelbase (ft)26.50
Ratio of driving wheelbase to overall engine wheebase 0.59
Overall Wheelbase (engine & tender) (ft)53.42
Axle Loading (Maximum Weight per Axle) (lbs)
Weight on Drivers (lbs)128,000
Engine Weight (lbs)168,000
Tender Loaded Weight (lbs)98,000
Total Engine and Tender Weight (lbs)266,000
Tender Water Capacity (gals)4500
Tender Fuel Capacity (oil/coal) (gals/tons)8
Minimum weight of rail (calculated) (lb/yd)53
Geometry Relating to Tractive Effort
Driver Diameter (in)55
Boiler Pressure (psi)180
High Pressure Cylinders (dia x stroke) (in)20" x 28"
Tractive Effort (lbs)31,156
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.11
Heating Ability
Firebox Area (sq ft)170
Grate Area (sq ft)29.90
Evaporative Heating Surface (sq ft)2673
Superheating Surface (sq ft)
Combined Heating Surface (sq ft)2673
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 area30,600
Power L15710
Power MT393.39


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