Fitchburg 4-4-0 "American" Locomotives of the USA

Class Details by Steve Llanso of Sweat House Media

Class Union (Locobase 13548)

Data from table entitled "Table of Dimensions of the Locomotives" in New England Association of Railway Superintendents, Report of the Trials of Locomotive Engines Made Upon 1st and 2nd October, 1851 (Boston: B J Yerrinton, Printers, 1852), p. 16.

The organizers of the 1851 trials expressed regret that some of the contestants supplied incomplete data for the table. The Union's entry reflects this lack. Enough was offered to show that this was an average-sized freight Eight-wheeler for the time.

The boiler pressure is the "effective pressure" as measured during the trials.

Specifications by Steve Llanso of Sweat House Media
Locobase ID13548
Number in Class1
Road Numbers
Number Built1
BuilderBoston Locomotive Works
Valve GearV-hook
Locomotive Length and Weight
Driver Wheelbase
Engine Wheelbase
Ratio of driving wheelbase to overall engine wheebase
Overall Wheelbase (engine & tender)
Axle Loading (Maximum Weight per Axle)
Weight on Drivers
Engine Weight46980 lbs
Tender Light Weight
Total Engine and Tender Weight
Tender Water Capacity
Tender Fuel Capacity (oil/coal)
Minimum weight of rail (calculated)0
Geometry Relating to Tractive Effort
Driver Diameter66"
Boiler Pressure97 psi
Cylinders (dia x stroke)16" x 20"
Tractive Effort6396 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort)
Heating Ability
Firebox Area
Grate Area 9.50 sq. ft
Evaporative Heating Surface
Superheating Surface
Combined Heating Surface0
Evaporative Heating Surface/Cylinder Volume
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation922
Same as above plus superheater percentage922
Same as above but substitute firebox area for grate area0
Power L10
Power MT

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