Data from the B&M 8 -1919 Locomotive classes book supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange.
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.
| Principal Dimensions by Steve Llanso of Middle Run Media | |
|---|---|
| Class | L1a/L1b |
| Locobase ID | 7342 |
| Railroad | Fitchburg (B&M) |
| Country | USA |
| Whyte | 4-8-0 |
| Number in Class | 18 |
| Road Numbers | 2900-2917 |
| Gauge | Std |
| Number Built | 18 |
| Builder | several |
| Year | 19 |
| Valve Gear | Stephenson |
| Locomotive Length and Weight | |
| Driver Wheelbase (ft / m) | 15.75 / 4.80 |
| Engine Wheelbase (ft / m) | 26.50 / 8.08 |
| Ratio of driving wheelbase to overall engine wheelbase | 0.59 |
| Overall Wheelbase (engine & tender) (ft / m) | 53.42 / 16.28 |
| Axle Loading (Maximum Weight per Axle) (lbs / kg) | |
| Weight on Drivers (lbs / kg) | 128,000 / 58,060 |
| Engine Weight (lbs / kg) | 168,000 / 76,204 |
| Tender Loaded Weight (lbs / kg) | 98,000 / 44,452 |
| Total Engine and Tender Weight (lbs / kg) | 266,000 / 120,656 |
| Tender Water Capacity (gals / ML) | 4500 / 17.05 |
| Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT) | 8 / 7 |
| Minimum weight of rail (calculated) (lb/yd / kg/m) | 53 / 26.50 |
| Geometry Relating to Tractive Effort | |
| Driver Diameter (in / mm) | 55 / 1397 |
| Boiler Pressure (psi / kPa) | 180 / 1240 |
| High Pressure Cylinders (dia x stroke) (in / mm) | 20" x 28" / 508x711 |
| Tractive Effort (lbs / kg) | 31,156 / 14132.14 |
| Factor of Adhesion (Weight on Drivers/Tractive Effort) | 4.11 |
| Heating Ability | |
| Tubes (number - dia) (in / mm) | 320 - 2" / 51 |
| Flues (number - dia) (in / mm) | |
| Flue/Tube length (ft / m) | 15 / 4.57 |
| Firebox Area (sq ft / m2) | 170 / 15.80 |
| Grate Area (sq ft / m2) | 29.90 / 2.78 |
| Evaporative Heating Surface (sq ft / m2) | 2673 / 248.42 |
| Superheating Surface (sq ft / m2) | |
| Combined Heating Surface (sq ft / m2) | 2673 / 248.42 |
| Evaporative Heating Surface/Cylinder Volume | 262.57 |
| Computations Relating to Power Output (More Information) | |
| Robert LeMassena's Power Computation | 5382 |
| Same as above plus superheater percentage | 5382 |
| Same as above but substitute firebox area for grate area | 30,600 |
| Power L1 | 5710 |
| Power MT | 393.39 |