St Lawrence & Adirondack 4-8-0 "Mastodon" Locomotives in the USA

Class Details by Steve Llanso of Sweat House Media

Class S (Locobase 16551)

Data from TraitT pratique de la machine locomotive ... By Maurice Demoulin, 1898

Librairie polytechnique, Baudry et Cie, p 404-405. See also "Twelve-wheel Locomotive: St Lawrence & Adirondack Ry," Engineering News, Volume XXXV, No 25 (18 June 1896), pp. 405. Builder info from B.Rumary, 25 Kingscombe, Gurney Slade, Radstock, BA3 4TH, ENGLAND and Jeremy Lambert as supplied by Allen Stanley in March 2004. (Thanks to Chris Hohl for his 27 July 2021 email noting several differences in data in the original entry in Locobase 8884. Locobase realized that this entry needed to be split into two and created this entry to show the original St Lawrence & Adirondack engine.) Works number was 2667 in May 1896.

Purchase of a single Twelve-wheeler by the St Lawrence & Adirondack in May 1896 led to several dozen entering service on the BR&P. Although the StL&A went to the trouble of numbering (15) and naming their acquisition (Manitou), they sold the engine to the BR&P in November of the same year. In July 1897, Brooks built three more to an almost identical design (Locobase 8884).

The original quartet was sold in 1920 with 139 going to the Cumberland & Manchester as their #56.

Principal Dimensions by Steve Llanso of Sweat House Media

Locobase ID16551
RailroadSt Lawrence & Adirondack
Number in Class1
Road Numbers139
Number Built1
Valve GearStephenson
Locomotive Length and Weight
Driver Wheelbase (ft / m)15.50 / 4.72
Engine Wheelbase (ft / m)25.67 / 7.82
Ratio of driving wheelbase to overall engine wheelbase 0.60
Overall Wheelbase (engine & tender) (ft / m)51.48 / 15.69
Axle Loading (Maximum Weight per Axle) (lbs / kg)
Weight on Drivers (lbs / kg)140,500 / 63,730
Engine Weight (lbs / kg)172,000 / 78,018
Tender Loaded Weight (lbs / kg)96,000 / 43,545
Total Engine and Tender Weight (lbs / kg)268,000 / 121,563
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)59 / 29.50
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)55 / 1397
Boiler Pressure (psi / kPa)180 / 12.40
High Pressure Cylinders (dia x stroke) (in / mm)21" x 26" / 533x660
Tractive Effort (lbs / kg)31,896 / 14467.80
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.40
Heating Ability
Tubes (number - dia) (in / mm)324 - 2" / 51
Flues (number - dia) (in / mm)
Flue/Tube length (ft / m)12.50 / 3.81
Firebox Area (sq ft / m2)225 / 20.90
Grate Area (sq ft / m2)30.40 / 2.82
Evaporative Heating Surface (sq ft / m2)2331 / 216.56
Superheating Surface (sq ft / m2)
Combined Heating Surface (sq ft / m2)2331 / 216.56
Evaporative Heating Surface/Cylinder Volume223.70
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation5472
Same as above plus superheater percentage5472
Same as above but substitute firebox area for grate area40,500
Power L15473
Power MT343.51

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