Boston, Clinton & Fitchburg 0-6-6 Locomotives in the USA

Class Details by Steve Llanso of Sweat House Media

Class Wm Mason (Locobase 5585)

Data from reproduction of 1950 reprint of 1883 Recent Locomotives as hosted by [] (visited 2 June 2003). See also "Some Old Mason Engines," Railroad & Locomotive Engineering , December 1900, p. 535. (Thanks to Chris Hohl for his 2 April 2023 email providing the various railroad name changes.) The boiler pressure is an estimate. Mason's works number was 536.

Ironhorse129's commentary notes that this was the first locomotive in the United States using Egide Walschaert's radial valve gear. Australian ferroequinologist and live-steam enthusiast David Fletcher wrote that the Stephenson gear normally used wouldn't work for an engine whose drivers pivoted on a bogie as this Mason Bogie did. The distance between the lifting rod, which controls cutoff, and the engineer's actuating Johnson bar would vary and the engine would speed up or slow down as a consequence. The Walschaert layout allowed for placing the lifting rod up in front of the steam dome in an arrangement that fixed the distance.

The writer of the RLE article praised the William Mason's pulling power, saying: "There is possibly no engine today, of her dimensions, that could, under the conditions of the day and time, equal this engine for the amount of work done. Had she not had a bogie of old design, the late J N Lauder would have repaired her .... The engine could haul 125 long freight box cars, such as were used at the time between Mansfield and Fitchburg, and the grades were heavy, so Mr Hobart Piper, her engineer, informs us. "

Chris Hohl documented the William Mason's several changes of ID: Ordered by the New Bedford Railroad, but delivered to the Boston, Clinton & Fitchburg #23 (the BC&F in was consolidated at the Boston, Clinton, Fitchburg & New Bedford in 1876.

The BCF&NB was absorbed by the Old Colony in 1883, which numbered the engine 108 At that time, the BCF&NB operated a total of 126.2 miles (203 km), which together with OCRR's mileage constituted the 617 miles (993 km).

Sources differ on the Wm Mason's fate. Some claim it remained on the OC roster at least until the OC merged with the New York, New Haven & Hartford. Those sources claim it took New Haven road #708. Locobase couldn't find any 0-6-6T in several New Haven rosters and considers it more likely that the OC scrapped soon after its 1883 takeover. Edson's New Haven roster shows the OC's motive power and reports the 108 as having been scrapped in 1887.

Another 0-6-6T, Canada Atlantic 724, was the first and only Mason Bogie to run on Canadian rails and the first Canadian engine to use Walschaert's gear. See [] . NB: For an explanation of the use of the singular "Walschaert", see Locobase 11157.

Principal Dimensions by Steve Llanso of Sweat House Media

ClassWm Mason
Locobase ID5585
RailroadBoston, Clinton & Fitchburg (New Haven)
Number in Class1
Road Numbers23/108/708
Number Built1
BuilderWilliam Mason
Valve GearWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft / m)8 / 2.44
Engine Wheelbase (ft / m)31 / 9.45
Ratio of driving wheelbase to overall engine wheelbase 0.26
Overall Wheelbase (engine & tender) (ft / m)31 / 9.45
Axle Loading (Maximum Weight per Axle) (lbs / kg)
Weight on Drivers (lbs / kg)66,600 / 30,209
Engine Weight (lbs / kg)73,928 / 33,533
Tender Loaded Weight (lbs / kg)
Total Engine and Tender Weight (lbs / kg)73,928
Tender Water Capacity (gals / ML)2530 / 9.58
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT)
Minimum weight of rail (calculated) (lb/yd / kg/m)37 / 18.50
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)42 / 1067
Boiler Pressure (psi / kPa)125 / 8.60
High Pressure Cylinders (dia x stroke) (in / mm)16" x 24" / 406x610
Tractive Effort (lbs / kg)15,543 / 7050.19
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.28
Heating Ability
Tubes (number - dia) (in / mm)154 - 2" / 51
Flues (number - dia) (in / mm)
Flue/Tube length (ft / m)11.50 / 3.51
Firebox Area (sq ft / m2)126 / 11.71
Grate Area (sq ft / m2)22.17 / 2.06
Evaporative Heating Surface (sq ft / m2)1053 / 97.86
Superheating Surface (sq ft / m2)
Combined Heating Surface (sq ft / m2)1053 / 97.86
Evaporative Heating Surface/Cylinder Volume188.37
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation2771
Same as above plus superheater percentage2771
Same as above but substitute firebox area for grate area15,750
Power L12634
Power MT261.58

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