Boston & Albany 4-6-6 Locomotives in the USA

Class Details by Steve Llanso of Sweat House Media

Class D-1A (Locobase 42)

Data from NYC 1 - 1946 Locomotive Diagram book supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange..(Many thanks to Chris Hohl for his 22 September 2017 email reporting unlikely boiler pressure values for 177 entries. A Locobase macro caused the error. His 31 December 2018 email also noted an incorrect track gauge entry.) Works numbers were 67609-67613 in September 1928.

Five large, high-boilered suburban passenger engines with fixed tender supported by three-axle trailing truck for running in both directions. Drury (1993) describes them as "big-boilered ...engines that looked like condensed, telescoped versions of parent NYC's Hudsons." The evidence also shows that they were derived from the earlier 2-6-6T D1s that were rebuilt by Lima in the late 1920s.

Chris Hohl points out that the engines later received thicker tires, which increased driver diameters to 64".

Alvin Staufer (Steam Power of the New York Central System, 1961) reported that they were "amazingly powerful and tireless for their size, capable of handling up to 20 steel coaches."

Noel Weaver, of Fort Lauderdale, Florida responded to a thread begun on [] (accessed 26 Sept 2005) with a post dated Wed Dec 22, 2004 2:57 am. In answer to the question that began the thread, Weaver said that this class "...operated mostly between Boston and Riverside via the Highland Branch and the main line. They probably also ran to Framingham on a more or less regular basis too. These were the RS-3's and GP-7's [all-purpose first-generation diesels] of the steam era as they could and did run quite well in reverse.

"They ran right up until the time that the diesels arrived maybe in the late 1940's or very early 1950's.

"I don't think they were regularly used anywhere else on the system after they were replaced by diesels in Boston."

eddiebear added on Wed Dec 22, 2004 7:57 am: "I think they might have gone to Milford too.

In one the TRAINS Album of New England Railroads, circa mid-1940s, there's a photo of one of them at speed on the Weston Park curve by the golf course west of Riverside."

Principal Dimensions by Steve Llanso of Sweat House Media
Locobase ID42
RailroadBoston & Albany (NYC)
Number in Class5
Road Numbers400-404
Number Built5
Valve GearBaker
Locomotive Length and Weight
Driver Wheelbase (ft / m)15 / 4.57
Engine Wheelbase (ft / m)42.66 / 13
Ratio of driving wheelbase to overall engine wheebase 0.35
Overall Wheelbase (engine & tender) (ft / m)42.66 / 13
Axle Loading (Maximum Weight per Axle) (lbs / kg)
Weight on Drivers (lbs / kg)180,000 / 81,647
Engine Weight (lbs / kg)352,000 / 159,665
Tender Loaded Weight (lbs / kg)
Total Engine and Tender Weight (lbs / kg)352,000
Tender Water Capacity (gals / ML)5000 / 18.94
Tender Fuel Capacity (oil/coal) (gals/tons / ML/MT)6 / 5.50
Minimum weight of rail (calculated) (lb/yd / kg/m)100 / 50
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)63 / 1600
Boiler Pressure (psi / kPa)215 / 14.80
High Pressure Cylinders (dia x stroke) (in / mm)23.5" x 26" / 597x660
Tractive Effort (lbs / kg)41,651 / 18892.60
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.32
Heating Ability
Firebox Area (sq ft / m2)213 / 19.79
Grate Area (sq ft / m2)60.80 / 5.65
Evaporative Heating Surface (sq ft / m2)2761 / 256.60
Superheating Surface (sq ft / m2)788 / 73.23
Combined Heating Surface (sq ft / m2)3549 / 329.83
Evaporative Heating Surface/Cylinder Volume211.53
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation13,072
Same as above plus superheater percentage15,948
Same as above but substitute firebox area for grate area55,870
Power L118,884
Power MT693.87

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Wes Barris