Boston & Albany 4-6-6 Locomotives of 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 Raildata collection.

Five large, high-boilered suburban passenger engines with fixed tender supported by 3-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.

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."

Specifications 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)15
Engine Wheelbase (ft)42.66
Ratio of driving wheelbase to overall engine wheebase 0.35
Overall Wheelbase (engine & tender) (ft)42.66
Axle Loading (Maximum Weight per Axle) (lbs)
Weight on Drivers (lbs)180,000
Engine Weight (lbs)352,000
Tender Loaded Weight (lbs)
Total Engine and Tender Weight (lbs)352,000
Tender Water Capacity (gals)5000
Tender Fuel Capacity (oil/coal) (gals/tons)6
Minimum weight of rail (calculated) (lb/yd)100
Geometry Relating to Tractive Effort
Driver Diameter (in)63
Boiler Pressure (psi)215
High Pressure Cylinders (dia x stroke) (in)23.5" x 26"
Tractive Effort (lbs)41,651
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.32
Heating Ability
Firebox Area (sq ft)213
Grate Area (sq ft)60.80
Evaporative Heating Surface (sq ft)2761
Superheating Surface (sq ft)788
Combined Heating Surface (sq ft)3549
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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