Maine Central 4-6-4 "Hudson" Locomotives of the USA

The Maine Central Railroad only bought two 4-6-4 Hudsons. This pair (road numbers 701 and 702) was built by the Baldwin Locomotive Works in 1930.

These locomotives had 73" drivers, 23" x 28" cylinders, a 240 psi boiler pressure, a total weight of 312,590 lbs and a tractive effort of 41,300 lbs.

Class Details by Steve Llanso of Sweat House Media

Class D (Locobase 1044)

Data from 1934 Maine Central locomotive tables and MEC-PTC 4 -1956 Locomotive Diagrams supplied by Allen Stanley in May 2005 from his extensive Raildata collection. See also DeGolyer, Volume 81, pp. 67+. (Thanks to Chris Hohl for his 26 February 2016 email adding the booster details.) Works numbers 61370-61371 in May 1930.

Pocket Hudsons, these were the lightest of the wheel arrangement. Their firebox heating surface included 14 sq ft (1.3 sq m) in two arch tubes and 74 sq ft (6.87 m) from two Nicholson thermic syphons. Piston valves measured 12" (306 mm) in diameter and reflected their "long-travel" description by shuttling 9" (229 mm) in each direction. The boiler also included a very high superheater surface area as a percentage of combined heating surface. The Franklin Type C-2-S boosters aided starting tractive effort.

Drury (1993) argues that traffic and economic conditions explain a) why the Maine Central went with Hudsons in the first place, and b) why they only bought two. They served until 1950 (701) and 1955 (702); the last few years of 702 were spent on least to the Portland Terminal Company.

Specifications by Steve Llanso of Sweat House Media
Locobase ID1044
RailroadMaine Central (MEC)
Number in Class2
Road Numbers701-702
Number Built2
Valve GearBaker
Locomotive Length and Weight
Driver Wheelbase13'
Engine Wheelbase35.67'
Ratio of driving wheelbase to overall engine wheebase 0.36
Overall Wheelbase (engine & tender)72.37'
Axle Loading (Maximum Weight per Axle)57600 lbs
Weight on Drivers171400 lbs
Engine Weight312590 lbs
Tender Light Weight189610 lbs
Total Engine and Tender Weight502200 lbs
Tender Water Capacity10000 gals
Tender Fuel Capacity (oil/coal)14 tons
Minimum weight of rail (calculated)95 lb/yard
Geometry Relating to Tractive Effort
Driver Diameter73"
Boiler Pressure240 psi
Cylinders (dia x stroke)23" x 28"
Tractive Effort41392 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.14
Heating Ability
Firebox Area306 sq. ft
Grate Area62.60 sq. ft
Evaporative Heating Surface3826 sq. ft
Superheating Surface1760 sq. ft
Combined Heating Surface5586 sq. ft
Evaporative Heating Surface/Cylinder Volume284.15
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation15024
Same as above plus superheater percentage19832
Same as above but substitute firebox area for grate area96941
Power L145967
Power MT1773.74



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