Maine Central 2-6-6-2 "Mallet Mogul" Locomotives in the USA

Class Details by Steve Llanso of Sweat House Media

Class X (Locobase 6529)

Data from 1923 and 1924 Maine Central locomotive diagrams supplied by Allen Stanley in May 2005 from his extensive Rail Data Exchange. (Thanks to Bob Marville for his 30 September 2019 reporting a visit to the Bartlett, NH roundhouse, comments from which appear below.) Works numbers were 48648-48649.

These compound Mallets were delivered to the Boston & Maine as oil-burning helpers on the Hoosac Tunnel section. Within six months, however, that portion was electrified and the quartet was sold to the Maine Central. The B&M saw them go with few regrets, according to Drury (1993). They had small drivers and an equally small firebox. (The improbable values shown in the specs are clearly visible in the MEC's diagram. The MEC's calculated tractive effort was 61,860 lb.)

On the MEC they served on the Crawford Notch grade in New Hampshire. Within a year they'd been converted to coal burning. Bob Marville's visit on 28 September 2019 included a conversation with Cameron Sargent and Pete Davis, who he desribed as "part of the group restoring this gem [the roundhouse]." One of the features Sargent and Davis showed Marville were "where two stalls of the roundhouse had been extended to accommodate the mallet locomotives."

Despite the revised accommodations, the pair were rendered redundant by the introduction of 2-8-2s and the four worked only sporadically for years. The three unsuperheated engines were scrapped in 1929, while 1204, which had been superheated during repairs following an accident, lingered until 1934.

Principal Dimensions by Steve Llanso of Sweat House Media

Locobase ID6529
RailroadMaine Central (MEC)
Number in Class4
Road Numbers1201-1204
Number Built4
Valve GearWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft / m)22 / 6.71
Engine Wheelbase (ft / m)48.25 / 14.71
Ratio of driving wheelbase to overall engine wheelbase 0.46
Overall Wheelbase (engine & tender) (ft / m)77 / 23.47
Axle Loading (Maximum Weight per Axle) (lbs / kg)
Weight on Drivers (lbs / kg)262,000 / 118,841
Engine Weight (lbs / kg)308,000 / 139,707
Tender Loaded Weight (lbs / kg)148,300 / 67,268
Total Engine and Tender Weight (lbs / kg)456,300 / 206,975
Tender Water Capacity (gals / ML)7500 / 28.41
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT)12 / 11
Minimum weight of rail (calculated) (lb/yd / kg/m)73 / 36.50
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)61 / 1549
Boiler Pressure (psi / kPa)200 / 13.80
High Pressure Cylinders (dia x stroke) (in / mm)22" x 30" / 559x762
Low Pressure Cylinders (dia x stroke) (in / mm)35" x 30" / 889x762
Tractive Effort (lbs / kg)58,011 / 26313.38
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.52
Heating Ability
Tubes (number - dia) (in / mm)406 - 2" / 51
Flues (number - dia) (in / mm)
Flue/Tube length (ft / m)21 / 6.40
Firebox Area (sq ft / m2)169 / 15.70
Grate Area (sq ft / m2)49 / 4.55
Evaporative Heating Surface (sq ft / m2)4444 / 413.01
Superheating Surface (sq ft / m2)
Combined Heating Surface (sq ft / m2)4444 / 413.01
Evaporative Heating Surface/Cylinder Volume336.58
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation9800
Same as above plus superheater percentage9800
Same as above but substitute firebox area for grate area33,800
Power L13219
Power MT162.52

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Wes Barris