Western Maryland 2-6-6-2 Locomotives of the USA

Class Details by Steve Llanso of Sweat House Media

Class M-1 (Locobase 8321)

Data from WM MISC steam locomotive diagram book supplied in May 2005 by Allen Stanley from his extensive Raildata collection. See also DeGolyer, Volume 41, pp. 328+. (Thanks to Chris Hohl for his 8 August 2016 email noting the original tender water capacity, incorrect building year and an apparent discrepancy between Baldwin and WM figures.) Works numbers were 33513-33514 in June 1909.

Comparisons with other 2-6-6-2s reveals that this design was virtually identical to that of the Great Northern's second batch of L-1s (Locobase 819), but with larger HP cylinders. Tender capacity later increased to 9,500 US gallons (35,980 litres) with a resulting loaded weight of 166,200 lb (75,387 kg).

Chris Hohl noted that the Baldwin's specs were considerably higher than those shown in Locobase. The Baldwin numbers are characterized with more than usual circumspection as "approximate". Also unusual was the large overestimate in both adhesion (estimated at 323,000 lb/146,511 kg) and engine weights (363,000lb/164,654 kg). Given the relative lack of experience with building large articulateds, it's possible that Baldwin was leaving itself some leeway.

Like the later Ls, these articulateds were dedicated to pusher service, which explains the lack of a superheater upgrade and the retention of slide valves.

According to Drury (1993), the class was converted to super-switchers (0-6-6-0s) in 1927-1931 that operated until scrapped in June 1944.

Class M-1a (Locobase 13938)

Data from WM MISC steam locomotive diagram book supplied in May 2005 by Allen Stanley from his extensive Raildata collection and Baldwin Locomotive Works Specification for Engines as digitized by the DeGolyer Library of Southern Methodist University, Volume 41, p. 331. Works numbers were 35300-35301 in October, 37140-37141 in October 1911, 37209-37211 in November 1911.

These were the slight enlargements of the design used in the 1909 pair of articulateds shown in Locobase 8321. Other than the small increase in boiler size caused by the inclusion of 13 more tubes, the two classes were essentially identical.

The specs include a proviso apparently meant to foreclose any underhanded substitution of inferior components: "Locos to be built in the best, most substantial and workmanlike manner according to the true intent and meaning of these specifications, which are intended to include everything requisite to the proper building of the engine, notwithstanding that everything required is not particularly mentioned in these specifications."

According to Drury (1993), the class was converted to super-switchers (0-6-6-0s) in 1927-1931 that operated into the late 1940s.

Specifications by Steve Llanso of Sweat House Media
Locobase ID8321 13,938
RailroadWestern Maryland (WM)Western Maryland (WM)
Number in Class27
Road Numbers951-952953-959
Number Built27
Valve GearWalschaertWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft)1010
Engine Wheelbase (ft)44.8345.33
Ratio of driving wheelbase to overall engine wheebase 0.22 0.22
Overall Wheelbase (engine & tender) (ft)78.4478.94
Axle Loading (Maximum Weight per Axle) (lbs)56,80061,000
Weight on Drivers (lbs)298,100310,000
Engine Weight (lbs)342,000354,000
Tender Loaded Weight (lbs)166,200166,200
Total Engine and Tender Weight (lbs)508,200520,200
Tender Water Capacity (gals)80009500
Tender Fuel Capacity (oil/coal) (gals/tons)1414
Minimum weight of rail (calculated) (lb/yd)8386
Geometry Relating to Tractive Effort
Driver Diameter (in)5555
Boiler Pressure (psi)200200
High Pressure Cylinders (dia x stroke) (in)23" x 32"23" x 32"
Low Pressure Cylinders (dia x stroke) (in)35" x 32"35" x 32"
Tractive Effort (lbs)73,08573,085
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.08 4.24
Heating Ability
Firebox Area (sq ft)225226
Grate Area (sq ft)7878
Evaporative Heating Surface (sq ft)56095766
Superheating Surface (sq ft)
Combined Heating Surface (sq ft)56095766
Evaporative Heating Surface/Cylinder Volume364.51374.71
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation15,60015,600
Same as above plus superheater percentage15,60015,600
Same as above but substitute firebox area for grate area45,00045,200
Power L134653548
Power MT153.75151.39



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