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 13938
RailroadWestern Maryland (WM)Western Maryland (WM)
Number in Class27
Road Numbers951-952953-959
Number Built27
Valve GearWalschaertWalschaert
Locomotive Length and Weight
Driver Wheelbase10'10'
Engine Wheelbase44.83'45.33'
Ratio of driving wheelbase to overall engine wheebase 0.22 0.22
Overall Wheelbase (engine & tender)78.44'78.94'
Axle Loading (Maximum Weight per Axle)56800 lbs61000 lbs
Weight on Drivers298100 lbs310000 lbs
Engine Weight342000 lbs354000 lbs
Tender Light Weight166200 lbs166200 lbs
Total Engine and Tender Weight508200 lbs520200 lbs
Tender Water Capacity8000 gals9500 gals
Tender Fuel Capacity (oil/coal)14 tons14 tons
Minimum weight of rail (calculated)83 lb/yard86 lb/yard
Geometry Relating to Tractive Effort
Driver Diameter55"55"
Boiler Pressure200 psi200 psi
High Pressure Cylinders (dia x stroke)23" x 32"23" x 32"
Low Pressure Cylinders (dia x stroke)35" x 32" (2)35" x 32" (2)
Tractive Effort73085 lbs73085 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.08 4.24
Heating Ability
Firebox Area225 sq. ft226 sq. ft
Grate Area78 sq. ft78 sq. ft
Evaporative Heating Surface5609 sq. ft5766 sq. ft
Superheating Surface
Combined Heating Surface5609 sq. ft5766 sq. ft
Evaporative Heating Surface/Cylinder Volume364.51374.71
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation1560015600
Same as above plus superheater percentage1560015600
Same as above but substitute firebox area for grate area4500045200
Power L134653548
Power MT153.75151.39



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