Firebox heating surface included 211 sq ft (19.6 sq m) of five thermic syphons and arch tubes; the long combustion chamber added considerable area as well. Lateral cushioning devices on each lead driver axle eased the locomotive into curves; the lead axle in the trailing truck also had one. Every axle on the engine and tender turned with roller bearings, which significantly reduced friction, the boiler's water came through Worthington feedwater heaters, coal appeared on the enormous grate from an HT-M automatic stoker, and 12" (305 mm) piston valves supplied steam to each of the four cylinders.
Drury (1993) says that "they were truly modern locomotives -- and they weren't what B&O wanted. The EM-1s probably wouldn't have been built but for the restrictions on diesels imposed by the War Production Board." On the other hand, they were very highly regarded engines that were the heaviest to be bought by the B&O, but among the lightest super-sized articulateds to be produced. They were, in fact almost 20 tons lighter on the drivers than the next heaviest engine (the Espee's AC-9 backup).
Despite the B&O's initially cool reception, the EM-1s soon established themselves as one of the premier articulateds in the East. In their initial assignments on the Cumberland and Pittsburgh Divisions and later on the ore-boat shuttles in northern Ohio, they proved powerful, quite reliable, and fast enough even to work an occasional passenger train. One less-obvious reason for this success was the relatively low boiler pressure setting, which raised the factor of adhesion. Some of the heavier coal and ore trains needed two EM-1s on the point and a third as pusher on the rear.
As dieselization progressed, the EM-1s were sidelined, being reawakened in several years to pick up the slack during times of heavy freight volume. The last retired in 1960.
|Specifications by Steve Llanso of Sweat House Media|
|Railroad||Baltimore & Ohio (B&O)|
|Number in Class||30|
|Locomotive Length and Weight|
|Ratio of driving wheelbase to overall engine wheebase||0.25|
|Overall Wheelbase (engine & tender)||112.50'|
|Axle Loading (Maximum Weight per Axle)||62100 lbs|
|Weight on Drivers||485000 lbs|
|Engine Weight||628700 lbs|
|Tender Light Weight||382000 lbs|
|Total Engine and Tender Weight||1010700 lbs|
|Tender Water Capacity||22000 gals|
|Tender Fuel Capacity (oil/coal)||25 tons|
|Minimum weight of rail (calculated)||101 lb/yard|
|Geometry Relating to Tractive Effort|
|Boiler Pressure||235 psi|
|Cylinders (dia x stroke)||24" x 32"|
|Tractive Effort||115056 lbs|
|Factor of Adhesion (Weight on Drivers/Tractive Effort)||4.22|
|Firebox Area||756 sq. ft|
|Grate Area||117.50 sq. ft|
|Evaporative Heating Surface||5298 sq. ft|
|Superheating Surface||2118 sq. ft|
|Combined Heating Surface||7416 sq. ft|
|Evaporative Heating Surface/Cylinder Volume||158.10|
|Computations Relating to Power Output (More Information)|
|Robert LeMassena's Power Computation||27613|
|Same as above plus superheater percentage||35620|
|Same as above but substitute firebox area for grate area||229181|