The Mightiest of them All," T Greuter (http://www.trainweb.org/screamingeagle/mp4000.html). Works number was 37675
in April 1912.
A pretty large fish out of water, this single Mallet's boiler included 1,230 sq ft of feedwater heater. When 4000 arrived on the railroad, it almost immediately acquired a nickname - Molly - which reflected both the tendency of engine crews to think of their locomotives as iron women and a probable play on the usual pronunciation of Mallet ("Malley").
Molly ran on the StL & IM and the Missouri Pacific as a hump switcher until 1946. T. Greuter, writing on the Trainweb website, offered an affectionate description of Molly's career. First he tells us what she didn't do: "It is easy to imagine that such an impressive engine as Molly may have been put to use on the most powerful runs of the day, cresting the limestone rises of Kirkwood with a mile-long line of coal freight, but she didn't."
So, a grand vision, yes, but not what she did, as Greuter explains:
"The fact is Molly was a blue-collar worker, through and through. Her sheer massiveness made her ideally suited for effortlessly shuffling the high tonnage in endless strings of cars, breaking-up and building trains at Missouri Pacific's yard hump in St. Louis and Dupo, as well as tending transfer drags ... a sight that must have truely been awe inspiring to witness."
And, he notes, "Nothing else owned by the road approached her, Molly was the single one of her kind on the system."
|Principal Dimensions by Steve Llanso of Sweat House Media|
|Railroad||Saint Louis, Iron Mountain & Southern (MP)|
|Number in Class||1|
|Locomotive Length and Weight|
|Driver Wheelbase (ft / m)||15 / 4.57|
|Engine Wheelbase (ft / m)||56.58 / 17.25|
|Ratio of driving wheelbase to overall engine wheebase||0.27|
|Overall Wheelbase (engine & tender) (ft / m)||85.19 / 25.97|
|Axle Loading (Maximum Weight per Axle) (lbs / kg)|
|Weight on Drivers (lbs / kg)||395,000 / 179,169|
|Engine Weight (lbs / kg)||435,000 / 197,313|
|Tender Loaded Weight (lbs / kg)||160,000 / 72,575|
|Total Engine and Tender Weight (lbs / kg)||595,000 / 269,888|
|Tender Water Capacity (gals / ML)||8000 / 30.30|
|Tender Fuel Capacity (oil/coal) (gals/tons / ML/MT)||14 / 12.70|
|Minimum weight of rail (calculated) (lb/yd / kg/m)||82 / 41|
|Geometry Relating to Tractive Effort|
|Driver Diameter (in / mm)||55 / 1397|
|Boiler Pressure (psi / kPa)||200 / 13.80|
|High Pressure Cylinders (dia x stroke) (in / mm)||26" x 32" / 660x813|
|Low Pressure Cylinders (dia x stroke) (in / mm)||40" x 32" / 1016x813|
|Tractive Effort (lbs / kg)||94,007 / 42640.91|
|Factor of Adhesion (Weight on Drivers/Tractive Effort)||4.20|
|Firebox Area (sq ft / m2)||252 / 23.41|
|Grate Area (sq ft / m2)||84 / 7.80|
|Evaporative Heating Surface (sq ft / m2)||4533 / 421.13|
|Superheating Surface (sq ft / m2)||890 / 82.68|
|Combined Heating Surface (sq ft / m2)||5423 / 503.81|
|Evaporative Heating Surface/Cylinder Volume||230.52|
|Computations Relating to Power Output (More Information)|
|Robert LeMassena's Power Computation||16,800|
|Same as above plus superheater percentage||19,488|
|Same as above but substitute firebox area for grate area||58,464|