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."
Hohl, citing Ecoff, noted that Molly and one of the Frisco's 2-10-2s were modified in the Sedalia shops in 1927. Among the changes, the most significant was the installation of Bethlehem tender truck booster engines on both trucks. This auxiliary engine was not unique to Molly, others having been installed in Lehigh & New England 2-10-0s (Locobases 65 and 14277) and 2-8-0s (Locobase 412), Lake Superior & Ishpeming 2-8-0s (Locobase 3295), Norfolk & Western Y-3 2-8-8-2 road number 2006 (Locobase 1421) Alton & Southern 0-10-0s (Locobse 13993) and 2-8-2 (Locobase 8318), Union Railroad 0-10-2 (Locobase 5976), and one of the L&N J-1A class of 2-8-2 (Locobase 8124), Pittsburgh & West Virginia's first three 2-6-6-4s (Locobase 301), and Lehigh Valley's T-1a 4-8-4s (Locobase 263)..
Hohl notes that the new tenders carried 15 tons of coal & 18,000 gallons of water. Ecoff's account said that the design included "automatic stokers and dual 10-inch diameter exhaust pipes for the boosters atop each end of the water space". In each three axle truck, two of the axles were connected by side rods.
The two boosters provided an additional 30,000 lbs in starting tractive effort for a estimated total of 124,000 lbs.). Ecoff added that in 1937, Molly's massive and headache producing tender was replaced by the tender from 4-6-2 # 6623
This tender rode on Commonwealth passenger trucks, used a new company-built tank, carried 16 tons of coa delivered by automatic stokerl & 10,000 gallons of water.
|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|