Milwaukee & Mississippi 4-4-0 "American" Locomotives in the USA

Class Details by Steve Llanso of Sweat House Media

Class Spring Green (Locobase 4907)

Another of the few locomotives produced by this New York builder, this engine had a long working life followed by a fortuitous preservation. On the website consulted in September 2001, Hume Kading reproduces the April 1994 (Vol VI, #4) El Paso & Southwestern Flyer newsletter article on this locomotive written by Charles P. Zlatkovich. Works number was 73 in May 1857.

Piecing together the data from this account and from John White's (1968) figure 63 gives us the dimensions and numbers we have. Like the Hudson River's Superior, the Spring Green rode on a slab-rail frame, rather than the far more common two-rail bar frame. A single deep rail ran from the smokebox to the first axle horn to which it was scarf-joined. Perhaps the Superior's tube-sheet weaknesses affected this design, for there are many fewer tubes in the slender boiler. A somewhat retrograde feature was the slanted cylinders, although in many other respects this was a state-of-the-art American design.

Zlatkovich says that the M&M is a predecessor of the later Milwaukee Road, although it went bankrupt soon after it purchased this engine. Reorganized as the Milwaukee & Prairie du Chien, it was then sold to the Milwaukee & St Paul in 1867. Arguing that the M&M named its locomotives after towns on the route, Zlatkovich is convinced by John H. White's suggestion that this engine was dubbed Spring Green rather than Spring Garden.

(Breese-Kneeland records show three more delivered to the M&M in the same month as the Spring Green. They may have been built to the same design and were named Auca, S J Collons, and Defiance.)

Southport was sold to the Arizona and South Eastern in 1889 (sources differ on whether it was February or July), EP&SW #1 operated until 1903, rostered until 1909, and restored for display in that year. EP&SW displayed the engine until 1960, when it was donated to Texas Western University and placed near the Centennial Museum.

NB: The direct heating surface (including the firebox heating surface) is an estimate calculated by subtracting the calculated tube heating surface from the reported total evaporative heating surface.

Principal Dimensions by Steve Llanso of Sweat House Media
ClassSpring Green
Locobase ID4907
RailroadMilwaukee & Mississippi
Number in Class1
Road Numbers40
Number Built1
Valve GearStephenson
Locomotive Length and Weight
Driver Wheelbase (ft / m) 6.79 / 2.07
Engine Wheelbase (ft / m)20.50 / 6.25
Ratio of driving wheelbase to overall engine wheebase 0.33
Overall Wheelbase (engine & tender) (ft / m)41.67 / 12.70
Axle Loading (Maximum Weight per Axle) (lbs / kg)
Weight on Drivers (lbs / kg)
Engine Weight (lbs / kg)52,000 / 23,587
Tender Loaded Weight (lbs / kg)
Total Engine and Tender Weight (lbs / kg)
Tender Water Capacity (gals / ML)
Tender Fuel Capacity (oil/coal) (gals/tons / ML/MT)
Minimum weight of rail (calculated) (lb/yd / kg/m)
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)64 / 1626
Boiler Pressure (psi / kPa)110 / 7.60
High Pressure Cylinders (dia x stroke) (in / mm)15" x 22" / 381x559
Tractive Effort (lbs / kg)7232 / 3280.38
Factor of Adhesion (Weight on Drivers/Tractive Effort)
Heating Ability
Firebox Area (sq ft / m2)77 / 7.16
Grate Area (sq ft / m2)
Evaporative Heating Surface (sq ft / m2)793 / 73.70
Superheating Surface (sq ft / m2)
Combined Heating Surface (sq ft / m2)793 / 73.70
Evaporative Heating Surface/Cylinder Volume176.23
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation
Same as above plus superheater percentage
Same as above but substitute firebox area for grate area8470
Power L13072
Power MT

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Wes Barris