Oddball wheel arrangement was only one of the peculiarities of these two locomotives. Chief among them was the array of heating elements in the boilerThe evaporative heating surface area is shown in the specs. . A Jacobs smokebox superheater was squeezed in between the front face and the blast pipe; it offered very little extra energy to the steam it handled. Moreover, gases from the firebox passed through the flues, then reversed direction (!), traveling through a central flue and finally exit through the stack.
In addition, the combustion chamber held a Buck superheater-reheater combination that included 798 sq ft (74.14 sq m) of area through which the steam exhausting from the HP cylinders picked up some heat before entering the LP cylinders as well as a superheater in front of the reheater. See the AERJ article for a complete description.
In addition, the pair used the feedwater heating system briefly adopted on a few engines. In the 1398s, this bundle of 314 2 1/4" tubes, each 84" (2,134 mm) long, amounted to 1,279 sq ft (118.29 sq m).
Another rarity was the Jacobs-Shupert firebox, a stayless alternative described more fully in Locobase 463. Although all four cylinders used piston valves, HP valves measured 13"(330 mm) in diameter while the LP cylinders used 15" (381 mm) diameter valves. And the front adhesion wheelbase came to 6 ft 4 in (1,905 mm) while the three-axle wheelbase farther back was 12 ft 8 in (3,860 mm).
Noting that these oil-burners were intended for passenger work, Angus Sinclair's R&LE effused:"This engine unquestionably marks an epoch in the development of the American passenger locomotive." In addition to its size, the design combined "to a degree not heretofore attained, those features which have proved of great value in reducing fuel and water consumption."
True that, but in each instance, the actual superheater, feed water heater, combustion chamber were either dead-end variants or hopelessly compromised by other design elements. As a result, the duo was not successful in either passenger or freight service. Drury (1993) pronounced them "possibly the worst" of Santa Fe's Mallets. "The front (low-pressure) engine tended to slip, quickly using all the steam from the high-pressure engine, rendering itself useless and throwing all the load on the high-pressure engine."
But when converted to 4-6-2s in August and October 1915, respectively, along much more conventional lines, the pair served for decades (see Locobase 8274).
|Principal Dimensions by Steve Llanso of Sweat House Media|
|Railroad||Santa Fe (ATSF)|
|Number in Class||2|
|Locomotive Length and Weight|
|Driver Wheelbase (ft / m)||30.33 / 9.24|
|Engine Wheelbase (ft / m)||51.92 / 15.83|
|Ratio of driving wheelbase to overall engine wheebase||0.58|
|Overall Wheelbase (engine & tender) (ft / m)||94.46 / 28.79|
|Axle Loading (Maximum Weight per Axle) (lbs / kg)||59,000 / 26,762|
|Weight on Drivers (lbs / kg)||268,000 / 121,563|
|Engine Weight (lbs / kg)||376,450 / 170,755|
|Tender Loaded Weight (lbs / kg)||223,550 / 101,401|
|Total Engine and Tender Weight (lbs / kg)||600,000 / 272,156|
|Tender Water Capacity (gals / ML)||12,000 / 45.45|
|Tender Fuel Capacity (oil/coal) (gals/tons / ML/MT)||4000 / 15.20|
|Minimum weight of rail (calculated) (lb/yd / kg/m)||89 / 44.50|
|Geometry Relating to Tractive Effort|
|Driver Diameter (in / mm)||73 / 1854|
|Boiler Pressure (psi / kPa)||200 / 13.80|
|High Pressure Cylinders (dia x stroke) (in / mm)||24" x 28" / 610x711|
|Low Pressure Cylinders (dia x stroke) (in / mm)||38" x 28" / 965x711|
|Tractive Effort (lbs / kg)||53,697 / 24356.58|
|Factor of Adhesion (Weight on Drivers/Tractive Effort)||4.99|
|Firebox Area (sq ft / m2)||202 / 18.77|
|Grate Area (sq ft / m2)||52.50 / 4.88|
|Evaporative Heating Surface (sq ft / m2)||3477 / 323.02|
|Superheating Surface (sq ft / m2)||323 / 30.01|
|Combined Heating Surface (sq ft / m2)||3800 / 353.03|
|Evaporative Heating Surface/Cylinder Volume||237.16|
|Computations Relating to Power Output (More Information)|
|Robert LeMassena's Power Computation||10,500|
|Same as above plus superheater percentage||11,445|
|Same as above but substitute firebox area for grate area||44,036|