Oddball wheel arrangement was only one of the peculiarities of these two locomotives. Chief among them was the array of heating elements in the boiler. The evaporative heating surface area is shown in the specs. In addition, the combustion chamber held a Buck superheater-reheater combination that included 728 sq ft 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 413 2 1/4" tubes, each 6 ft 8 in (80") long, amounted to 678 sq ft
Another rarity was the Jacobs-Shupert firebox, a stayless alternative described more fully in Locobase 463.
Although all 4 cylinders used piston valves, those of the HP cylinders measured 13" in diameter while the LP cylinders used 15" diameter valves.
The engines were oil-fired and intended for passenger work, although they were not successful in either passenger or freight service. Drury (1993) pronounces 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."
Converted to 4-6-2s in 1915; see Locobase 8274.
| Specifications | |
|---|---|
| Class | 1398 |
| Locobase ID | 420 |
| Railroad | Santa Fe (ATSF) |
| Whyte | 4-4-6-2 |
| Road Numbers | 1398-1399 |
| Gauge | Std |
| Builder | Baldwin |
| Year | 1909 |
| Valve Gear | Walschaert |
| Locomotive Length and Weight | |
| Driver Wheelbase | 30.33' |
| Engine Wheelbase | 51.92' |
| Ratio of driving wheelbase to overall engine wheebase | 0.58 |
| Overall Wheelbase (engine & tender) | 94.46' |
| Axle Loading (Maximum Weight per Axle) | 59000 lbs |
| Weight on Drivers | 268016 lbs |
| Engine Weight | 376850 lbs |
| Tender Light Weight | 223550 lbs |
| Total Engine and Tender Weight | 600400 lbs |
| Tender Water Capacity | 12000 gals |
| Tender Fuel Capacity (oil/coal) | 4000 gals |
| Minimum weight per yard of rail on which locomotive could run | 89 lb rail |
| Geometry Relating to Tractive Effort | |
| Driver Diameter | 73" |
| Boiler Pressure | 200 psi |
| Cylinders (dia x stroke) | 24" x 28" |
| Low Pressure Cylinders (dia x stroke) | 38" x 28" |
| Tractive Effort | 53697 lbs |
| Factor of Adhesion (Weight on Drivers/Tractive Effort) | 4.99 |
| Heating Ability | |
| Firebox Area | 202 sq. ft |
| Grate Area | 52.70 sq. ft |
| Evaporative Heating Surface | 3477 |
| Superheating Surface | 328 |
| Combined Heating Surface | 3805 |
| Evaporative Heating Surface/Cylinder Volume | 237.16 |
| Computations Relating to Power Output (More Information) | |
| Robert LeMassena's Power Computation | 10540 |
| Same as above plus superheater percentage | 11489 |
| Same as above but substitute firebox area for grate area | 44036 |
| Power L1 | 4925 |
| Power MT | 202.56 |
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