By the Union Pacific's reckoning, these "Overlands" (others called them "Southern Pacifics") weren't particularly successful engines. Their three-cylinder layout - outside actuated by Walschaert, inside by Gresley conjugated valve gear - was mechanically complicated and the wheelbase was too rigid. Yet, the even bigger 4-12-2s from dominating the prairies a few years later, which suggests that the Overlands suffered as much from being the pathfinders and a foreign road's design as anything else. See Locobase 288 for Alfred Bruce's assessment of the arrangement as it operated on the Espee.
They lasted on the LA&SL subsidiary until the late 1940s. By that time, they had been "remodeled" from a 3-cylinder to a 2-cylinder type, these measuring 27" diameter by 32" stroke.
| Specifications | |
|---|---|
| Class | FTT-1 |
| Locobase ID | 289 |
| Railroad | Union Pacific (UP) |
| Whyte | 4-10-2 |
| Road Numbers | 8000, 8800-8808 / 5090-99 |
| Gauge | Std |
| Builder | Alco-Brooks |
| Year | 1925 |
| Valve Gear | mixed |
| Locomotive Length and Weight | |
| Driver Wheelbase | 22.50' |
| Engine Wheelbase | 44.08' |
| Ratio of driving wheelbase to overall engine wheebase | 0.51 |
| Overall Wheelbase (engine & tender) | 82.42' |
| Axle Loading (Maximum Weight per Axle) | 60400 lbs |
| Weight on Drivers | 302000 lbs |
| Engine Weight | 404000 lbs |
| Tender Light Weight | 245500 lbs |
| Total Engine and Tender Weight | 649500 lbs |
| Tender Water Capacity | 12000 gals |
| Tender Fuel Capacity (oil/coal) | 5200 gals |
| Minimum weight per yard of rail on which locomotive could run | 101 lb rail |
| Geometry Relating to Tractive Effort | |
| Driver Diameter | 63" |
| Boiler Pressure | 210 psi |
| Cylinders (dia x stroke) | 25" x 30" (3) |
| Tractive Effort | 79688 lbs |
| Factor of Adhesion (Weight on Drivers/Tractive Effort) | 3.79 |
| Heating Ability | |
| Firebox Area | 357 sq. ft |
| Grate Area | 84 sq. ft |
| Evaporative Heating Surface | 5522 |
| Superheating Surface | 1375 |
| Combined Heating Surface | 6897 |
| Evaporative Heating Surface/Cylinder Volume | 215.99 |
| Computations Relating to Power Output (More Information) | |
| Robert LeMassena's Power Computation | 17640 |
| Same as above plus superheater percentage | 21168 |
| Same as above but substitute firebox area for grate area | 89964 |
| Power L1 | 16975 |
| Power MT | 619.59 |
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