Built with slide valves and Stephenson link motion; rebuilt with piston valves and Walschaerts valve motion.
In 1921, the GM&N sold these engines to the Louisville & Nashville (L&N) where they operated as K-6s until 1950-1951
Two built for the GM&N, which was later combined with the Mobile & Ohio as the GM&O. #425's history extends for decades. After the merger, she was renumbered 580.
She went to the Lousiana Eastern in 1950. In the early 1980s, she stored at the Wilmington & Western in Marshallton, DE, but never operated on those tracks because of her high axle loading. She then was moved to the Blue Mountain & Reading where she went into tourist service.
| Specifications | ||
|---|---|---|
| Class | 40 | 425 |
| Locobase ID | 2789 | 1315 |
| Railroad | Gulf, Mobile & Northern (GM&O) | Gulf, Mobile & Northern (GM&O) |
| Whyte | 4-6-2 | 4-6-2 |
| Road Numbers | 40-43 | 425-426 |
| Gauge | Std | Std |
| Builder | Baldwin | Baldwin |
| Year | 1912 | 1928 |
| Valve Gear | Walschaert | |
| Locomotive Length and Weight | ||
| Driver Wheelbase | 12' | 12.17' |
| Engine Wheelbase | 31.33' | 33.08' |
| Ratio of driving wheelbase to overall engine wheebase | 0.38 | 0.37 |
| Overall Wheelbase (engine & tender) | 62.83' | 65.79' |
| Axle Loading (Maximum Weight per Axle) | 44000 lbs | 43000 lbs |
| Weight on Drivers | 123000 lbs | 129000 lbs |
| Engine Weight | 198000 lbs | 213000 lbs |
| Tender Light Weight | 152400 lbs | 182000 lbs |
| Total Engine and Tender Weight | 350400 lbs | 395000 lbs |
| Tender Water Capacity | 7000 gals | 8500 gals |
| Tender Fuel Capacity (oil/coal) | 16 tons | 18 tons |
| Minimum weight per yard of rail on which locomotive could run | 68.33 lb rail | 71.67 lb rail |
| Geometry Relating to Tractive Effort | ||
| Driver Diameter | 69" | 69" |
| Boiler Pressure | 185 psi | 210 psi |
| Cylinders (dia x stroke) | 22" x 28" | 22" x 28" |
| Tractive Effort | 30885 lbs | 35058 lbs |
| Factor of Adhesion (Weight on Drivers/Tractive Effort) | 3.98 | 3.68 |
| Heating Ability | ||
| Firebox Area | 180 sq. ft | |
| Grate Area | 46.80 sq. ft | 54.20 sq. ft |
| Evaporative Heating Surface | 2480 | 2697 |
| Superheating Surface | 648 | 620 |
| Combined Heating Surface | 3128 | 3317 |
| Evaporative Heating Surface/Cylinder Volume | 201.31 | 218.93 |
| Computations Relating to Power Output (More Information) | ||
| Robert LeMassena's Power Computation | 8658 | 11382 |
| Same as above plus superheater percentage | 10451.60 | 13509.48 |
| Same as above but substitute firebox area for grate area | 40198.47 | 0 |
| Power L1 | 15909.04 | 0 |
| Power MT | 855.45 | 0 |
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