Data from "Mallet Articulated Compound Locomotives for the Nashville, Chatanooga & St Louis Railway", ,Railway Review, Volume 58, No 19 (6 May 1916), pp. 630-633; and NC&StL 6 - 1951 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange. See also DeGolyer, Volume 51, pp. 248+. (Thanks to Chris Hohl for his 12 January 2017 email noting the 14-ton tender capacity.) Works numbers were 42736, 42745-42746 in December 1915.
These engines had 41 sq ft (3.81 sq m) in four arch tubes and 116 sq ft (10.78 sq m) from the combustion chamber to contribute to firebox heating surface. Their steam distribution flowed through 15" (381 mm) balanced piston valves on both the HP cylinders and LP jugs.
The Baldwin specs show that the M-1-99s were required to pass through No. 6 Frogs and 16 degree 54 minute curves (399 foot; 142.9 metre radii).
Early diagram books show the center-to-center distance between the last set of drivers and their trailing trucks to be 7 ft 4 in, which taken with the other wheelbases, yields the 56 ft 10 in shown in Locobase's specs. Between 1934 and 1938, however, that distance was reduced to 6 ft 2 in, which shrank the total wheelbase to 55 ft 8 in (34.29 m). Externally, the change showed in the deletion of the forward side windows in the cab.
Fitted with Baldwin's flexible frame, M-1-99s could handle curves with a radius of 103 yards and were used as pushers over the Cumberland mountains on grades of up to 2.35%.
They were never converted to simple-expansion throughout their 30-year careers, which ended on the scrap heap in April 1945.
| Principal Dimensions by Steve Llanso of Middle Run Media | |
|---|---|
| Class | M-1-99 |
| Locobase ID | 322 |
| Railroad | Nashville, Chattanooga & St. Louis (NC&StL) |
| Country | USA |
| Whyte | 2-8-8-2 |
| Number in Class | 3 |
| Road Numbers | 900-902 |
| Gauge | Std |
| Number Built | 3 |
| Builder | Baldwin |
| Year | 1915 |
| Valve Gear | Walschaert |
| Locomotive Length and Weight | |
| Driver Wheelbase (ft / m) | 30 / 9.14 |
| Engine Wheelbase (ft / m) | 56.83 / 17.32 |
| Ratio of driving wheelbase to overall engine wheelbase | 0.53 |
| Overall Wheelbase (engine & tender) (ft / m) | 85.96 / 26.20 |
| Axle Loading (Maximum Weight per Axle) (lbs / kg) | |
| Weight on Drivers (lbs / kg) | 430,000 / 195,045 |
| Engine Weight (lbs / kg) | 470,000 / 213,189 |
| Tender Loaded Weight (lbs / kg) | 165,600 / 75,115 |
| Total Engine and Tender Weight (lbs / kg) | 635,600 / 288,304 |
| Tender Water Capacity (gals / ML) | 8500 / 32.20 |
| Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT) | 14 / 13 |
| Minimum weight of rail (calculated) (lb/yd / kg/m) | 90 / 45 |
| Geometry Relating to Tractive Effort | |
| Driver Diameter (in / mm) | 56 / 1422 |
| Boiler Pressure (psi / kPa) | 210 / 1450 |
| High Pressure Cylinders (dia x stroke) (in / mm) | 27" x 30" / 686x762 |
| Low Pressure Cylinders (dia x stroke) (in / mm) | 41" x 30" / 1041x762 |
| Tractive Effort (lbs / kg) | 97,248 / 44111.00 |
| Factor of Adhesion (Weight on Drivers/Tractive Effort) | 4.42 |
| Heating Ability | |
| Tubes (number - dia) (in / mm) | 253 - 2.25" / 57 |
| Flues (number - dia) (in / mm) | 43 - 5.5" / 140 |
| Flue/Tube length (ft / m) | 24 / 7.32 |
| Firebox Area (sq ft / m2) | 396 / 36.79 |
| Grate Area (sq ft / m2) | 85.50 / 7.94 |
| Evaporative Heating Surface (sq ft / m2) | 5448 / 506.13 |
| Superheating Surface (sq ft / m2) | 1240 / 115.20 |
| Combined Heating Surface (sq ft / m2) | 6688 / 621.33 |
| Evaporative Heating Surface/Cylinder Volume | 274.07 |
| Computations Relating to Power Output (More Information) | |
| Robert LeMassena's Power Computation | 17,955 |
| Same as above plus superheater percentage | 21,366 |
| Same as above but substitute firebox area for grate area | 98,960 |
| Power L1 | 7947 |
| Power MT | 325.96 |