Data from DeGolyer, Volume 36, p. 173. Works numbers were 34778, 34881 in June 1910; 35113 in August; and 35629 in December.
This quartet of good-sized mixed-traffic engines went to the Noroeste just as the railway was opened between El Paso, Tex and destinations up to 150 miles south of the border.
Although the railway was a frequent target for raids during the Mexican Revolution, it survived well into the 20th Century. It would consolidate the Rio Grande, Sierra Madre & Pacific; the Chihuahua & Pacific; and the Sierra Madre & Pacific, which together amounted to 365 miles of track. By 1920, its main line measured 476 miles between El Paso and Chihuahua.
| Principal Dimensions by Steve Llanso of Middle Run Media | |
|---|---|
| Class | 41 |
| Locobase ID | 13724 |
| Railroad | Mexico North Western |
| Country | Mexico |
| Whyte | 4-6-0 |
| Number in Class | 4 |
| Road Numbers | 41-44 |
| Gauge | Std |
| Number Built | 4 |
| Builder | Baldwin |
| Year | 1910 |
| Valve Gear | Walschaert |
| Locomotive Length and Weight | |
| Driver Wheelbase (ft / m) | 14 / 4.27 |
| Engine Wheelbase (ft / m) | 24.75 / 7.54 |
| Ratio of driving wheelbase to overall engine wheelbase | 0.57 |
| Overall Wheelbase (engine & tender) (ft / m) | 53.75 / 16.38 |
| Axle Loading (Maximum Weight per Axle) (lbs / kg) | |
| Weight on Drivers (lbs / kg) | 113,000 / 51,256 |
| Engine Weight (lbs / kg) | 151,500 / 68,719 |
| Tender Loaded Weight (lbs / kg) | 125,000 / 56,699 |
| Total Engine and Tender Weight (lbs / kg) | 276,500 / 125,418 |
| Tender Water Capacity (gals / ML) | 6000 / 22.73 |
| Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT) | 12 / 11 |
| Minimum weight of rail (calculated) (lb/yd / kg/m) | 63 / 31.50 |
| Geometry Relating to Tractive Effort | |
| Driver Diameter (in / mm) | 62 / 1575 |
| Boiler Pressure (psi / kPa) | 180 / 1240 |
| High Pressure Cylinders (dia x stroke) (in / mm) | 20" x 26" / 508x660 |
| Tractive Effort (lbs / kg) | 25,665 / 11641.46 |
| Factor of Adhesion (Weight on Drivers/Tractive Effort) | 4.40 |
| Heating Ability | |
| Tubes (number - dia) (in / mm) | 320 - 2" / 51 |
| Flues (number - dia) (in / mm) | |
| Flue/Tube length (ft / m) | 14 / 4.27 |
| Firebox Area (sq ft / m2) | 155 / 14.40 |
| Grate Area (sq ft / m2) | 27 / 2.51 |
| Evaporative Heating Surface (sq ft / m2) | 2486 / 230.96 |
| Superheating Surface (sq ft / m2) | |
| Combined Heating Surface (sq ft / m2) | 2486 / 230.96 |
| Evaporative Heating Surface/Cylinder Volume | 263.07 |
| Computations Relating to Power Output (More Information) | |
| Robert LeMassena's Power Computation | 4860 |
| Same as above plus superheater percentage | 4860 |
| Same as above but substitute firebox area for grate area | 27,900 |
| Power L1 | 6418 |
| Power MT | 375.64 |