Data from Baldwin Locomotive Works Specification for Engines as digitized by the DeGolyer Library of Southern Methodist University, Volume 74, p. 395+. Works numbers were 57606-57607 in January 1924.
These steam trams clearly were based on an inspection engine design built in 1908 for the Guiler-Gordon Engineering company, which operated in Cuba (see Locobase 13280). The six-inch (152 mm) difference in gauge allowed the MA y T to use a slightly bigger grate, although its use of oil as a fuel made the firebox heating surface area more important. The two engines rode on 16 lb/yard (8 kg/metre) rail. As far as Locobase can determine, the power unit was independent of the tram car, to which it was coupled using a Baldwin CUH bull-nose link-and-pin coupler.
The line ran from Tlalnepantla, northeast of Mexico City proper, down to Azcapotzalco. Not long after the steam tram locomotives arrived, the tramway adopted gasoline power.
| Principal Dimensions by Steve Llanso of Middle Run Media | |
|---|---|
| Class | 6 |
| Locobase ID | 15334 |
| Railroad | Monte Alto y Tlalnepantla |
| Country | Mexico |
| Whyte | 2-2-0T |
| Number in Class | 2 |
| Road Numbers | 6-7 |
| Gauge | 3' |
| Number Built | 2 |
| Builder | Baldwin |
| Year | 1924 |
| Valve Gear | Stephenson |
| Locomotive Length and Weight | |
| Driver Wheelbase (ft / m) | |
| Engine Wheelbase (ft / m) | 6 / 1.83 |
| Ratio of driving wheelbase to overall engine wheelbase | |
| Overall Wheelbase (engine & tender) (ft / m) | 6 / 1.83 |
| Axle Loading (Maximum Weight per Axle) (lbs / kg) | |
| Weight on Drivers (lbs / kg) | 10,000 / 4536 |
| Engine Weight (lbs / kg) | 17,500 / 7938 |
| Tender Loaded Weight (lbs / kg) | |
| Total Engine and Tender Weight (lbs / kg) | 17,500 |
| Tender Water Capacity (gals / ML) | 300 / 1.14 |
| Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT) | 75 / 284 |
| Minimum weight of rail (calculated) (lb/yd / kg/m) | 17 / 8.50 |
| Geometry Relating to Tractive Effort | |
| Driver Diameter (in / mm) | 24 / 610 |
| Boiler Pressure (psi / kPa) | 150 / 1030 |
| High Pressure Cylinders (dia x stroke) (in / mm) | 6.5" x 10" / 165x254 |
| Tractive Effort (lbs / kg) | 2245 / 1018.32 |
| Factor of Adhesion (Weight on Drivers/Tractive Effort) | 4.45 |
| Heating Ability | |
| Tubes (number - dia) (in / mm) | 37 - 1.5" / 38 |
| Flues (number - dia) (in / mm) | |
| Flue/Tube length (ft / m) | 6 / 1.83 |
| Firebox Area (sq ft / m2) | 16 / 1.49 |
| Grate Area (sq ft / m2) | 3.85 / 0.36 |
| Evaporative Heating Surface (sq ft / m2) | 102 / 9.48 |
| Superheating Surface (sq ft / m2) | |
| Combined Heating Surface (sq ft / m2) | 102 / 9.48 |
| Evaporative Heating Surface/Cylinder Volume | 268.42 |
| Computations Relating to Power Output (More Information) | |
| Robert LeMassena's Power Computation | 578 |
| Same as above plus superheater percentage | 578 |
| Same as above but substitute firebox area for grate area | 2400 |
| Power L1 | 2874 |
| Power MT | 633.61 |