Data from MexRy 1939 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange.
At some point after the MR (Vera Cruz) took over the Pachuca & Tampico, whose origins are outlined in Locobase 6759, it apparently took care to upgrade the somewhat creaky locomotives it found on the roster. The 51 kept its original cylinder volume and driver diameters, but the newer vessel had fewer tubes (170 vs the original 200) and a higher boiler pressure (15 psi or 1.03 bar).
| Principal Dimensions by Steve Llanso of Middle Run Media | |
|---|---|
| Class | 51 |
| Locobase ID | 6739 |
| Railroad | Mexican |
| Country | Mexico |
| Whyte | 4-6-0 |
| Number in Class | 1 |
| Road Numbers | 51 |
| Gauge | Std |
| Number Built | |
| Builder | MR |
| Year | 1939 |
| Valve Gear | Stephenson |
| Locomotive Length and Weight | |
| Driver Wheelbase (ft / m) | 10.37 / 3.16 |
| Engine Wheelbase (ft / m) | 20.39 / 6.21 |
| Ratio of driving wheelbase to overall engine wheelbase | 0.51 |
| Overall Wheelbase (engine & tender) (ft / m) | 49.62 / 15.12 |
| Axle Loading (Maximum Weight per Axle) (lbs / kg) | |
| Weight on Drivers (lbs / kg) | 79,071 / 35,866 |
| Engine Weight (lbs / kg) | 105,138 / 47,690 |
| Tender Loaded Weight (lbs / kg) | 82,916 / 37,610 |
| Total Engine and Tender Weight (lbs / kg) | 188,054 / 85,300 |
| Tender Water Capacity (gals / ML) | 4500 / 17.05 |
| Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT) | 2850 / 10,787 |
| Minimum weight of rail (calculated) (lb/yd / kg/m) | 44 / 22 |
| Geometry Relating to Tractive Effort | |
| Driver Diameter (in / mm) | 56 / 1422 |
| Boiler Pressure (psi / kPa) | 160 / 1100 |
| High Pressure Cylinders (dia x stroke) (in / mm) | 17" x 24" / 432x610 |
| Tractive Effort (lbs / kg) | 16,845 / 7640.77 |
| Factor of Adhesion (Weight on Drivers/Tractive Effort) | 4.69 |
| Heating Ability | |
| Tubes (number - dia) (in / mm) | 170 - 2" / 51 |
| Flues (number - dia) (in / mm) | |
| Flue/Tube length (ft / m) | 12.31 / 3.75 |
| Firebox Area (sq ft / m2) | 145 / 13.47 |
| Grate Area (sq ft / m2) | 22 / 2.04 |
| Evaporative Heating Surface (sq ft / m2) | 1241 / 115.33 |
| Superheating Surface (sq ft / m2) | |
| Combined Heating Surface (sq ft / m2) | 1241 / 115.33 |
| Evaporative Heating Surface/Cylinder Volume | 196.67 |
| Computations Relating to Power Output (More Information) | |
| Robert LeMassena's Power Computation | 3520 |
| Same as above plus superheater percentage | 3520 |
| Same as above but substitute firebox area for grate area | 23,200 |
| Power L1 | 4653 |
| Power MT | 389.20 |