Data from DeGolyer, Vol 79, pp. 400+. Works numbers were 60515, 60540-60542 in June 1928 and 60581-60584 in August.
Using the same boiler and firebox as the slightly earlier three-cylinder Pacifics (Locobase 4428), Eddystone lengthened piston stroke and shrank the driver diameter to confer more tractive effort on these Mikados. Like the Pacifics, firebox heating surface area included 13 sq ft (1.2 sq m) of arch tubes, eight inch (203 mm) piston valves fed the cylinders, and a Worthington No 1 feed water heater was mounted on the left side.
| Principal Dimensions by Steve Llanso of Middle Run Media | |
|---|---|
| Class | 251 |
| Locobase ID | 15460 |
| Railroad | Manila Railroad |
| Country | Philippines |
| Whyte | 2-8-2 |
| Number in Class | 8 |
| Road Numbers | 251-258 |
| Gauge | 3'6" |
| Number Built | 8 |
| Builder | Baldwin |
| Year | 1928 |
| Valve Gear | Walschaert |
| Locomotive Length and Weight | |
| Driver Wheelbase (ft / m) | 13.25 / 4.04 |
| Engine Wheelbase (ft / m) | 27.58 / 8.41 |
| Ratio of driving wheelbase to overall engine wheelbase | 0.48 |
| Overall Wheelbase (engine & tender) (ft / m) | 56.42 / 17.20 |
| Axle Loading (Maximum Weight per Axle) (lbs / kg) | 25,760 / 11,685 |
| Weight on Drivers (lbs / kg) | 102,000 / 46,266 |
| Engine Weight (lbs / kg) | 143,000 / 64,864 |
| Tender Loaded Weight (lbs / kg) | 117,500 / 53,297 |
| Total Engine and Tender Weight (lbs / kg) | 260,500 / 118,161 |
| Tender Water Capacity (gals / ML) | 6000 / 22.73 |
| Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT) | 6 / 6 |
| Minimum weight of rail (calculated) (lb/yd / kg/m) | 43 / 21.50 |
| Geometry Relating to Tractive Effort | |
| Driver Diameter (in / mm) | 48 / 1219 |
| Boiler Pressure (psi / kPa) | 195 / 1340 |
| High Pressure Cylinders (dia x stroke) (in / mm) | 15" x 22" / 381x559 (3) |
| Tractive Effort (lbs / kg) | 25,639 / 11629.67 |
| Factor of Adhesion (Weight on Drivers/Tractive Effort) | 3.98 |
| Heating Ability | |
| Tubes (number - dia) (in / mm) | 136 - 2" / 51 |
| Flues (number - dia) (in / mm) | 24 - 5.375" / 137 |
| Flue/Tube length (ft / m) | 16 / 4.88 |
| Firebox Area (sq ft / m2) | 128 / 11.89 |
| Grate Area (sq ft / m2) | 33.20 / 3.08 |
| Evaporative Heating Surface (sq ft / m2) | 1800 / 167.22 |
| Superheating Surface (sq ft / m2) | 435 / 40.41 |
| Combined Heating Surface (sq ft / m2) | 2235 / 207.63 |
| Evaporative Heating Surface/Cylinder Volume | 266.69 |
| Computations Relating to Power Output (More Information) | |
| Robert LeMassena's Power Computation | 6474 |
| Same as above plus superheater percentage | 7704 |
| Same as above but substitute firebox area for grate area | 29,702 |
| Power L1 | 14,688 |
| Power MT | 1269.86 |