Data from "Locomotives for the Indian Metre Gauge Rys", The Locomotive Magazine, Vol VI (February 1901), p. 50.
The LM author tells us that the O-class passenger engines shown here and the F-class goods engines described in Locobase 10181 were standard metre-gauge locomotives for the Indian State Railways as well as many other private lines. O-class engines were built from 1883 to 1912; this variant thus falls in the middle of the period.
To allow the largest possible grate within the confines of a narrow loading gauge, the plate frames lay outside of the wheels. Such placement in turn required the use of fly cranks to take the connecting rod's (main rod's) thrust and these also acted as the journals within the axle boxes. Boilers could be round-top or Belpaire; the locomotive described in the specs had a Belpaire firebox.
| Principal Dimensions by Steve Llanso of Middle Run Media | |
|---|---|
| Class | O |
| Locobase ID | 10180 |
| Railroad | Bengal North |
| Country | India |
| Whyte | 4-4-0 |
| Number in Class | 297 |
| Road Numbers | |
| Gauge | Metre |
| Number Built | 297 |
| Builder | several |
| Year | 1900 |
| Valve Gear | Stephenson |
| Locomotive Length and Weight | |
| Driver Wheelbase (ft / m) | 6 / 1.83 |
| Engine Wheelbase (ft / m) | 12.17 / 3.71 |
| Ratio of driving wheelbase to overall engine wheelbase | 0.49 |
| Overall Wheelbase (engine & tender) (ft / m) | 39.37 / 12 |
| Axle Loading (Maximum Weight per Axle) (lbs / kg) | 18,256 / 8281 |
| Weight on Drivers (lbs / kg) | 36,428 / 16,523 |
| Engine Weight (lbs / kg) | 53,592 / 24,309 |
| Tender Loaded Weight (lbs / kg) | |
| Total Engine and Tender Weight (lbs / kg) | |
| Tender Water Capacity (gals / ML) | 1200 / 4.55 |
| Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT) | |
| Minimum weight of rail (calculated) (lb/yd / kg/m) | 30 / 15 |
| Geometry Relating to Tractive Effort | |
| Driver Diameter (in / mm) | 53 / 1346 |
| Boiler Pressure (psi / kPa) | 140 / 970 |
| High Pressure Cylinders (dia x stroke) (in / mm) | 14" x 20" / 356x508 |
| Tractive Effort (lbs / kg) | 8802 / 3992.52 |
| Factor of Adhesion (Weight on Drivers/Tractive Effort) | 4.14 |
| Heating Ability | |
| Tubes (number - dia) (in / mm) | 122 - 1.625" / 41 |
| Flues (number - dia) (in / mm) | |
| Flue/Tube length (ft / m) | |
| Firebox Area (sq ft / m2) | 56.50 / 5.25 |
| Grate Area (sq ft / m2) | 10.58 / 0.98 |
| Evaporative Heating Surface (sq ft / m2) | 753 / 69.98 |
| Superheating Surface (sq ft / m2) | |
| Combined Heating Surface (sq ft / m2) | 753 / 69.98 |
| Evaporative Heating Surface/Cylinder Volume | 211.32 |
| Computations Relating to Power Output (More Information) | |
| Robert LeMassena's Power Computation | 1481 |
| Same as above plus superheater percentage | 1481 |
| Same as above but substitute firebox area for grate area | 7910 |
| Power L1 | 3594 |
| Power MT | 435.02 |