Data from E L Ahrons, The British Steam Locomotive from 1825 to 1925 (London: Ian Allan, 1926); and from "Locomotives of the North London Railway," The Locomotive Magazine, Vol VIII (27 June 1903), p. 450.
Outside-cylindered tanks with single slide bars and cast iron wheels that used the same boiler as the bogie tanks that went into service 14 years earlier (Locobase 3502) . Unusually, the inside slide valves were arranged vertically and opened by valve rods that wrapped like horseshoes around the front axle. Production stretched over 5 years.
Additional data from 1907 Catalogue of Mechanical Engineering Collection in the Science Division of the Victoria & Albert Museum (Board of Education South Kensington), p 97, resulted in adopting 957 sq ft for the heating surface rather than Ahrons' 987 sq ft.
| Principal Dimensions by Steve Llanso of Middle Run Media | |
|---|---|
| Class | 15 |
| Locobase ID | 3649 |
| Railroad | North London |
| Country | Great Britain |
| Whyte | 0-6-0T |
| Number in Class | 26 |
| Road Numbers | |
| Gauge | Std |
| Number Built | 26 |
| Builder | Bow Works |
| Year | 1879 |
| Valve Gear | Stephenson |
| Locomotive Length and Weight | |
| Driver Wheelbase (ft / m) | 11.33 / 3.45 |
| Engine Wheelbase (ft / m) | 11.33 / 3.45 |
| Ratio of driving wheelbase to overall engine wheelbase | 1 |
| Overall Wheelbase (engine & tender) (ft / m) | 11.33 / 3.45 |
| Axle Loading (Maximum Weight per Axle) (lbs / kg) | 32,798 / 14,877 |
| Weight on Drivers (lbs / kg) | 98,392 / 44,630 |
| Engine Weight (lbs / kg) | 98,392 / 44,630 |
| Tender Loaded Weight (lbs / kg) | |
| Total Engine and Tender Weight (lbs / kg) | |
| Tender Water Capacity (gals / ML) | 956 / 3.62 |
| Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT) | 1.40 / 1 |
| Minimum weight of rail (calculated) (lb/yd / kg/m) | 55 / 27.50 |
| Geometry Relating to Tractive Effort | |
| Driver Diameter (in / mm) | 52 / 1321 |
| Boiler Pressure (psi / kPa) | 160 / 1100 |
| High Pressure Cylinders (dia x stroke) (in / mm) | 17" x 24" / 432x610 |
| Tractive Effort (lbs / kg) | 18,140 / 8228.18 |
| Factor of Adhesion (Weight on Drivers/Tractive Effort) | 5.42 |
| Heating Ability | |
| Tubes (number - dia) (in / mm) | 192 - 1.75" / 44 |
| Flues (number - dia) (in / mm) | |
| Flue/Tube length (ft / m) | 10.08 / 3.07 |
| Firebox Area (sq ft / m2) | 81 / 7.53 |
| Grate Area (sq ft / m2) | 16.30 / 1.51 |
| Evaporative Heating Surface (sq ft / m2) | 957 / 88.94 |
| Superheating Surface (sq ft / m2) | |
| Combined Heating Surface (sq ft / m2) | 957 / 88.94 |
| Evaporative Heating Surface/Cylinder Volume | 151.78 |
| Computations Relating to Power Output (More Information) | |
| Robert LeMassena's Power Computation | 2608 |
| Same as above plus superheater percentage | 2608 |
| Same as above but substitute firebox area for grate area | 12,960 |
| Power L1 | 2995 |
| Power MT | 201.32 |