Data from J F Gairns, "Locomotives for Special Service on British Railways", Engineering Magazine, Volume 26, No 5 (Februay 1904), p. 711; and "L&YR Class 21" in Wikipedia at [], last accessed 8 June 2024
. Horwich's serial numbers ran 811-820, 921-930, and 1092-1011.
These four-coupled saddle-tanks shunted (switched) trains on the most tightly curved sidings within the L&Y's marshalling yards. Vulcan supplied three to start the class in 1886, but Locobase's data describes J A F Aspinall's modifications. These included raising the boiler pressure by 20 psi (1.38 bar ).
According to Wikipedia, "Pugs were allocated by the L&YR for operation in the industrial areas and docks of Fleetwood, Goole, Liverpool and Salford. In later times they became more widely dispersed, reaching places such as Bristol, Bangor, Crewe, Derby, Widnes, York and Swansea."
Clearly the Pugs filled a niche as indicated by the 23 engines taken into British Railways in 1948. BR retired its first Pug in 1956 and its last in 1964.
| Principal Dimensions by Steve Llanso of Middle Run Media | |
|---|---|
| Class | Class 21 Pug / 0F |
| Locobase ID | 12252 |
| Railroad | Lancashire & Yorkshire |
| Country | Great Britain |
| Whyte | 0-4-0ST |
| Number in Class | 57 |
| Road Numbers | 11200-11257 |
| Gauge | Std |
| Number Built | 57 |
| Builder | Horwich |
| Year | 1891 |
| Valve Gear | Stephenson |
| Locomotive Length and Weight | |
| Driver Wheelbase (ft / m) | 5.75 / 1.75 |
| Engine Wheelbase (ft / m) | 5.75 / 1.75 |
| Ratio of driving wheelbase to overall engine wheelbase | 1 |
| Overall Wheelbase (engine & tender) (ft / m) | 5.75 / 1.75 |
| Axle Loading (Maximum Weight per Axle) (lbs / kg) | |
| Weight on Drivers (lbs / kg) | 47,600 / 21,591 |
| Engine Weight (lbs / kg) | 47,600 / 21,591 |
| Tender Loaded Weight (lbs / kg) | |
| Total Engine and Tender Weight (lbs / kg) | |
| Tender Water Capacity (gals / ML) | 540 / 2.05 |
| Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT) | 0.80 / 0.70 |
| Minimum weight of rail (calculated) (lb/yd / kg/m) | 40 / 20 |
| Geometry Relating to Tractive Effort | |
| Driver Diameter (in / mm) | 36 / 925 |
| Boiler Pressure (psi / kPa) | 160 / 1100 |
| High Pressure Cylinders (dia x stroke) (in / mm) | 13" x 18" / 330x457 |
| Tractive Effort (lbs / kg) | 11,492 / 5212.69 |
| Factor of Adhesion (Weight on Drivers/Tractive Effort) | 4.14 |
| Heating Ability | |
| Tubes (number - dia) (in / mm) | 104 - 1.75" / 44 |
| Flues (number - dia) (in / mm) | |
| Flue/Tube length (ft / m) | 8.25 / 2.51 |
| Firebox Area (sq ft / m2) | 43 / 3.99 |
| Grate Area (sq ft / m2) | 7.20 / 0.67 |
| Evaporative Heating Surface (sq ft / m2) | 476 / 44.22 |
| Superheating Surface (sq ft / m2) | |
| Combined Heating Surface (sq ft / m2) | 476 / 44.22 |
| Evaporative Heating Surface/Cylinder Volume | 172.14 |
| Computations Relating to Power Output (More Information) | |
| Robert LeMassena's Power Computation | 1152 |
| Same as above plus superheater percentage | 1152 |
| Same as above but substitute firebox area for grate area | 6880 |
| Power L1 | 2399 |
| Power MT | 222.22 |