London & South Western class 415 “Radial Tanks”
For the suburban lines in London, William Adams provided his class 46, which had outside cylinders, with an additional trailing axle in order to be able to accommodate larger coal supplies. Since this axle was in a radial axle box, the locomotive was nicknamed the “Radial Tank”. Four manufacturers delivered a total of 71 locomotives, the last of which had a boiler pressure of 160 instead of 140 psi. As early as 1895, the locomotives were replaced by other locomotives in their original area of operation, after which they were relocated to branch lines in rural areas. After the first were retired in 1916, the largest number only disappeared between 1923 and 1928 under the Southern Railway. Three locomotives even survived on the Lyme Regis branch until 1961, because initially no other suitable locomotives were found for the tight curves. One of these today belongs to the Bluebell Railway but is not operational.
Technical data
General
| Property | first batches | last batches |
|---|---|---|
| Built | 1882-1885 | |
| Manufacturers | Robert Stephenson & Co., Dübs & Co., Neilson & Co., Beyer, Peacock & Co. | |
| Wheel arrangement | 4-4-2T (Atlantic) | |
| Gauge | 1,435 mm (Standard gauge) | |
Dimensions and weights
| Property | first batches | last batches |
|---|---|---|
| Length | 11.11 m | |
| Wheelbase | 8.97 m | |
| Service mass | 57 t | |
| Adhesion mass | 31.5 t | |
| Rigid wheelbase | 2.59 m | |
| Axle load | 15.7 t | |
| Water capacity | 5,455 l | |
| Fuel capacity | 1 t (coal) | |
Boiler
| Property | first batches | last batches |
|---|---|---|
| Grate area | 1.682 m² | |
| Firebox surface | 10.312 m² | |
| Tube heating surface | 87.793 m² | |
| Evaporative heating surface | 98.106 m² | |
| Total heating surface | 98.1 m² | |
Power plant
| Property | first batches | last batches |
|---|---|---|
| Driver diameter | 1,702 mm | |
| Boiler pressure | 9.7 bar | 11 bar |
| Expansion type | simple expansion | |
| Cylinders | two, 444 x 610 mm | |
Power
| Property | first batches | last batches |
|---|---|---|
| Power source | steam | |
| Estimated power | 391 kW (532 PS) | 418 kW (568 PS) |
| Starting effort | 58.1 kN | 66.4 kN |
Calculated values
| Property | first batches | last batches |
|---|---|---|
| Factor of adhesion | 1 : 5.32 | 1 : 4.66 |
| Optimal speed | 42 km/h | 39 km/h |
| Power-to-weight ratio | 6.9 kW/t | 7.3 kW/t |
| Heating Surface Equivalent | 149.7 m² | |
| Cylinder volume/HSE | 1 : 1,264.12 | |
| Adhesive weight/Total | 1 : 1.81 | |
| Tractive force/Heating surface | 1 : 12.36 | 1 : 14.13 |
| Grate area/Heating surface | 1 : 58.33 | |
| Firebox/Tube surface | 1 : 8.51 | |