London & North Western Prince of Wales Tank class and class 2665 or “5ft 6in Tank (Superheated)”
London, Midland & Scottish class 4P
The Prince of Wales Tanks were 47 4-6-2T tank locomotives which Charles Bowen Cooke had built in Crewe between 1910 and 1916 for the LNWR. As their name suggests, they were referred to as tank versions of the Prince of Wales Class. However, they were more closely related to the Precursor Tanks, which had one less driving axle. They were also known as class 2665 after their running numbers and also as “5ft 6in Tank (Superheated)”.
Twelve locomotives were built without superheaters, but were rebuilt after a short time. The area of operation included, among others, suburban trains from London-Euston. Since the axle load was lower than that of the Precursor Tanks, they could be used more freely. This was the case, for example, on a 120-mile route in Wales. They all came to the LMS in 1923 and were decommissioned there between 1935 and 1941. Their successors were the 2-6-4T tank locomotives designed by Fowler and Stanier.
Technical data
General
| Property | saturated | superheated |
|---|---|---|
| Built | 1910-1916 | |
| Manufacturers | Crewe | |
| Wheel arrangement | 4-6-2T (Pacific) | |
| Gauge | 1,435 mm (Standard gauge) | |
Dimensions and weights
| Property | saturated | superheated |
|---|---|---|
| Wheelbase | 10.29 m | |
| Service mass | 79.3 t | 78.2 t |
| Adhesion mass | 45.2 t | 44.7 t |
| Rigid wheelbase | 4.27 m | |
| Axle load | 16.8 t | |
| Water capacity | 7,730 l | |
| Fuel capacity | 3 t (coal) | |
Boiler
| Property | saturated | superheated |
|---|---|---|
| Grate area | 2.22 m² | |
| Firebox surface | 12.728 m² | 12.821 m² |
| Tube heating surface | 124.304 m² | 110.741 m² |
| Evaporative heating surface | 137.032 m² | 123.561 m² |
| Total heating surface | 137.0 m² | 146.6 m² |
| Superheater surface | 23.04 m² | |
Power plant
| Property | saturated | superheated |
|---|---|---|
| Driver diameter | 1,740 mm | |
| Boiler pressure | 12.1 bar | |
| Expansion type | simple expansion | |
| Cylinders | two, 470 x 660 mm | two, 508 x 660 mm |
Power
| Property | saturated | superheated |
|---|---|---|
| Power source | steam | |
| Estimated power | 559 kW (760 PS) | 783 kW (1,065 PS) |
| Starting effort | 86.0 kN | 100.5 kN |
Calculated values
| Property | saturated | superheated |
|---|---|---|
| Factor of adhesion | 1 : 5.16 | 1 : 4.37 |
| Optimal speed | 40 km/h | 48 km/h |
| Power-to-weight ratio | 7.1 kW/t | 10.0 kW/t |
| Heating Surface Equivalent | 200.7 m² | 233.7 m² |
| Cylinder volume/HSE | 1 : 1,141.43 | 1 : 1,145.27 |
| Adhesive weight/Total | 1 : 1.75 | |
| Tractive force/Heating surface | 1 : 13.10 | 1 : 14.31 |
| Grate area/Heating surface | 1 : 61.73 | 1 : 66.04 |
| Firebox/Tube surface | 1 : 9.77 | 1 : 8.64 |
| Total/Superheater | 1 : 5.36 | |
