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British Rail Standard class 7MT “Britannia”
The first of the British Railways standard designs was a Pacific that was formally intended for mixed service. Categorized into power class 7MT, it got driving wheels of 6 feet and 2 inches (or 1,880 mm) to reach spee...
General
| Property | British Rail Standard class 7MT “Britannia” tender BR1 |
|---|---|
| Built | 1951-1954 |
| Manufacturers | Crewe |
| Wheel arrangement | 4-6-2 (Pacific) |
| Gauge | 1,435 mm (Standard gauge) |
Dimensions and weights
| Property | British Rail Standard class 7MT “Britannia” tender BR1 |
|---|---|
| Length | 20.96 m |
| Wheelbase | 10.90 m |
| Rigid wheelbase | 4.27 m |
| Service weight | 95.5 t |
| Adhesive weight | 62.5 t |
| Axle load | 20.6 t |
| Total weight | 145.4 t |
| Water capacity | 19,321 l |
| Fuel capacity | 7.1 t (coal) |
Boiler
| Property | British Rail Standard class 7MT “Britannia” tender BR1 |
|---|---|
| Grate area | 3.902 m² |
| Firebox surface | 19.51 m² |
| Tube heating surface | 229.935 m² |
| Evaporative heating surface | 249.445 m² |
| Superheater surface | 66.704 m² |
| Total heating surface | 316.1 m² |
Power plant
| Property | British Rail Standard class 7MT “Britannia” tender BR1 |
|---|---|
| Driver diameter | 1,880 mm |
| Boiler pressure | 17.2 bar |
| Expansion type | simple expansion |
| Cylinders | two, 508 x 711 mm |
Power
| Property | British Rail Standard class 7MT “Britannia” tender BR1 |
|---|---|
| Power source | steam |
| Estimated power | 2,013 kW (2,737 PS) |
| Starting effort | 143.1 kN |
Calculated values
| Property | British Rail Standard class 7MT “Britannia” tender BR1 |
|---|---|
| Factor of adhesion | 1 : 4.28 |
| Optimal speed | 87 km/h |
| Power-to-weight ratio | 21.1 kW/t |
| Heating Surface Equivalent | 480.4 m² |
| Cylinder volume/HSE | 1 : 600.11 |
| Adhesive weight/Total | 1 : 1.53 |
| Tractive force/Heating surface | 1 : 9.45 |
| Grate area/Heating surface | 1 : 81.02 |
| Firebox/Tube surface | 1 : 11.79 |
| Total/Superheater | 1 : 3.74 |
