North Eastern class R
London & North Eastern class D20
Great Britain 1899 60 produced
Developed by Wilson Worsdell, the Class R was a 4-4-0 with larger dimensions than had previously been the norm for this wheel arrangement in Britain. From 1899 30 were built and another 30 in 1906 and 1907. During World War I they were rebuilt with a superheater. At the LNER they became the D20. After some received new piston valves in 1936, the rebuilt ones became the D20/2 class and the remainder the D20/1. The British Railways received 49 of the original 60 locomotives, these disappeared by 1957.
Technical data
General
| Property | as built | superheated |
|---|---|---|
| Built | 1899-1907 | 1915 |
| Manufacturers | Gateshead | |
| Wheel arrangement | 4-4-0 (American) | |
| Gauge | 1,435 mm (Standard gauge) | |
Dimensions and weights
| Property | as built | superheated |
|---|---|---|
| Wheelbase | 7.24 m | |
| Total wheelbase | 14.10 m | |
| Service mass | 52.5 t | |
| Adhesion mass | 35.8 t | |
| Total mass | 91 t | |
| Rigid wheelbase | 2.90 m | |
| Axle load | 20 t | 20.1 t |
| Water capacity | 16,080 l | |
| Fuel capacity | 5.1 t (coal) | |
Boiler
| Property | as built | superheated |
|---|---|---|
| Grate area | 1.858 m² | |
| Firebox surface | 13.378 m² | 12.914 m² |
| Tube heating surface | 128.485 m² | 91.138 m² |
| Evaporative heating surface | 141.863 m² | 104.052 m² |
| Total heating surface | 141.9 m² | 123.0 m² |
| Superheater surface | 18.952 m² | |
Power plant
| Property | as built | superheated |
|---|---|---|
| Driver diameter | 2,083 mm | |
| Boiler pressure | 13.8 bar | |
| Expansion type | simple expansion | |
| Cylinders | two, 483 x 660 mm | |
Power
| Property | as built | superheated |
|---|---|---|
| Power source | steam | |
| Estimated power | 615 kW (836 PS) | 764 kW (1,039 PS) |
| Starting effort | 86.6 kN | |
Calculated values
| Property | as built | superheated |
|---|---|---|
| Factor of adhesion | 1 : 4.06 | |
| Optimal speed | 43 km/h | 55 km/h |
| Power-to-weight ratio | 11.7 kW/t | 14.5 kW/t |
| Heating Surface Equivalent | 208.8 m² | 206.5 m² |
| Cylinder volume/HSE | 1 : 1,157.36 | 1 : 1,169.84 |
| Adhesive weight/Total | 1 : 1.47 | |
| Tractive force/Heating surface | 1 : 12.74 | 1 : 14.70 |
| Grate area/Heating surface | 1 : 76.35 | 1 : 66.20 |
| Firebox/Tube surface | 1 : 9.60 | 1 : 7.06 |
| Total/Superheater | 1 : 5.49 | |
