Great Eastern class M15
London & North Eastern classes F4 and F5
Between 1884 and 1886, Worsdell had 40 tank locomotives built for the Great Eastern Railway for passenger service, which were called class M15. This first batch got Joy valve gear and due to their high consumption, they got the nickname “Gobblers”. Holden made 120 more between 1903 and 1909, which received Stephenson valve gear for lower fuel consumption. Many were fitted with a condensing gear for London traffic.
Between 1911 and 1920, 32 of the original batch were rebuilt to class M15R by adding a new boiler with a higher pressure and by installing Stephenson valve gear. At the LNER, the unrebuilt locomotives became the class F4 and the rebuilt ones became the F5. The first locomotives had already been withdrawn from 1913, but some F4s remained in service until 1956. In 1949, seven F5 were equipped with push-pull apparatus. The F5 was only withdrawn between 1955 and 1958.
Technical data
General
| Property | 1884 variant | 1903 variant | rebuilt M15R |
|---|---|---|---|
| Built | 1884-1886 | 1903-1909 | 1911-1920 |
| Manufacturers | Stratford | ||
| Wheel arrangement | 2-4-2T (Columbia) | ||
| Gauge | 1,435 mm (Standard gauge) | ||
Dimensions and weights
| Property | 1884 variant | 1903 variant | rebuilt M15R |
|---|---|---|---|
| Length | 10.62 m | ||
| Wheelbase | 7.01 m | ||
| Service mass | 52.7 t | 52.4 t | 54.8 t |
| Adhesion mass | 29.6 t | 27 t | |
| Rigid wheelbase | 7.01 m | ||
| Axle load | 15.9 t | 15.1 t | |
| Water capacity | 5,455 l | ||
| Fuel capacity | 2.3 t (coal) | ||
Boiler
| Property | 1884 variant | 1903 variant | rebuilt M15R |
|---|---|---|---|
| Grate area | 1.433 m² | 1.421 m² | |
| Firebox surface | 9.142 m² | 8.984 m² | |
| Tube heating surface | 88.778 m² | 96.118 m² | 94.575 m² |
| Evaporative heating surface | 97.92 m² | 105.259 m² | 103.559 m² |
| Total heating surface | 97.9 m² | 105.3 m² | 103.6 m² |
Power plant
| Property | 1884 variant | 1903 variant | rebuilt M15R |
|---|---|---|---|
| Driver diameter | 1,626 mm | ||
| Boiler pressure | 11 bar | 12.4 bar | |
| Expansion type | simple expansion | ||
| Cylinders | two, 444 x 610 mm | ||
Power
| Property | 1884 variant | 1903 variant | rebuilt M15R |
|---|---|---|---|
| Power source | steam | ||
| Estimated power | 317 kW (431 PS) | 373 kW (507 PS) | 391 kW (532 PS) |
| Starting effort | 69.5 kN | 78.2 kN | |
Calculated values
| Property | 1884 variant | 1903 variant | rebuilt M15R |
|---|---|---|---|
| Factor of adhesion | 1 : 4.18 | 1 : 3.81 | |
| Optimal speed | 27 km/h | 32 km/h | 31 km/h |
| Power-to-weight ratio | 6.0 kW/t | 7.1 kW/t | |
| Heating Surface Equivalent | 143.6 m² | 151.0 m² | 148.5 m² |
| Cylinder volume/HSE | 1 : 1,317.23 | 1 : 1,253.19 | 1 : 1,274.22 |
| Adhesive weight/Total | 1 : 1.78 | 1 : 1.94 | |
| Tractive force/Heating surface | 1 : 14.82 | 1 : 13.79 | 1 : 15.76 |
| Grate area/Heating surface | 1 : 68.33 | 1 : 74.07 | 1 : 72.88 |
| Firebox/Tube surface | 1 : 9.71 | 1 : 10.51 | 1 : 10.53 |
