London & North Western Precedent class
The LNWR Precedent class consisted of 70 2-4-0 express locomotives with a driver diameter of 6 ft 6 in or 1,981 mm, built between 1874 and 1882. As usual, they had inside cylinders with a common steam chest. Francis Webb designed them so well that they could reach more than 50 mph with a total train weight of 200 tons on trial runs. In service, they could haul ten carriages with a speed of 45 mph.
Between 1891 and 1901, 62 of the 70 locomotives were replaced by new locomotives of the “Improved Precedent” class which got the same numbers and names. The remaining eight were rebuilt into the same class, but retained the thinner frames and more parts. Of these rebuilt locomotives, four survived until the 1923 grouping and got the LMS numbers 5000 to 5003. They were withdrawn between 1929 and 1934.
Technical data
General
- Built
- 1874-1882
- Manufacturers
- Crewe
- Wheel arrangement
- 2-4-0 (Porter)
- Gauge
- 1,435 mm (Standard gauge)
Dimensions and weights
- Wheelbase
- 4.78 m
- Service mass
- 33.3 t
- Adhesion mass
- 22.6 t
- Total mass
- 58.7 t
- Rigid wheelbase
- 4.78 m
- Axle load
- 11.7 t
- Water capacity
- 8,184 l
- Fuel capacity
- 4.1 t (coal)
Boiler
- Grate area
- 1.589 m²
- Firebox surface
- 9.615 m²
- Tube heating surface
- 91.092 m²
- Evaporative heating surface
- 100.707 m²
- Total heating surface
- 100.7 m²
Power plant
- Driver diameter
- 2,007 mm
- Boiler pressure
- 9.7 bar
- Expansion type
- simple expansion
- Cylinders
- two, 432 x 610 mm
Power
- Power source
- steam
- Estimated power
- 298 kW (405 PS)
- Starting effort
- 46.5 kN
Calculated values
- Factor of adhesion
- 1 : 4.76
- Optimal speed
- 39 km/h
- Power-to-weight ratio
- 9.0 kW/t
- Heating Surface Equivalent
- 148.8 m²
- Cylinder volume/HSE
- 1 : 1,200.00
- Adhesive weight/Total
- 1 : 1.48
- Tractive force/Heating surface
- 1 : 9.64
- Grate area/Heating surface
- 1 : 63.38
- Firebox/Tube surface
- 1 : 9.47
