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The reference for locomotives and railcars

Great Western Railway class 3031 “Achilles” / “Dean Single”

Great Britain 1894 30 produced
No. 3046 “Lord of the Isles” Locomotive Magazine, January 1899

The class 3031 of the Great Western Railway, also known as the “Dean Single”, was created by rebuilding of 30 members of the class 3001, which had been built by William Dean in the 7 feet 1/4 inch broad gauge and were rebuilt to standard gauge a short time later. Since an increase in power through a wider boiler was impossible with the standard gauge due to the limited space between the large wheels, the boiler was extended to the front. After the leading axle derailed in the middle of the box tunnel due to the increased weight, it was replaced with a bogie, resulting in the class 3031. Since the cylinders were located below the smoke box in class 3001, a special bogie had to be constructed. This could be pulled out after loosening four screws and slightly lifting the front part of the locomotive to ensure uncomplicated maintenance of the smoke box and cylinders.

First, two class 3001 locomotives were rebuilt in March 1894, the remaining 28 were rebuilt between June and December of the same year. A total of 50 more were factory built between 1894 and 1899. In service, the class 3031, like other locomotives with a 4-2-2 wheel arrangement, excelled with high sustained speeds. On May 9, 1904, a mail train was able to travel the 117 miles from Bristol to London-Paddington in just under 100 minutes for the first time, which corresponds to an average speed of around 70 mph. However, since one driving axle was soon no longer sufficient, they were withdrawn between 1908 and 1915. Today there is a replica of No. 3041 “The Queen”, which was completed in 1982.

No. 3050 “Royal Sovereign” J.R. Howden, The Boys' Book of Locomotives

Technical data

General

Built
1894-1899
Manufacturers
Swindon
Wheel arrangement
4-2-2 (Single)
Gauge
1,435 mm (Standard gauge)

Dimensions and weights

Wheelbase
7.16 m
Service mass
49.8 t
Adhesion mass
18.3 t
Total mass
82.8 t
Rigid wheelbase
2.74 m
Axle load
18.3 t
Water capacity
16,364 l

Boiler

Grate area
1.932 m²
Firebox surface
11.799 m²
Tube heating surface
133.223 m²
Evaporative heating surface
145.022 m²
Total heating surface
145.0 m²

Power plant

Driver diameter
2,350 mm
Boiler pressure
11 bar
Expansion type
simple expansion
Cylinders
two, 483 x 610 mm

Power

Power source
steam
Estimated power
541 kW (736 PS)
Starting effort
56.7 kN

Calculated values

Factor of adhesion
1 : 3.17
Optimal speed
58 km/h
Power-to-weight ratio
10.9 kW/t
Heating Surface Equivalent
204.0 m²
Cylinder volume/HSE
1 : 1,093.13
Adhesive weight/Total
1 : 2.72
Tractive force/Heating surface
1 : 8.16
Grate area/Heating surface
1 : 75.06
Firebox/Tube surface
1 : 11.29
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