The reference for locomotives and railcars
Great Western Railway Iron Duke and Rover class
Great Britain | 1846 | 49 produced
Replica of the Iron Duke at the National Railway Museum, York
Replica of the Iron Duke at the National Railway Museum, York
David Ingham

Based on the success of the Firefly class, Daniel Gooch wanted to build an even more powerful and faster express locomotive. The driving wheels were increased from seven to eight feet and the largest possible boiler was installed in order to be able to take full advantage of the broad gauge. The wheel arrangement was still 2-2-2 and all wheels were mounted between the inner and outer frames. The cylinders were mounted between the inner frames.

“Great Western” in its original condition
“Great Western” in its original condition
Die Lokomotive, September 1937

The “Great Western” was completed in 1846 as the forerunner of the series. After just a short trial, the leading axle broke, which was attributed to the fact that the locomotive was too heavy to distribute the load over just three axles. The solution was to replace the leading axle with two axles that were also mounted in the frame. Although this made the locomotive heavier overall, the load on the driving axle fell. A further 29 series pieces were built in this form. The class was named “Iron Duke” after the first newly built machine and is said to have reached a top speed of 78 mph. The five-car express between London and Bristol is said to have averaged 68 mph on the 53 miles long section to Didcot.

“Great Western” with fixed leading axles
“Great Western” with fixed leading axles
Die Lokomotive, September 1937

In 1871 the “Great Britain”, “Prometheus” and “Estaffete” locomotives were converted to the Rover class. They received a larger boiler with higher pressure and a flat, elevated firebox instead of the previous haystack-shaped firebox. While the Iron Duke class locomotives were gradually phased out, their names were reused for 19 newly built Rover class examples, produced up to 1888.

The last engines of the Rover class did not have long lives, as broad gauge operations ceased in 1892. All pieces were then scrapped. It was not until 1985 that a working replica of the Iron Duke was built using parts from two Hunslet Austerity tank locos. It was not restored to service after her boiler life expired and now stands at the Didcot Railway Centre.

VariantGreat WesternIron DukeRover
Axle config2-2-2 (Jenny Lind) 4-2-2 (Single) 
Gauge7 ft 0 1/4 in (GWR broad gauge)
Dimensions and Weights
Wheelbase16 ft18 ft 8 in18 ft
Fixed wheelbase16 ft18 ft 8 in18 ft
Service weight64,961 lbs85,568 lbs93,408 lbs
Adhesive weight33,598 lbs31,802 lbs36,839 lbs
Total weight98,562 lbs
Axle load33,598 lbs31,802 lbs36,839 lbs
Water capacity4,323 us gal2,162 us gal3,603 us gal
Fuel capacitycoal
Power sourcesteam
Estimated power300 hp (224 kW)400 hp (298 kW)600 hp (447 kW)
Optimal speed28 mph31 mph40 mph
Top speed80 mph
Starting effort6,885 lbf8,262 lbf9,639 lbf
Power Plant
Driver diameter96 in
Boiler pressure100 psi120 psi140 psi
Expansion typesimple
Cylinderstwo, 18 x 24 in
Grate area22.6 sq ft25.5 sq ft24 sq ft
Firebox area151 sq ft131.8 sq ft137 sq ft
Tube heating area1,474 sq ft1,596.2 sq ft1,948 sq ft
Evaporative heating area1,625 sq ft1,728 sq ft2,085 sq ft
Total heating area1,625 sq ft1,728 sq ft2,085 sq ft
Calculated Values
steam locomotive
Daniel Gooch
last changed: 07/2022

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