The reference for locomotives and railcars


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Great Western Railway Caesar class
originally Pyracmon, Ariadne and Caliph classes
Great Britain | 1847 | 117 produced
“Liffey” from the Ariadne class
“Liffey” from the Ariadne class
Locomotive Magazine, December 1913

Today, more than 100 GWR broad gauge freight locomotives, which originally belonged to different classes, are called the Caesar class. They all had the 0-6-0 wheel arrangement and were designed by Daniel Gooch and built in Swindon. In contrast to their predecessors, they did not have a haystack firebox, but one with a round top.

Using the possibilities of the broad gauge, they were significantly more powerful than other locomotives with this wheel arrangement. Due to the gentle curves of the broad-gauge tracks, the wheelbase could be made very long in order to obtain sufficient running smoothness despite the lack of carrying axles. At five feet in diameter, the wheels were smaller than the boiler diameter.

Schematic drawing of “Cato”
Schematic drawing of “Cato”
Locomotive Magazine, April 1902

The actual Caesar class consisted of eight saddle tank locomotives built in 1851 and 1852. Their service life ended between 1871 and 1880. A restructuring of the class names in 1865 resulted in the Pyracmon, Ariadne and Caliph class tender locomotives being included in the Caesar class.

The seven Pyracmon class locomotives were based on the Premier class, which were the first locomotives built in Swindon and were to be phased out between 1871 and 1873. The Ariadne and Caliph classes were also referred to as “Gooch Standard Goods” and were delivered in seven lots between 1852 and 1863.

Most locomotives were named after gods or well-known figures from ancient Greece, but some were named after British rivers or given other names altogether. This resulted in 102 locomotives that were retired between 1871 and 1883. An exception was the “Europa”, which was extensively rebuilt in 1869 and remained in service until 1892, when traffic on the broad gauge was discontinued.

VariantCaesarPyracmonAriadne, Caliph
Axle config0-6-0ST (Six-coupled) 0-6-0 (Six-coupled) 
Gauge7 ft 0 1/4 in (GWR broad gauge)
Dimensions and Weights
Wheelbase15 ft 4 in16 ft 2 1/2 in
Fixed wheelbase15 ft 4 in16 ft 2 1/2 in
Service weight72,688 lbs63,056 lbs69,720 lbs
Adhesive weight72,688 lbs63,056 lbs69,720 lbs
Axle load26,320 lbs22,736 lbs27,328 lbs
Fuel capacitycoal
Power sourcesteam
Estimated power350 hp (261 kW)400 hp (298 kW)450 hp (336 kW)
Optimal speed18 mph25 mph24 mph
Starting effort12,412 lbf10,010 lbf11,791 lbf
Power Plant
Driver diameter57 in60 in
Boiler pressure120 psi115 psi120 psi
Expansion typesimple
Cylinderstwo, 17 x 24 intwo, 16 x 24 intwo, 17 x 24 in
Grate area17.3 sq ft18.4 sq ft19.2 sq ft
Firebox area107.7 sq ft121.3 sq ft129.8 sq ft
Tube heating area1,255.3 sq ft1,241.7 sq ft1,444.2 sq ft
Evaporative heating area1,363 sq ft1,574 sq ft
Total heating area1,363 sq ft1,574 sq ft
Calculated Values
steam locomotive
tank locomotive
Daniel Gooch
last changed: 04/2023

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