The GWR 4073 Class or Castle class locomotives were a group of 4-6-0 steam locomotives of the Great Western Railway. They were originally designed by the railway's Chief Mechanical Engineer, Charles Collett, for working the company's express passenger trains.

History

A development of the earlier Star Class, one hundred and seventy-one (171) were built, over a 25 year span from August 1923 to August 1950. They were numbered 4073–4099; 5000–5099; 7000–7037.

Although most were built new, sixteen locos were rebuilt from older locomotives—fifteen Star Class locomotives; and the Great Western Railway's sole 4-6-2 locomotive, number 111 The Great Bear.

The Castle class was noted for superb performance on the Cheltenham Flyer during the 1930s: on 6 June 1932, pulled by 5006 Tregenna Castle, the train covered 77 miles (124 km) from Swindon to Paddington at an average speed of 81.68 miles per hour (131.45 km/h). This world record for steam traction was widely regarded as an astonishing feat.

In 1926, number 5000 Launceston Castle was loaned to the London, Midland and Scottish Railway where it ran trials between London to Carlisle. It was rumoured that LMS tried to persuade GWR to build a batch of Castles for use on the West Coast Main Line.

Withdrawal started in the 1950s; the last to be withdrawn was Clun Castle at the end of 1965.

Specifications

Cylinders: 4; 16 in (406 mm) diameter, 26 in (660 mm) stroke
Valve gear: inside cylinders – Walschaert's; outside cylinders – derived from inside cylinders via rocking bars.
Valves: piston valves
Boiler pressure: 225 lbf/in² (1.55 MPa)
Driving wheel diameter: 6 ft 8.5 in (2.04 m)
Tractive Effort: 31,625 lbf (140.675 kN)
Engine weight: 79 tons 17 cwt (81.1 Mg)
Tender weight: 46 tons 14 cwt (47.44 Mg)

List of locomotives

See List of GWR 4073 Class locomotives

Preservation

Eight Castles survive in preservation:

Number	Name	Current location	Current status
4073	Caerphilly Castle	Swindon Steam Railway Museum	on static display
4079	Pendennis Castle	Didcot Railway Centre	under overhaul
5029	Nunney Castle	Tyseley Locomotive Works	operational, main line certified
5043	Earl of Mount Edgcumbe (Banbury Castle)	Tyseley Locomotive Works	under overhaul
5051	Earl Bathurst (Drysllwyn Castle)	Didcot Railway Centre	on static display
5080	Defiant (Ogmore Castle)	Buckinghamshire Railway Centre	on static display
7027	Thornbury Castle	The Railway Age Crewe	stored awaiting restoration
7029	Clun Castle	Tyseley Locomotive Works	on static display awaiting overhaul

References

• Brian Haresnape (1978). Collett & Hawksworth Locomotives—A Pictorial History. Ian Allan Ltd.

External links

• Daniel, John 4073 'Castle' class introduction. Great Western steam locomotives. .