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Withdrawal started in the 1950s; the last to be withdrawn was Clun Castle at the end of 1965.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