|Power Classification||4MT reclassified 3MT in 1953|
|Introduced||1927 – 1929|
|Designer||Churchward , Collett|
|Driving Wheels||4ft 7.5ins|
|Boiler Pressure||200psi superheated|
|Cylinders||Outside – 17in x 24in|
|Valve Gear||Stephenson (piston valve)|
These engines (4575–4599 and 5500–5574) were developed from the 4500 class with larger side tanks which had sloping tops to increase water capacity.
The class worked extensively in Wales and the West of England. One of the star turns of the class was hauling part of the Cambrian Coast Express to Pwllheli in the 1950s and 1960s, as well as parts of the Cornish Riviera Express. Despite their apparently small size, they were capable of good acceleration, and could haul passenger trains of up to 11 coaches.
A number were fitted with auto apparatus in 1953 to enable them to run push-pull trains on South Wales lines with auto trailers.
No. in Service
The first withdrawal of the 4575 class was 4586 in 1956 whilst the last eleven remained in service until 1964. Of the eleven withdrawn in 1964 six were based at Southall, two each at Yeovil Town and Gloucester and one at Taunton. No fewer than 11 of these tank engines survived.