GWR 2600 Aberdare Class

The GWR 2600 Class Aberdare was a series of outside-cylinder 2-6-0 heavy goods locomotives designed by William Dean and introduced at Swindon Works in 1900, built specifically for the arduous coal traffic from the South Wales valleys to the coastal ports at Cardiff, Barry, Newport, and Swansea. The Welsh coal trade was the GWR's most commercially important freight business at the turn of the century, and the coal trains descending from the Rhondda, Merthyr, and Cynon valleys to the ports — heavily loaded, running on steeply graded lines with severe curves — demanded a locomotive type with more power and adhesion than the existing Dean Goods 0-6-0 could reliably provide on the heaviest trains.

The Aberdare — named after the South Wales town at the heart of the Cynon Valley coalfield it was designed to serve — used two outside cylinders and the 2-6-0 Mogul wheel arrangement, giving six coupled wheels for maximum adhesion on the coal trains and a leading pony truck for better guidance on the curved South Wales colliery lines. Dean's design was updated by Churchward after the latter succeeded Dean in 1902, with Churchward fitting his characteristic long-travel valve gear and eventually superheaters to the class, producing a significantly improved locomotive from Dean's original.

The Aberdares gave long and useful service on South Wales coal and goods traffic. Under Collett's superintendency they continued working the South Wales mineral lines, and several survived into British Railways ownership. None was preserved, though the class's commercial significance to the GWR — the South Wales coal traffic was the financial foundation of much of the GWR's Victorian prosperity — was substantial.