The Stockton and Darlington Railway (S&DR) was a railway company that operated in north-east England from 1825 to 1863. The world's first public railway to use steam locomotives, its first line connected collieries near Shildon with Stockton-on-Tees and Darlington, and was officially opened on 27 September 1825. The movement of coal to ships rapidly became a lucrative business, and the line was soon extended to a new port and town at Middlesbrough. While coal waggons were hauled by steam locomotives from the start, passengers were carried later.

S&DR’s first locomotive was, of course, Locomotion No 1, designed by Robert Stephenson and the first locomotive to run on a public railway. Third to be built was Black Diamond, subject of Allan Smith’s 7.25” gauge model shown at a Bristol exhibition.

It was effectively a beam engine on wheels with vertical cylinders. It was one of the first locomotives to use coupling rods rather than chains to drive its 0-4-0 wheel arrangement. The wheels were 4 feet in diameter and cast iron. The engine frame was of timber and the whole thing weighed 6.5 tons.

The cylinders were vertical and 10 inches in diameter and with 24 inches stroke. The boiler was 4 feet in diameter and 10 feet long with a heating surface of 60 square feet. It could haul a load of 90 tons at a speed of 6 to 8 mph.

These locomotives are, of course, much modelled, including in 7.25” gauge by Henry Greenly. Atelier MB in Switzerland has drawings and castings for a 5” gauge version.



By Allan Smith

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