Railway History Map of Britain - South West
Resource Type: Image | Posted on 14th November 2011 by Liam Physick
This extract from the Railway History Map of Britain shows the railways in the South West of England. Catch-me-who-can can be seen here, as well as the Pen-y-Darren locomotive, built by Trevithick in 1802 (not 1804, as the map says), six years before Catch-me-who-can. Trevithick built a high-pressure fixed steam engine to drive a hammer at the Pen-y-Darren Ironworks in Merthyr Tydfil: with the assistance of a Pen-y-Darren employee, Rees Jones, he converted the engine into a locomotive, and in 1803, sold the patents for his locomotives to Samuel Homfray, proprietor of the Ironworks. Homfray was so impressed by the locomotive that he bet Richard Crawshay, owner of the Cyfarthfa Iron Works, 500 guineas that it could pull 10 tons of iron along the Merthyr Tydfil Tramroad from Penydarren to Abercynon, over 9.75 miles. The run, which attracted great interest from the public, took place on 21st February 1804: the locomotive, just as Homfray had bet, carried 10 tons of iron, five wagons and 70 men in four hours and five minutes, at an average speed of 2.4 miles per hour (maximum speed five miles per hour). It was a milestone in locomotive design: the cylinder was moved so that the firedoor was safely away from the moving parts, the crankshaft was placed at the chimney end, the cylinder was coupled to a large flywheel mounted on one side, the rotational inertia (resistance to changes in rotation) of the flywheel evened out the movement, the movement was transferred to a central cog-wheel in turn connected to the driving wheels, the engine used a high-pressure cylinder without a condenser, and the exhaust steam was sent up the chimney thus assisting the draught through the fire, which made for greater efficiency by drawing the fire’s hot gases more powerfully through the boiler. It also had a rather unusual appearance: the one cylinder, which had very long stroke, was mounted partly in the boiler, and a piston rod crosshead ran along a sidebar, hence the trombone-like appearance. Soon after starting its journey, the locomotive’s chimney struck a small bridge, destroying both. Under the terms of the bet, Trevithick had to control and repair the locomotive unaided. He soon cleared the debris and repaired the chimney, and the engine completed its journey without further mishap. Homfray won his bet, but more significantly Trevithick had shown that, provided the gradient was not too severe (the steep gradient and sharp curves on the route meant the locomotive could not do the return journey), a steam locomotive could successfully haul carriages on a smooth iron road. Unfortunately, the locomotive was so heavy that it broke some of the short cast-iron plates of the Tramroad, which were designed only to support horse-drawn wagons: the road thus returned to horsepower once the trial run was complete. The Pen-y-Darren locomotive only made two more runs, breaking the rails each time, so Homfray decided to abandon the project feeling it would never reduce transport costs: it was placed on blocks and reverted to its previous function of driving hammers. In 1981, a full-size replica was built and delivered to Swansea Museum: it is now in the National Waterfront Museum and several times a year runs on a 40 m length of rail outside the Museum
Categorised under: Landmarks, Landscapes & Locomotives
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