Trevethick's Locomotive, 1803.
TrevithickÕs Coalbrookdale Engine, 1803
This engine was built by Richard Trevithick, a Cornish miner, in consequence of a wager of 1000 guineas that he would convey a load of iron a distance of 9 miles into Merthyr Tydvil, South Wales, upon a cast iron tramroad by the power of steam alone. The engine was finished in 1804 and succeeded in accomplishing the feat of drawing after it several wagons containing 10 tons of iron bar at the rate of 5 miles an hour, but it was ill constructed machine and having got out of order it was deserted by its builder. The boiler was cylindrical in form, flat at the ends and made of cast iron; the furnace and flues were inside the boiler in which a single cylinder of 8" dia. and 54" stroke was immersed. In this engine was first employed the "force draught" created by the steam, for working without a high stack, the exhaust system being turned into the stack about a foot above its junction with the boiler.
The Coalbrookdale engine drawing is a museum drawing based on an original contemporary sketch – the drawing is published in Wescott. It would appear from the following description that this engine is similar to, but not identical to, the Penydarran engine described above. A Single horizontal cylinder, 4.75 in. by 36 in., enclosed in a cast-iron return-flue boiler and provided with a flywheel, drove the wheels on one side only through spur gears. Steam was distributed through plug valves worked by tappets. Cylinder placed at same end of boiler as furnace door. Boiler pressure c. 50 lb. per sq. in. Cast-iron plate rails. Axles mounted directly on boiler, without a separate frame. No flanges on wheels.
A detailed account of TrevithickÕs work with this engine is given in the work Life of Trevithick by Francis Trevithick.
A brief account of Trevithick's engine is given in A History Of The Growth Of The Steam-Engine by Robert H. Thurston.
Another brief account is given in William H. BrownÕs The History of the First Locomotives In America