Which locomotive, built by Richard Trevithick, made the first successful run hauling a load on rails in 1804?

Richard Trevithick’s Penydarren locomotive made the first successful run hauling a load on rails in 1804.

Built at the Penydarren Ironworks in Wales, the experimental engine ran on the Merthyr Tramroad, a plateway connecting ironworks with the Glamorganshire Canal. On February 21, 1804, it hauled a train carrying about 10 tons of iron, demonstrating that steam power could move a loaded railway train.

The locomotive was a pioneering high-pressure design, but its heavy weight damaged the fragile cast-iron plate rails. Later trials reportedly involved loads as great as 25 tons, yet the experiment did not lead to continuous locomotive operation on that line. Horses remained important until later railway improvements.

The name can appear as “Penydarren,” “Pen-y-Darren,” or “Penydarren locomotive.” It is sometimes confused with Puffing Billy, which was an early colliery locomotive in England, or Rocket, which became famous decades later after the Rainhill Trials of 1829.