What is sans pareil locomotive?

The Sans Pareil locomotive was a steam locomotive built by Timothy Hackworth in 1804. It was one of the earliest successful locomotives in the world and was the first to use flanged wheels on rails. The locomotive was built for the Wylam Colliery, a coal mine in Northumberland, England.

Sans Pareil had a vertical boiler and a single horizontal cylinder, with a connecting rod driving the rear axle directly. It had four wheels, with the two outer wheels connected by a crank axle to provide traction. Sans Pareil was capable of hauling a load of 30 tons at a speed of 8 miles per hour and was considered a major improvement over the earlier locomotives built by Richard Trevithick. The name "Sans Pareil" means "without equal" in French, which was a reference to the locomotive's superior performance.

The Sans Pareil locomotive had a short lifespan and was retired from service in 1805, as it was no longer powerful enough to haul the increasing loads of coal from the Wylam Colliery. Today, a replica of the locomotive can be seen at the Locomotion Museum in Shildon, County Durham, England.