Mine Trolleys, known as Mine Carts in the US, are special types of wagons, they are used to carry and transport materials across the mines, mostly stone. Occasionally, some mine trolleys have been used at the quarries, and other work sites.
The mine trolleys first appeared in Blue Mountain Mystery, working at the Blue Mountain Quarry. In Tale of the Brave, wooden mine trolleys were used by the workmen to carry and transport china clay around the Clay Pits, they were also used to unload china clay into the trucks for engines like Bill and Ben, who then take them to Brendam Docks. In the 4-D attraction, Bubbling Boilers, several mine trolleys were seen inside the Ulfstead Mine, in which Thomas bumps into after having a brakes failure, the mine trolleys starting to roll down the line, chasing after Thomas, until Thomas finally managed to bump them right off the rails and into the muddy water underneath.