Featuring two exceptional machines, filmed at open-cast coalmines in Wyoming and Germany. Ursa Major, the largest Bucyrus-Erie 2570-WS walking dragline working in North America, is the star at Black Thunder mine. The Bucketwheel 288 used at Garzweiler is the world's largest terrestrial moving machine. Take a close look at both machines, and other aspects of the mine such as spreading, coal haulage by train and reclamation.