Bucket-wheel excavators are heavy equipment used in surface mining and civil engineering. They are among the largest vehicles ever constructed. The excavation component itself is a large rotating wheel mounted on an arm or boom. On the outer edge of the wheel is a series of scoops or buckets. As the wheel turns, the buckets remove soil or rock from the target area and carry it around to the backside of the wheel, where it falls onto a conveyor, which carries it up the arm toward the main body of the excavator.
These tremendous earth-movers take 5 years to assemble, require 5 people to operate, weigh more than 13,000 short tons (12,000 t), and have a daily capacity of 240,000 short tons (220,000 t) of brown coal.
On this pictures you can see when it crawled from one mine to the other - across 22 kilometers of fields, roads, railway crossings, villages and countryside... As it could not go around the obstacles, it headed in a straight line, so the workers prepared the way by piling up sand cushions on top of highways and train tracks, removing power-lines and seeding the fields with special grass to make its progress smoother.