BUCKET WHEEL EXCAVATOR

     Bucket-wheel excavators are heavy equipment used in surface mining and civil engineering. They are among the largest vehicles ever constructed, and the biggest bucket-wheel excavator ever built, Bagger 293, is the largest terrestrial vehicle in human history.

Operation
     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. Additional conveyors then may carry it further; in some cases, several long conveyors are placed end-to-end, each supported by a large vehicular base, usually with caterpillar tracks.

Size
     The largest bucket-wheel excavators in the world are used in German strip-mining operations. These tremendous earth-movers can cost over $500 cores, 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 or overburden.


It can remove over 76,455 cubic meters each day. (100,000 large dump trucks at 40yds. each).