A bucket wheel excavator is a piece of heavy machinery most commonly used for surface mining. This extremely large machine features a massive wheel outfitted with numerous buckets that scoop earth and dig into soil and other materials. These machines tend to be exceptionally large. A bucket wheel excavator usually features several tracks that propel it forward, as well as a tall conveyor belt that helps move waste materials. Many other components may be affixed to the excavator to make movement and transport of materials possible.
The wheel of the bucket wheel excavator can feature up to 20 or more buckets. These scoops can hold a significant amount of material, which means the bucket wheel excavator is a good choice for moving very large amounts of material very quickly. The buckets will dump the material into a specially designed boom that is often outfitted with a conveyor belt system. The belt will transfer the material to a sorting station, and the materials can be spread or sorted accordingly at this point in the machine.
One of the greatest advantages of the bucket wheel excavator is its ability to continuously move materials without stopping. The entire system is sometimes fully automated, which means human operation is not necessary; monitoring will still be necessary, of course, in case of an emergency, but the processes themselves can continue unabated without the need for human operation. The bucket can continue to spin and the materials can continue to be transported as long as the machine is powered.
These machines have been in use since the early 20th century, though the scale on which the bucket wheel excavator can now operate has grown exponentially. Original machines were fairly small and did not move as much material as they are capable of doing in modern times. The size of the bucket and the amount of power supplied to the machine will affect how much material can be transported continuously. The largest excavator, Bagger 293, is among the largest terrestrial vehicles in the world, and it can move 8.510 million cubic feet (240,000 cubic meters) of material in a day's operation. It is over 315 feet (95 meters) tall, making it one of the tallest operational vehicles on earth; operating the machine requires several operators and constant observation.