Holy Cow Tractor Pulling Team

Bucket-wheel excavator

Bucket-wheel excavators (BWEs) are heavy equipment used in surface mining and mechanical engineering/civil engineering. The primary function of BWEs is to act as a continuous digging machine in large-scale open pit mining operations. What sets BWEs apart from other large-scale mining equipment, such as bucket chain excavators, is their use of a large wheel consisting of a continuous pattern of buckets used to scoop material as the wheel turns. They are among the largest vehicles ever constructed, and the biggest bucket-wheel excavator ever built, Bagger 293, is the largest terrestrial (land) vehicle in human history according to the Guinness Book of World Records. Bucket-wheel excavators have been used in mining for the past century, with some of the first being manufactured in the 1920s.[1] They are used in conjunction with many other pieces of mining machinery (conveyer belts, spreaders, crushing stations, heap-leach systems, etc.) to move and mine massive amounts of overburden (waste). While the overall concepts that go into a BWE have not changed much, their size has grown drastically since the end of World War Two. In the 1950s two German mining firms ordered the world's first extremely large BWEs, and had three BWEs built for mining lignite near Cologne, Germany. The German BWEs had a wheel of over 52 feet (16 m) in diameter, weighed 5,500 short tons (5,000 t) and was over 600 feet (180 m) long, with eighteen crawler units for movement and could cut a swath of over 600 feet (180 m) feet at one time [2] BWEs built since the 1990s, such as the Bagger 293, have reached sizes as large as 96 metres (314.9 feet) tall, 225 metres (738.2 feet) long, and as heavy as 14,200 tons (31.3 million lb). The bucket-wheel itself can be over 70 feet in diameter with as many as 20 buckets, each of which can hold over 15 cubic metres of material. BWEs have also advanced with espect to the extreme conditions in which they are now capable of operating. Many BWEs have been designed to operate in climates with temperatures as low as -45C (-49F). Developers are now moving their focus toward automation and the use of electrical power.[3] A bucket wheel excavator (BWE) consists of a superstructure to which several more components are fixed. The bucket wheel from which the machines get their name is a large, round wheel with a configuration of scoops which is fixed to a boom and is capable of rotating. Material picked up by the cutting wheel is transferred back along the boom. In early cell-type bucket wheels, the material was transferred through a chute leading from each bucket, while newer cell-less and semi-cell designs use a stationary chute through which all of the buckets discharge.[4] A discharge boom receives material through the superstructure from the cutting boom and carries it away from the machine, frequently to an external conveyor system. A counterweight boom balances the cutting boom and is cantilevered either on the lower part of the superstructure (in the case of compact BWEs) or the upper part (in the case of mid-size C-frame BWEs). In the larger BWEs, all three booms are supported by cables running across towers at the top of the superstructure.[5] Beneath the superstructure lay the movement systems. On older models these would be rails for the machine to travel along, but newer BWEs are frequently equipped with crawlers, which grant them increased flexibility of motion. To allow it to complete its duties, the superstructure of a BWE is capable of rotating about a vertical axis (slewing). The cutting boom can be tilted up and down (hoisting). The speeds of these operations are on the orders of 30 m/min and 5 m/min, respectively. Slewing is driven by large gears, while hoisting generally makes use of a cable system.

C.O.W. Systems