A variety of bucket-wheel excavator sizes can be found in Germany. The heavy equipment used in large-scale open pit mining operations and civil engineering are constructed here in different sizes in order to suit almost every possible condition. Bucket-wheel excavators (BWEs) in the United States are made smaller compared to the German models.
German industrial conglomerate ThyssenKrupp AG, through ThyssenKrupp Robbins, continues to make both large and compact BWEs available. Custom-built excavator sizes vary greatly to be able to reach a specific capacity. The standard design compact excavators operate at 5,230 cubic yards per day, while BWEs capable of handling as much as 32,390 cubic yards per day have to be custom-built systems. All compact BWEs consist of two-crawler travel mechanisms with stubby ballast booms designed as a backward extension of the turntable. Hydraulic cylinders support the bucket-wheel boom. The custom-built BWEs have contributed to production rates reaching 240,000 cubic meters per day. These specially designed machines can dig heights of as much as 100 meters and service weights of 13,500 tonnes.
Another German company, MAN Takraf, has contributed to the large excavator sizes. Its RB293 is used for open-cast coal mining in the German state of North Rhine Westphalia. The 14,196 metric ton (31.3 million pounds) BWE took three weeks to complete the 22 kilometer (14 mile) trip covering Autobahn 61, the Erft, a railroad line and several roads to the Garzweiler mine. The RB293 stretches to 220 meters (722 feet) and reaches 94.5 m. (310 ft.) at its highest point. The continuous digging machine with a maximum speed of less than one kilometer an hour can move 240,000 m. (8.475 million ft.) of earth daily. Modified bucket-wheel excavator sizes for the RB293 have reached lengths of 225 meters (738.2 feet) and heights of 96 meters (314.9 feet). The BWE, including its more than 70 feet in diameter bucket-wheel of as many as 20 buckets, can weigh as heavy as 14,200 tons (31.3 million pounds). Each bucket can hold over 15 cubic meters of material.
Sweden’s Sandvik Mining and Construction of the Sandvik Group, on the other hand, has focused least on developing a variety of excavator sizes. Research and development investments on improving mine automation systems have improved the safety levels and monitoring efficiency of the entire mining cycle. The largest of the Sandvik bucket-wheel excavator sizes is the PE100-1500/1.5×24.4. The custom-built and made-to-order mining vehicle has a nominal capacity of 7100 cubic meters (9290 cubic yards) per hour. The BWE has a block height of 24.5 meters (80 feet) and a bucket wheel boom reaching 27.8 m. (91 feet).
Bucket-wheel excavators can be considered as the largest digging machine. Complete automation of these heavy machines is expected to reduce the human error factor in mining operations.