World’s Largest Machine
Bagger 293, previously known as the MAN TAKRAF RB293, is a giant bucket-wheel excavator made by the German industrial company TAKRAF, formerly an East German Kombinat. It owns or shares some records for terrestrial vehicle in the Guinness Book of Records. Bagger 293 was built in 1995, one of a group of similar sized ‘sibling’ vehicles such as the Bagger 281 (built in 1958), Bagger 285 (1975), Bagger 287 (1976), Bagger 288 (1978), Bagger 291 (1993), etc.
It is used in a brown coal mine near Hambach in Germany. It is called Bagger 293 by its current owner, RWE Power AG (the second-largest energy producer of Germany). It was called RB293 by its former owner, the brown coal company Rheinbraun, which since 1932 was already a daughter company of RWE (but during an internal reshuffle in 2003 merged with another daughter company to form RWE Power AG). Manufacturer TAKRAF generally refers to it as an excavator of the type SRs 8000.
Bagger 293 is 95 metres (314.9 feet) tall (highest terrestrial vehicle, size shared with Bagger 288). It is 225 metres (738.2 feet) long (same as Bagger 287), weighs 14,200 tons (31.3 million lb), and requires five people to operate. The bucket-wheel itself is over 70 feet (over 21.3 metres) in diameter with 20 buckets, each of which can hold over 15 cubic metres of material.
It can move 240,000 cubic metres (8.510 million cubic feet) of earth per day (the same as Bagger 288).
Bagger 288 (Excavator 288), built by the German company Krupp for the energy and mining firm Rheinbraun, is a bucket-wheel excavator or mobile strip mining machine. When its construction was completed in 1978, Bagger 288 superseded NASA’s Crawler-Transporter, used to carry the Space Shuttle and Apollo Saturn V launch vehicle, as the largest land vehicle in the world at 13,500 tons.
The Bagger 288 was built for the job of removing overburden prior to coal mining in Tagebau Hambach (stripmine Hambach), Germany. It can excavate 240,000 tons of coal or 240,000 cubic metres of overburden daily – the equivalent of a football field (soccer) dug to 30 m (98 ft) deep. The coal produced in one day fills 2400 coal wagons. The excavator is up to 220 m (721 ft) long and approximately 96 m (315 ft) high. The Bagger’s operation requires 16.56 megawatts of externally supplied electricity. It can travel 2 to 10 m (6.6 to 33 ft) per minute (0.1 to 0.6 km/h). The chassis of the main section is 46 m (151 ft) wide and sits on 3 rows of 4 caterpillar track assemblies, each 3.8 m (12 ft) wide. The large surface area of the tracks means the ground pressure of the Bagger 288 is very small (17.1 N/cm2 or 24.8 psi); this allows the excavator to travel over gravel, earth and even grass without leaving a significant track. It has a minimum turning radius of approximately 100 meters, and can climb a maximum gradient of 1:18.
The excavating head itself is 21.6 m in diameter and has 18 buckets each holding 6.6 cubic meters (7.9 yd³) of overburden.By February 2001, the excavator had completely exposed the coal source at the Tagebau Hambach mine and was no longer needed there. In three weeks it made a 22 kilometer (14 mile) trip to the Tagebau Garzweiler, traveling across Autobahn 61, the river Erft, a railroad line, and several roads. The move cost nearly 15 million German marks and required a team of seventy workers. Rivers were crossed by placing large steel pipes for the water to flow through and providing a smooth surface over the pipes with rocks and gravel. Special grass was seeded to smooth its passage over valuable terrain. Moving Bagger 288 in one piece was more economical than disassembling the excavator and moving it piece by piece.