The rotary drilling rig is the key machine in specialized deep foundation work for the construction of large-diameter bored piles, diaphragm walls, and ground improvement. It drills cylindrical holes into the ground through rotary drive of a drilling tool (bucket auger, continuous flight auger, or casing) — typically with diameters of 600 mm to 3,000 mm and depths exceeding 100 meters.
The machine comprises a crawler chassis, the mast (kelly bar or continuous auger), the rotary table or drilling drive, and a rope winch. Kelly drilling methods operate with telescoping kelly bars and interchangeable drilling tools, while the CFA method (Continuous Flight Auger) continuously conveys soil upward.
Leading manufacturers include Bauer Maschinen (BG series), Liebherr (LB series), Casagrande, and Soilmec. BAUER is the global market leader in large rotary drilling rigs with the BG 15 through BG 72 series. Modern machines are equipped with GPS positioning, automatic verticality control, and drilling data logging systems.