The mechanical elements of an air rotary drill rig are similar to a mud rotary rig; table drive and top-head drive are the two basic options for rotating the drill pipe. The principal difference is an air rotary rig uses compressed air to remove cuttings rather than drilling mud.
A type of ''foam'' can be added to the air stream to improve cuttings removal and provide some borehole stability. An air rotary rig can use the same type of drill bits as a mud rig, but it can also drill with a down-the-hole hammer.
This type of bit uses compressed air to break up rock and it can drill very fast. A large air rotary rig can drill a borehole 60 cm in diameter to 500 meters or more.
Because there is no drilling mud to mix or settling pits to dig, an air rotary rig can be set up very quickly. An air rotary rig also drills much faster than any other rig of a comparable size.