The Kelly is the square, hexagonal or octagonal shaped tubing and the rotary table and kelly bushing is the mechanical device the turns the kelly, and together they are referred to as a kelly drive.
The Kelly is the square tubing. This is hexagonal or octagonal shaped. The Kelly is the rotary table. This is hexagonal or octagonal shaped. Kelly bushing is the mechanical device. The turns the kelly the mechanical device. Together they are referred to as a kelly drive.