Alternatively, some say the name kelly is derived from the machine shop in which the first kelly was made. It was located in a town formerly named Kellysburg, Pennsylvania.
A long square or hexagonal steel bar with a hole drilled through the middle for a fluid path. The kelly is used to transmit rotary motion from the rotary table or kelly bushing to the drillstring, while allowing the drillstring to be lowered or raised during rotation.
The Delmag Kelly Bar (one of their most frquently used options) which is a telescopic drilling rod, is used for Kelly drilling works to transfer the torque and pre-stressing forces to the auger tool. The length of the Kelly bar and the auger defines the maximal reachable drilling depth.
