Definitions for "Kelly bushing"
Keywords:  rotary, bushing, datum, torque, drill
a special device that, when fitted in to the master bushing, transmits torque to the kelly and simultaneously permits vertical movement of the kelly to make hole. It may be shaped to fit the rotary opening or have pins for transmitting torque. Also called the drive bushing. See kelly.
KB. The heavy bushing at the rotary table, through which the kelly passes, which transmits the rotary motion of the rotary table to the drill pipe. The top of the bushing is often taken as a depth datum.
n: a device fitted to the rotary table through which the kelly passes and the means by which the torque of the rotary table is transmitted to the kelly and to the drill stem. Also called the drive bushing.