دیکشنری تخصصی مهندسی نفت - نسخه آنلاین

n: a kelly bushing that has four steel dowels. or pins. that fit into corresponding holes in the master bushing. When the pins are engaged with the holes. the rotating master bushing also turns the kelly bushing. which then turns the kelly and the drill stem. See kelly, kelly bushing, master bushing.

n: a feature on four-pin kelly bushings installed on floating offshore rigs (which employ a conventional rotary table assembly) that secures the kelly bushings pins to the master bushings corresponding drive holes so that the kelly bushing will not separate from (lift off of) the master bushing as the rig heaves up and down with wind and wave motion. See kelly bushing, master bushing.