Patent ID: 8109179
Filing Date: 2012-02-07
Classification: E21B

Abstract:
1. An apparatus including a power tong for threading and unthreading a threaded joint in a tubular, the tong comprising: a rotary jaw housed within a drive section, wherein said rotary jaw includes a rotary jaw having a slot, said slot having a throat at an opening thereof, a back up jaw mounted to said drive section, said backup jaw and said drive sections having aligned openings therein, said rotary jaw adapted for three hundred sixty degree rotation relative to said drive section and said backup jaw about an axis of rotation passing through centers of said drive section, said rotary jaw and said backup jaw, said slot in said rotary jaw and said opening sized for receiving a tubular into said centers of said drive section, said rotary jaw and said backup jaw, first grippers mounted at said center of said rotary jaw, and second grippers mounted at said center of said backup jaw, said first and second grippers adapted to hold a tubular on opposite sides of a threaded joint in the tubular, said drive section having a primary drive mounted thereon selectively rotating said rotary jaw relative to said drive section and said backdrop jaw about said axis of rotation, wherein said axis of rotation is substantially coaxial with the tubular when the tubular is positioned into said centers and gripped by said first and second grippers, wherein, with the tubular gripped by said grippers, and with the threaded joint of the tubular positioned between said rotary jaw and said backup jaw, said rotation of said rotary jaw about said axis of rotation and driven by said primary drive urges relative rotation between oppositely disposed ends of the tubular oppositely disposed on either side of the threaded joint, wherein a secondary drive is mounted on said drive section, and wherein gripper actuators are mounted to said rotary jaw, and wherein said gripper actuators cooperate with so as to selectively actuate said first grippers whereby said rotary jaw forms a substantially self-contained three hundred sixty degree rotatable tubular gripping system for gripping the tubular and rotation thereof about said three hundred sixty degrees of rotation relative to said drive section and said backup jaw, and wherein a nested transmission is mounted in said drive section in cooperation with said rotary jaw to provide power from said secondary drive to said gripper actuator, wherein said nested transmission includes a first set of sprockets rotatably mounted to said drive section, a flexible serpentine member mounted around said first set of sprockets so as to cooperate with and be driven by said secondary drive, and a second set of sprockets rotatably mounted to so as to cooperate with said rotary jaw wherein a flexible synchronizing member is mounted around said second set of sprockets, wherein said first and second sets of sprockets are nested relative to one another so that said second set of sprockets is nested closely adjacent within said first set of sprockets substantially concentrically around said axis of rotation, and wherein said first set of sprockets and at least one said flexible serpentine member forms at least one C section serpentine drive loop, said at least one C section serpentine drive loop positioned around, so as to not interfere with access of a tubular into, said openings in said back-up jaw and said drive section, and wherein said second set of sprockets and at least one said flexible synchronizing member forms at least one synchronization, drive loop, said at least one synchronization drive loop positioned around, so as to not interfere with, said throat and said slot in said rotary jaw, and wherein at least one of said sprockets of said second set of sprockets is in contact with, so as to be driven by, said at least one flexible serpentine member at all times as said rotary jaw is rotated relative to said drive section and said back-up jaw to thereby continuously transfer power from said drive section to said gripper actuator during when said rotary jaw is at rest and during said full three hundred sixty degrees of said rotation of said rotary jaw about said axis of rotation.