Patents Represented by Attorney, Agent or Law Firm Clayton R. Johnston
  • Patent number: 6425449
    Abstract: The drilling apparatus includes a wire line core barrel head assembly that has a latch body seatable on a drill string landing shoulder and retained in a latch seated position by a latch assembly spring urged to a latch seated position, fluid seals on the latch body to facilitate fluidly propelling the head assembly in an upward direction, valve mechanism in a latch body bypass channel to restrict fluid flow therethrough to provide a signal of the latch body seating on the landing shoulder and then opening together with being retractable to an open position by a latch retractor prior to the latch body being retracted and second valve mechanism to block axial outward flow in the bypass channel. The fluid seals are mounted to a latch body adaptor that may be removed to convert from an up-hole to a down-hole assembly.
    Type: Grant
    Filed: February 8, 2001
    Date of Patent: July 30, 2002
    Assignee: Boart Longyear International Holdings, Inc.
    Inventor: John C. Marshall