Patents Examined by Nick A. Nicholas, Jr.
  • Fluid retarded accelerating jar with negative and positive pressure chambers
    Patent number: 4200158
    Abstract: A hydraulic drilling jar apparatus having axially elongated outer housing and inner mandrel members that telescope relative to each other when tripped by a predetermined axial force applied to the mandrel to deliver an impact blow to an object stuck in a well bore. A negative pressure is developed within the apparatus during initial retarded telescoping movement to effect acceleration of the mandrel member upon release at a rate exceeding the acceleration rate otherwise imposed by the axial force.
    Type: Grant
    Filed: March 3, 1978
    Date of Patent: April 29, 1980
    Assignee: Lee E. Perkins
    Inventor: Lee E. Perkins