Patents Examined by Richard F. Favreau
  • Patent number: 4244433
    Abstract: A raise bit is disclosed for enlarging a pilot hole into a larger diameter hole by disintegrating the earth formations surrounding the pilot hole. The raise bit includes a removable drive stem for enabling the raise bit to be transported through small drifts. The drive stem is attached to a thrust bearing plate which, in turn, is interconnected to a main bit body. The bit body extends around the drive stem and includes a plurality of rolling cutters for contacting and disintegrating the earth formations surrounding the pilot hole. The interconnection between the thrust bearing plate and the bit body is accomplished by means of a flexible shock absorbing member which is bonded to the plate and bit body. This flexible interconnection functions to absorb the bending and impact type loads acting on the bit body. A safety mechanism is provided to limit the amount of relative axial movement of the flexibly interconnected members should the bonded interconnections separate.
    Type: Grant
    Filed: December 26, 1978
    Date of Patent: January 13, 1981
    Assignee: Smith International, Inc.
    Inventor: Jackson M. Kellner