The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Nov. 23, 1976
Filed:
Jan. 19, 1976
Howard E Mitchell, Duncanville, TX (US);
Dresser Industries, Inc., Dallas, TX (US);
Abstract
A raise bit for enlarging a pilot hole into a larger diameter hole by disintegrating the earth formations that surround the pilot hole is provided with a removable drive stem. The removable drive stem allows the raise bit to be transported through small passages and helps extend the useful lifetime of the bit. The bit may be assembled without weakening the highly-stressed, heat-treated stem by welding. The raise bit body includes a multiplicity of rolling cutters for contacting and disintegrating the earth formations surrounding the pilot hole. A central opening extends through the bit body. The central opening includes an upward facing tapered surface. The lower end of the drive stem extends through the central opening. A downward facing tapered surface on the drive stem mates with the upward facing tapered surface on the bit body. The lower end of the drive stem is threaded to receive a threaded nut which draws the tapered surfaces together.