Granted Patent
Utility
US 4,646,858 · App. 06/725,051
Earth boring bit with air system access
Inventor:
Robert Strickland
Patented Case
View Patent ↗
Granted: Mar 3, 1987
Filed: Apr 19, 1985
Inventor
Robert Strickland
Assignee (at issue)
Hughes Tool Company - USA
This patent predates the USPTO's electronic file wrapper — prosecution documents from this era exist only in the Patent Office's paper records. A certified copy of the file history can be ordered from the USPTO's paper archives.