Granted Patent
Utility
US 4,452,539 · App. 06/314,784
Bearing seal for rotating cutter drill bit
Inventors:
Robert F. Evans, Randy C. Davis
Patented Case
View Patent ↗
Granted: Jun 5, 1984
Filed: Oct 26, 1981
Inventors
Robert F. Evans
Randy C. Davis
Assignee (at issue)
Varel Manufacturing Company
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.