Granted Patent
Utility
US 4,753,304 · App. 07/023,178
Volume and pressure balanced rigid face seal for rock bits
Inventor:
Joseph L. Kelly, Jr.
Patented Case
View Patent ↗
Granted: Jun 28, 1988
Filed: Mar 9, 1987
Inventor
Joseph L. Kelly, Jr.
Assignee (at issue)
Hughes Tool Company LLC
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.