Granted Patent
Utility
US 4,903,786 · App. 07/210,682
Earth boring bit with improved two piece bearing and seal assembly
Inventor:
Michael F. Welsh
Patented Case
View Patent ↗
Granted: Feb 27, 1990
Filed: Jun 23, 1988
Inventor
Michael F. Welsh
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.