Granted Patent
Utility
US 4,620,601 · App. 06/306,290
Well drilling tool with diamond thrust bearings
Inventor:
Dave D. Nagel
Patented Case
View Patent ↗
Granted: Nov 4, 1986
Filed: Sep 28, 1981
Inventor
Dave D. Nagel
Assignee (at issue)
Maurer Engineering GmbH
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.