Granted Patent
Utility
US 4,336,840 · App. 06/213,871
Double cylinder system
Inventor:
Thomas F. Bailey
Patented Case
View Patent ↗
Granted: Jun 29, 1982
Filed: Dec 8, 1980
Inventor
Thomas F. Bailey
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.