Granted Patent
Utility
US 5,073,064 · App. 07/515,838
Method and apparatus for retorquing an installed mine roof bolt
Inventors:
Henry A. Leonard, Charles W. Schaffer
Patented Case
View Patent ↗
Granted: Dec 17, 1991
Filed: Apr 27, 1990
Inventors
Henry A. Leonard
Charles W. Schaffer
Assignee (at issue)
Birmingham Bolt Co., Inc.
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.