Granted Patent
Utility
US 6,682,268 · App. 09/944,666
Method and apparatus for secondary roof support in an underground mine
Inventors:
Roy Lee Robertson, Jr., James Earl
Patented Case
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Granted: Jan 27, 2004
Filed: Aug 31, 2001
Inventors
Roy Lee Robertson, Jr.
James Earl
Assignee (at issue)
Earl Products, 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.