Granted Patent
Utility
US 4,678,374 · App. 06/908,338
Roof bolt with expansion shell and threaded nut
Inventor:
Frank Calandra, Jr.
Patented Case
View Patent ↗
Granted: Jul 7, 1987
Filed: Sep 17, 1986
Inventor
Frank Calandra, Jr.
Assignee (at issue)
Jennmar Corporation
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.