Granted Patent
Utility
US 4,934,873 · App. 07/229,705
Mine roof support utilizing roof anchors having eye-bolt heads
Inventor:
Frank Calandra, Jr.
Patented Case
View Patent ↗
Granted: Jun 19, 1990
Filed: Aug 8, 1988
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.