Granted Patent
Utility
US 4,969,778 · App. 07/429,752
Expansion assembly for mine roof bolts utilized in small diameter bore holes
Inventors:
Frank Calandra, Jr., Mike Cokus, John C. Stankus, Paul Yacisin
Patented Case
View Patent ↗
Granted: Nov 13, 1990
Filed: Oct 30, 1989
Inventors
Frank Calandra, Jr.
Mike Cokus
John C. Stankus
Paul Yacisin
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.