Granted Patent
Utility
US 5,425,601 · App. 08/151,791
Longwall mining roof control system
Inventors:
Frank Calandra, Jr., John C. Stankus
Patented Case
View Patent ↗
Granted: Jun 20, 1995
Filed: Nov 12, 1993
Inventors
Frank Calandra, Jr.
John C. Stankus
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.