Granted Patent
Utility
US 4,273,284 · App. 05/926,968
Insulated rail joint
Inventor:
Thomas N. Hannigan
Patented Case
View Patent ↗
Granted: Jun 16, 1981
Filed: Jul 21, 1978
Inventor
Thomas N. Hannigan
Assignee (at issue)
Portec, 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.