Granted Patent
Utility
US 4,538,839 · App. 06/628,657
Pipe joint coupling
Inventor:
Harry J. Ledgerwood
Patented Case
View Patent ↗
Granted: Sep 3, 1985
Filed: Jul 6, 1984
Inventor
Harry J. Ledgerwood
Assignee (at issue)
The Plessey Company Limited
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.