Granted Patent
Utility
US 4,545,587 · App. 06/673,545
Coaxial, multiple-shaft ferrofluid seal apparatus
Inventor:
Donald W. Higgins
Patented Case
View Patent ↗
Granted: Oct 8, 1985
Filed: Nov 20, 1984
Inventor
Donald W. Higgins
Assignee (at issue)
Ferrofluidics 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.