Granted Patent
Utility
US 4,394,787 · App. 05/928,403
Hydraulic door closer construction
Inventor:
Sidney Lieberman
Patented Case
View Patent ↗
Granted: Jul 26, 1983
Filed: Jul 27, 1978
Inventor
Sidney Lieberman
Assignee (at issue)
Dorma Door Controls, 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.