Granted Patent
Utility
US 4,019,220 · App. 05/648,627
Piston assembly for door closer
Inventor:
Sidney Lieberman
Patented Case
View Patent ↗
Granted: Apr 26, 1977
Filed: Jan 13, 1976
Inventor
Sidney Lieberman
Assignee (at issue)
Reading Door Closer Corp.
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.