Granted Patent
Utility
US 5,133,449 · App. 07/620,069
Frictional drive spiral conveyor system
Inventor:
Michael L. Spangler
Patented Case
View Patent ↗
Granted: Jul 28, 1992
Filed: Nov 30, 1990
Inventor
Michael L. Spangler
Assignee (at issue)
Cambridge Wire Cloth Company
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.