Granted Patent
Utility
US 4,508,550 · App. 06/489,369
Air flow responsive outlet from tank of vacuum cleaner
Inventors:
Robert C. Berfield, Robert L. Crevling, Jr., Lonnie B. Lawson, Jr.
Patented Case
View Patent ↗
Granted: Apr 2, 1985
Filed: Apr 28, 1983
Inventors
Robert C. Berfield
Robert L. Crevling, Jr.
Lonnie B. Lawson, Jr.
Assignee (at issue)
SHOP VAC 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.