Granted Patent
Utility
US 4,274,432 · App. 06/113,731
Valve
Inventors:
Karl N. Tunstall, M. L. Warren
Patented Case
View Patent ↗
Granted: Jun 23, 1981
Filed: Jan 21, 1980
Inventors
Karl N. Tunstall
M. L. Warren
Assignee (at issue)
Otis Engineering 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.