Granted Patent
Utility
US 4,657,488 · App. 06/331,096
Two stage stepped piston air compressor
Inventor:
Franz Weinhandl
Patented Case
View Patent ↗
Granted: Apr 14, 1987
Filed: Dec 16, 1981
Inventor
Franz Weinhandl
Assignee (at issue)
Rockwell International 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.