Granted Patent
Utility
US 4,537,233 · App. 06/506,276
Spring balance assembly
Inventors:
Evart. J. Vroonland, William M. Curtis
Patented Case
View Patent ↗
Granted: Aug 27, 1985
Filed: Jun 21, 1983
Inventors
Evart. J. Vroonland
William M. Curtis
Assignee (at issue)
Continental Emsco 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.