Granted Patent
Utility
US 4,955,949 · App. 07/305,319
Mud saver valve with increased flow check valve
Inventors:
Thomas F. Bailey, Raymond A. Todd, Jr.
Patented Case
View Patent ↗
Granted: Sep 11, 1990
Filed: Feb 1, 1989
Inventors
Thomas F. Bailey
Raymond A. Todd, Jr.
Assignee (at issue)
Drilex Systems, Inc.
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.