Granted Patent
Utility
US 6,192,681 · App. 09/077,552
Hydraulic drive apparatus
Inventors:
Yasutaka Tsuruga, Takashi Kanai, Junya Kawamoto
Patented Case
View Patent ↗
Granted: Feb 27, 2001
Filed: Jun 1, 1998
Inventors
Yasutaka Tsuruga
Takashi Kanai
Junya Kawamoto
Assignee (at issue)
HITACHI CONSTRUCTION MACHINERY CO., LTD.
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.