Granted Patent
Utility
US 6,408,622 · App. 09/622,957
Hydraulic drive device
Inventors:
Yasutaka Tsuruga, Takashi Kanai, Junya Kawamoto, Satoshi Hamamoto, Yasuharu Okazaki, Yukiaki Nagao
Patented Case
View Patent ↗
Granted: Jun 25, 2002
Filed: Aug 24, 2000
Inventors
Yasutaka Tsuruga
Takashi Kanai
Junya Kawamoto
Satoshi Hamamoto
Yasuharu Okazaki
Yukiaki Nagao
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.