The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jan. 26, 2021
Filed:
Mar. 07, 2018
Hitachi Construction Machinery Co., Ltd., Tokyo, JP;
Shinichiro Tanaka, Hyogo, JP;
Hitachi Construction Machinery Co., Ltd., Tokyo, JP;
Abstract
This hydraulic drive device for a work vehicle includes a main pump () of a variable displacement type or a fixed displacement type discharging pressure oil, a main flow passage (F) for supplying pressure oil of the main pump to an actuator, a sub-pump () of a fixed displacement type discharging pressure oil, a sub-flow passage (F) for making pressure oil of the sub-pump merge with the main flow passage and supplying the pressure oil to the actuator (), a merging directional valve (A) for connecting or cutting off the main flow passage and the sub-flow passage, a controller () for controlling operation of the merging directional valve, and a relief valve (A) arranged in the sub-flow passage, in which the relief valve has a pressure override characteristic having a tendency that the relief pressure increases from a cracking pressure to a set pressure as a relief flow rate increases.