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:
Dec. 28, 2021
Filed:
Dec. 25, 2018
Hitachi Construction Machinery Co., Ltd., Tokyo, JP;
Hitachi Construction Machinery Co., Ltd., Tokyo, JP;
Abstract
A hydraulic drive system includes a swing directional control valveand a third boom directional control valvethat are connected to a third hydraulic pump. Furthermore, the hydraulic drive system includes: a second auxiliary directional control valvethat is connected to the third hydraulic pump, and is connectable with a second special hydraulic actuatorfor driving special attachments; and a first selector valvethat is connected to the third hydraulic pumpupstream of the second auxiliary directional control valve, and is connectable with an additional hydraulic pump. The first selector valveswitches the hydraulic fluid source of the second special hydraulic actuatorconnected to the second auxiliary directional control valveat least between the third hydraulic pumpand the additional hydraulic pump. Operability for combined operation of a special attachment can be improved in the hydraulic drive system equipped in advance with an auxiliary directional control valve that is connectable with an additional hydraulic actuator for driving the special attachment.