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AssigneeHitachi Construction Machinery Co., Ltd.
InventorsTsuyoshi Nakamura, Toichi Hirata, Genroku Sugiyama, Tsukasa Toyooka, Youichi Kowatari, Kouji Ishikawa
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A hydraulic system for a construction machine includes a hydraulic pump driven by a prime mover, actuators driven by a hydraulic fluid delivered from the hydraulic pump, flow control valves for controlling flow of the hydraulic fluid to the actuators and operation means for operating the flow control valves. A relief value sets a relief pressure for limiting the maximum delivery pressure of the hydraulic pump and relief pressure change means increase or decrease the relief pressure set by the relief valve. The relief pressure change means automatically increase or decrease the relief pressure in accordance with the input amount of the operation means.
A hydraulic drive system for a construction machine comprising a hydraulic pump driven by a prime mover, actuators driven by a hydraulic fluid delivered from said hydraulic pump, flow control valves for controlling flow of the hydraulic fluid supplied from said hydraulic pump to said actuators, operation means for operating said flow control valves, a relief valve for setting a relief pressure for limiting the maximum delivery pressure of said hydraulic pump, and relief pressure change means for increasing or decreasing said relief pressure set by the relief valve;
Dependencies are inferred from the claim text.