Hitachi Construction Machinery Co., Ltd.

Takehiko Katsuragi

Koji Hyodo

Kazuo Ishida

Tadayoshi Aoki

Shoroku Kawahara

Tsuyoshi Takeyama

There are provided: an HST hydraulic circuit that is formed through a closed circuit connection of a variable displacement hydraulic pumpand first and second variable displacement hydraulic motorsand; a charge pumpthat replenishes the HST hydraulic circuit with hydraulic oil; a cooling circuit through which an excess of the hydraulic oil that has been replenished from the charge pumpto the HST hydraulic circuit is returned to a reservoir through the hydraulic pump, the first hydraulic motor, and the second hydraulic motor; a hydraulic sourcethat supplies hydraulic oil to an hydraulic device other than the first and second hydraulic motors; and a merge circuit through which a portion of hydraulic oil from the hydraulic sourceis merged into an intermediate oil linethat lies downstream of the first hydraulic motorand upstream of the second hydraulic motorin the cooling circuit.

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Kasumigaura, Japan

Takehiko Katsuragi