Hitachi Construction Machinery Co., Ltd.

Tsuyoshi Takeyama

Koji Hyodo

Masaki Yoshikawa

Yasuo Yamazaki

Kazuo Ishida

Tadayoshi Aoki

Shoroku Kawahara

Kazuo Chonan

Nobuyuki Hidaka

Takehiko Katsuragi

A control apparatus for a working vehicle includes a travel circuit HCformed through a closed circuit connection of a variable displacement hydraulic pump driven by an engine and a variable displacement hydraulic motor, a work circuit HCthat includes a work hydraulic pump driven by the engine and a work hydraulic actuator that operates by pressure oil from the work hydraulic pump, a relief valve that relieves high pressure oil of the travel circuit HC, a rotation speed control unit that controls the engine rotation speed in correspondence to an accelerator pedal operation amount, a state detection unit that detects a vehicle state of high load travel and high load work, and a speed limitation unit that reduces an engine rotation speed upper limit when the vehicle state of high load travel and high load work is detected.

Control apparatus for working vehicle

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.

HST cooling circuit

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Ryugasaki, Japan

Tsuyoshi Takeyama