Kanzaki Kokyukoki Mfg. Co., Ltd.

Nobuhiko Ichinose

Minoru Kamada

At least one of first and second hydraulic motor units that drive first and second wheels is of a variable displacement. A volume adjusting mechanism thereof is operated by an electric motor in accordance with manual operation or automatic operation based on difference in turning radius between the first and second wheels. A control device that controls the electric motor includes normal mode that operates the electric motor in accordance with the manual operation or the automatic operation and torque-up mode that fixes the variable displacement hydraulic motor to a first volume larger than a standard volume, and activates the torque-up mode at idling state in which a power source is in operating state and a pump-side volume adjusting mechanism is in neutral state and shifts the torque-up mode to the normal mode when a traveling speed reaches a first speed.

Hydraulic four-wheel-drive work vehicle

Provided an electrically-operated hydraulic actuator unit that includes an electrically-operated motor controlled by a control apparatus and actuating a volume adjusting mechanism through driving-side and driven-side arms, and a clutch mechanism in which the driven-side arm presses a contact member against a clutch case so that the driven-side arm is locked when a force from the volume adjusting mechanism is applied to the driven-side arm. The control apparatus can set duties of first to fourth drive signals to be output to the electrically-operated motor in a neutral-side start period, a neutral-side ordinary actuation period, a higher-volume-side start period and a higher-volume-side ordinary actuation period. The duties of the first and fourth drive signals are larger than that of the second drive signal, the duty of the third drive signal is larger than that of the fourth drive signal, and an integrated ON-time of the third drive signal is larger than that of the first drive signal.

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Osaka, Japan

Nobuhiko Ichinose