HYDRAULIC PRESSURE RETAINING DEVICE

摘要

PROBLEM TO BE SOLVED: To provide a hydraulic pressure retaining device which can be provided on an HST vehicle with suppressing increase in production cost of the HST vehicle and increase in size of a hydraulic pressure circuit of the HST vehicle.

SOLUTION: The hydraulic pressure retaining device includes a hydraulically piloted negative type parking brake 51 constituting a parking brake as one of hydraulically actuated sections installed on the HST vehicle and releasing the brake of an oil hydraulic motor 24 for travel by using a charge pressure as a release pressure, a change-over valve 52 capable of switching fluid communication/shutoff between a charge circuit 30 and the release pressure of the negative type parking brake 51 and a check valve 53 which prevents pressured oil from flowing in the direction from an oil passage 40 toward the charge circuit 30. When the charge pressure falls down, the negative type parking brake 51 is used as a hydraulic power source to retain the pressure in the oil passage 40.

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