| 摘要 |
PURPOSE:To aim at enhancing the durability of a wheel lock device by disposing a cut-off valve which closes when the hydraulic pressure in a master cylinder exceeds the hydraulic pressure in a wheel cylinder, in a brake circuit, and by disposing a regulator valve in a discharge circuit for a hydraulic pump. CONSTITUTION:In a wheel lock preventing device, a control device 29 judges whether a wheel 13 is locked or not, in accordance with the output of a wheel rotational speed detecting sensor 25 when a the depression of a brake pedal 10 is detected in association with the closing of a switch 26, and controls the change-over of a feed/discharge change-over valve 21 when the wheel is locked. In this arrangement, a normally open cut-off valve V1 which is close when the pressure in a master cylinder 11 exceeds the pressure in a wheel cylinder 12 is disposed in pipe lines 31, 32 connecting between the master cylinder 11 and the feed/discharge change-over valve 21. Further, a regulator valve 2 which regulates the discharge pressure of a hydraulic pump 23 at a regulated pressure slightly higher, by a predetermined value, than a reference pressure equal to the hydraulic pressure in the wheel cylinder 12, is disposed in a discharge pipe line 38.
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