| 摘要 |
PURPOSE:To secure the fail-safe function when a front side brake fails, by partitioning a pressure chamber in the housing of a control valve and introducing the brake hydraulic pressure on the front side into the pressure chamber and pressing a stepped piston against the brake hydraulic pressure of a master cylinder. CONSTITUTION:A stepped piston 40 having a penetration hole 40c is installed into a hollow hole 31a formed on a housing 32, and a pressure chamber 49 is partitioned between the first hollow hole part 33 and the second piston part 40b by the hollow hole step difference surface 31a and the piston step difference surface 40d. Further, the brake hydraulic pressure PF on a front wheel side is introduced into the pressure chamber 49, and the stepped piston 40 is pressed in the B direction by the force PFXA1 together with the urging force F1 of a coil spring 41. The stepped piston 40 is pressed in the B direction against the pressing force PRXA2 in the A direction of the brake hydraulic pressure PR of a master cylinder which acts onto the stepped piston 40 through a penetration hole 40C. Therefore, the fail-safe function of the hydraulic control valve in the case when the front side brake is broken can be secured.
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