| 摘要 |
PURPOSE:To avoid the lock phenomenon of a wheel even on a road surface having a low friction coefficient by sufficiently reducing the damping force of a wheel brake in spite of a residual oil pressure when a modulator decompression- operates. CONSTITUTION:When a front wheel tends to be locked by the reduction of the friction coefficient of a road surface, the pressing force of a pressing plate exceeds a prescribed value because of the sharp increase of the angular deceleration speed of the front wheel, and a lever 91 swings to compress a spring, and the second arm 91b swings to depart from a valve body 67, and a pressure discharge valve 20 is opened. Since the oil pressure in the controlled oil pressure chamber 53 of a modulator 17 is discharged into an oil tank through oil passages 70 and 71 and a conduit, a pressure reducing piston 46 is shifted to the controlled-oil pressure chamber 53 side against the force of a spring 48 by the oil pressure in an output oil pressure chamber 55, and a valve body 60 is closed, and the communication between the oil pressure chambers 54 and 55 is cut-off, and the capacity of the output oil pressure chamber 55 is increased. Therefore, the input oil pressure of a brake reduces, and lock phenomenon can be obviated.
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