摘要 |
An anti-lock braking system having a wheel brake, a hydraulic control circuit for controlling the supply of a hydraulic control pressure to the wheel brake, and an electronic control circuit for energizing the hydraulic control circuit so as to reduce the hydraulic braking pressure applied to the wheel brake when the wheel is about to be locked due to the rotational speed characteristics thereof, characterized in that the electronic control circuit has the function of detecting the condition of a road surface on which a vehicle runs, and is formed in such a manner that, when the electronic control circuit judges that the road surface is rough, it is operated so that it employs the highest wheel speed of the two wheel speed signals, and when the road surface is judged not to be rough respective wheel speed signals are employed by the electronic control circuit for operation of their respective hydraulic control circuits. The electronic control circuit is adapted to judge that, when the fluctuating frequency of a wheel speed is not less than a predetermined level, the road surface on which the vehicle runs is rough.
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