Abstract: An anti-lock vehicle brake system includes a source of fluid pressure, a wheel brake connected to source of fluid pressure and an anti-lock control valve for relieving pressure at the brake. Sensing and control apparatus are provided for positioning the control valve. A restriction apparatus limits the flow of fluid pressure to the brake. A fluid flow control is provided intermediate the anti-lock control valve and the restriction apparatus for control of the restriction apparatus.

Abstract: A detector for an anti-lock vehicle brake system in which a d.c. signal proportional to wheel speed is produced and compared against a rate of change reference signal. An output control signal is produced when the rate of change of the wheel speed signal exceeds the rate of change of the reference signal.

Abstract: An electronic control circuit for an anti-lock vehicle brake system which includes apparatus responsive to an input signal having a quantity which is a function of wheel speed to produce an output signal for causing energization of a solenoid valve when the quantity undergoes a change corresponding to a change in wheel speed at a rate in excess of a first predetermined rate of change of wheel speed and by an amount which is greater by a given percentage than its amount of change would have been had its change of wheel speed continued at said first predetermined rate of change. The latter corresponds to a reference rate of wheel deceleration. Other apparatus responsive to the input signal when the output signal is produced to store an initial reference velocity signal that has a predetermined relationship with the actual wheel speed to which the value of the quantity then existing corresponds.