Abstract: In an anti-skid vehicle braking system an electronic control unit is arranged to control the operation of an anti-skid valve assembly for modulating the fluid pressure applied to a brake actuator. A wheel speed sensor measures the speed of a braked wheel and produces a signal which is converted into a deceleration signal by a conditioning circuit and a differentiator and compared in a comparator with a deceleration threshold value. A pressure sensor provides a pressure signal corresponding to the current brake actuator pressure and a pressure signal conditioning circuit modifies the pressure signal to take account of a load signal produced by a load sensor which measures the loading of the braked wheel. The deceleration threshold value is produced by modulation of a constant threshold value in a threshold generator circuit and a threshold modulator circuit in response to the modified pressure signal.

Abstract: An anti-skid brake conrol system includes a sensor which produces a signal proportional to the acceleration of a braked wheel and a comparator that responds to the acceleration signal by producing a signal which undergoes a step change at set acceleration levels so as to divide successive deceleration/acceleration cycles into successive acceleration periods separated by intermediate periods. The output of the comparator is integrated to produce an output signal which changes in a progressive manner in one sense during each acceleration period and in the opposite sense during each intermediate period so as to vary in accordance with surface friction conditions. The output signal is used to vary a control parameter or function within the system in accordance with the surface friction conditions.

Abstract: An anti-lock brake control system for a vehicle with braked wheels comprises a sensor to produce a signal proportional to the deceleration/acceleration of the braked wheel, a deceleration sensing switch to respond to the deceleration/acceleration signal by producing a brake pressure release pulse when deceleration of the wheel exceeds a predetermined threshold level, a charge storage device which is adapted so that it charges in a predetermined progressive manner while the brake pressure release pulse is produced and discharges at a predetermined decay rate, a comparator that compares the potential on the charge storage device with a reference potential and produces an extension brake pressure release pulse according to their relative values, and apparatus to vary one of said potentials in a manner dependent on acceleration of the wheel above a preset acceleration threshold so that the extension brake pressure release pulse is terminated by increasing wheel acceleration.

Abstract: In an anti-lock brake control system for a vehicle with braked wheels, a brake pressure release pulse is produced in a manner dependent on wheel deceleration and is processed so that it cannot exceed a preset maximum length and is spaced from any other brake pressure release pulses by a preset inhibit period so that brake pressure release pulses cannot be produced above a certain maximum repetition frequency. A deceleration sensing switch produces an output pulse, and a pulse circuit is triggered by the leading edge of the output pulse to commence said brake pressure release pulse, and is reset by the lagging edge of said output pulse to terminate said brake pressure release pulse. A pulse timing circuit is also triggered by the leading edge of said output pulse and operates to terminate said brake pressure release pulse after said predetermined maximum duration if it has not been terminated already.

Abstract: An anti-lock brake control system for vehicles with braked wheels comprising a wheel speed sensor for producing a signal proportional to wheel speed; a first switch having an input connected to the sensor to receive the wheel speed signal and being adapted to respond to the rate of change of said signal so as to produce a first control pulse to effect brake pressure release while a preset first wheel deceleration threshold is exceeded; a second switch that is triggered under the control of the first control pulse and which, when triggered, initiates a second control pulse to effect brake pressure release; and a charge storage device that receives the wheel speed signal so that it accumulates a charge dependent on the dip in wheel speed and discharges in response to wheel speed recovery following said dip in wheel speed, and which is associated with the first and second switches so that it discharges in a predetermined manner after the first control pulse terminates and terminates the second control pulse when