Apparatus for the prevention of wheel locking in motor vehicles

Claim 1

In a wheel lock prevention apparatus for motor vehicles having a first and second braking circuit forming part of a two circuit braking system, with a pressure transducer for each circuit and two groups of pressure receivers, the system further including a wheel lock prevention valve assembly connected to said circuits, vehicle wheel sensors connected to said valve assembly, and an electronic control device connected to said sensors and said valve assembly, said control device processes the signals sensed by the sensors and transmits them to the valve assembly, said valve assembly including therein at least one reduction valve having a control volume and an electromagnetic valve pair connectible with the control volume of the reduction valve and serving as an inlet and outlet valve for the control volume of the reduction valve, the improvEment comprising a switching valve connected to said second braking circuit and to a pressure medium within said first braking circuit and means connecting said electromagnetic valve pair to the pressure medium within said first braking circuit, wherein the electromagnetic valve pair controls the two braking circuits by controlling the pressure medium of the first braking circuit, which pressure medium actuates said switching valve, wherein when the pressure in said second braking circuit is low with respect to the pressure in said first braking circuit, said switching valve closes the passage through said second braking circuit, and wherein when the pressure in said second braking circuit is high with respect to the pressure in said first braking circuit, said switching valve opens a passage through said second braking circuit.