Anti-skid control system for motor vehicles of the type switchable between two-wheel drive (2WD) and four-wheel drive (4WD)

Claim 1

An anti-skid control apparatus for motor vehicles having a drive system which is switchable between a two-wheel drive and a four-wheel drive, comprising: a first modulator for regulating a front lefthand wheel brake pressure; a second modulator for regulating a front righthand wheel brake pressure; a third modulator for regulating a rear lefthand wheel brake pressure; a fourth modulator for regulating a rear righthand wheel brake pressure; a plurality of speed sensors each adapted for detecting respective wheel speeds; logic circuit means for providing brake pressure control signals, on the basis of output signals derived from said plurality of speed sensors, to said first to fourth modulators; and change-over switch means provided in a circuit connecting said plurality of speed sensors to said logic circuit means, said change-over switch means being adapted so that under a two-wheel drive condition, said first and second modulators are operated independently and said third and fourth modulators are operated in synchronism with each other while under a four-wheel drive condition, said first and fourth modulators are operated in synchronism with each other and said second and third modulators are operated in synchronism with each other.