Electro-hydraulic brake system having electric control means

Claim 1

A brake system for a vehicle, comprising: a pair of brake means, each being spring-applied and hydraulically released; a source of fluid under pressure; a brake valve connected with said source of fluid and said brake means, said brake valve having formed therein a communication position where fluid under pressure is supplied to said brake means to release the same and an offset position where fluid in said brake means is drained to a tank to have said brake means spring-applied, said brake valve also having an actuating section thereof formed therein and being normally held in the communication position; first electric actuator means connected with the actuating section of said brake valve for shifting the same to the offset position when actuated; a brake pedal; first sensor means for sensing the movement of said brake pedal and generating a first signal therefrom; first controller means for actuating and controlling said first electric actuator means in accordance with the first signal received from said first sensor means; a solenoid-operated auxiliary brake valve operatively connected with the actuating section of said brake valve and said source of fluid, said auxiliary brake valve having formed therein a drain position where the actuating section of said brake valve is connected to the tank and an offset operating position where fluid under pressure is introduced therethrough to the actuating section of said brake valve for shifting the same; a brake lever for parking and emergency braking; and a first switch adapted to be switched on by the operation of said brake lever, said first switch being connected with said auxiliary brake valve for changing over the same to the offset position when it is switched on thereby shifting said brake valve to the offset position and applying said brake means.