FIELD: automotive industry; vehicle brake control systems. SUBSTANCE: device has master cylinder, pneumatic booster and control rod. Booster has rigid housing divided by movable partition into two chambers with no leakage of liquid from chamber to chamber. Partition is set in operation under action of pressure differential between chambers built at opening of three-way valve. Main hydraulic piston 30 of master cylinder has hollow movable cylinder 32 connected with inner space V of master cylinder. Second hydraulic piston 34 moves inside hollow movable cylinder with no leakage of liquid. Second hydraulic piston 34 has normally open two- way valve gear 56 which can interrupt communication between inner space V of master cylinder and space 35 of movable cylinder 32. Piston 34 is made sectional. It has the first part 50 which is pressed to movable cylinder 32 under action of first flexible device 46, when brake is not applied, and second part 52 which can be displaced relative to first part 50. Second flexible device is provided which applies force to second part 52 in rearward direction to set second part in contact with first part 50, when brake is not applied. EFFECT: improved performance characteristics, simplified design. 14 cl, 8 dwg
