A brake system for motor vehicles with an antilock control device is demonstrated. A pump is provided which in the control mode delivers a reduced volume for positioning of a piston of the master cylinder. In the embodiment according to Fig. 2, reduction of the volumetric delivery is achieved in that the non-return valve (64, 65) is kept open. As a result the movements of the piston (56) are rendered ineffective with regard to the delivery of pressure medium. The non-return valve (64, 65) is kept open by a solenoid actuating unit (62). The actuating unit is controlled by the electronic control unit of the antilock device. In this way, it is ensured by simple means that at least one piston of the master cylinder and hence the brake pedal are arbitrarily positioned whilst in the control mode. <IMAGE>
