Hydraulically operated braking system for a motor vehicle

The present invention relates to a hydraulically operated braking system for a motor vehicle comprising a pressure control valve device (56) including an electrically controlled pressure-increasing valve (150), wherein the opening pressure difference of the pressure-increasing valve (150) is electrically controllable and said pressure-increasing valve (150) is opened to permit the pressurized fluid to be supplied from an hydraulic pressure source (12,18,20) to at least one wheel brake cylinder when an actual pressure difference of the fluid across the pressure-increasing valve has exceeded the electrically controlled opening pressure difference, the opening pressure difference when said pressure-increasing valve (150) is not electrically controlled is smaller than a maximum pressure of the fluid pressurized by the hydraulic pressure source.