Device for a hydraulic brake system, hydraulic brake system, control device for interaction with a hydraulic braking system and method for operating a hydraulic brake system

The power unit (10) has two brake circuits (12,14) connected to a master cylinder (16) and a first wheel brake cylinder (18), and a pressure relief valve (20) which is connected on the output side of a brake fluid reservoir (22). The first portion of one of the brake circuits comprises a diverter valve (24) through which the first portion of one of the brake circuits is connected to the master brake cylinder. The first portion comprises a pressure conveying device (66) connected to the suction side of the brake fluid reservoir. Independent claims are included for the following: (1) a control device for interacting with a hydraulic brake system; and (2) a method of operating hydraulic brake system of vehicle.