OPERATING METHOD AND CONTROL DEVICE FOR A LONG-TERM BRAKING SYSTEM OF A VEHICLE

The invention relates to an operating method for a retarder system of a motor vehicle, wherein the retarder system comprises a primary retarder and a secondary retarder. The invention relates in particular to a method for distributing a retarder braking demand into a first portion that is requested from the primary retarder and into a second portion that is requested from the secondary retarder, as well as a control device for carrying out the method. In order to keep the heat input generated by the retarder into the cooling system as low as possible, according to general aspects of the invention, following activation of a retarder operation and until a retarder braking demand (10) for the first time exceeds a first threshold value (P_max) after activation of the retarder operation, the retarder braking demand (10) is applied by the primary retarder (2), wherein the first threshold value (P_max) is set such that it corresponds to a value that is less than or equal to a maximum braking torque generatable by the primary retarder (2). Furthermore, upon the first exceeding of the first threshold value by the retarder braking demand following activation of a retarder operation, the secondary retarder (5) is activated.