Abstract: A method of operating a hybrid drive system with an internal combustion engine and a supplemental electric machine for a motor vehicle including first and second gear changing partial drives each with gear changing gearwheels, wherein during operation there is torque flow from one gear changing partial drive to the other partial drive results in a gear change between gearwheels.

Abstract: A method of operating a hybrid drive system with a main driving machine 11—more particularly an internal combustion engine—and a supplementary driving machine 12)—more particularly an electric machine—for a motor vehicle, comprising a first gear changing partial drive 15 with an input shaft 17 and an output shaft 23 and a first group of gear changing pairs of gearwheels each having a gearwheel connected in a rotationally fast way to its shaft and a switching gearwheel which can be switchably coupled to its shaft and whose input shaft (17) can be coupled to the main driving machine 11; a second gear changing partial drive 16 with an input shaft 18 and an output shaft 24 and a second group of gear changing pairs of gearwheels each having a gearwheel connected in a rotationally fast way to its shaft and a switching gearwheel which can be switchably coupled to its shaft and whose input shaft 18 is connectable in respect of drive to the supplementary driving machine 12 at a fixed ratio; wherein the pairs of ge