A mechanical-double ring-hydraulic composite transmission mechanism includes an input member, a convergence mechanism, a hydraulic transmission mechanism, a double ring mechanism, an output member, a clutch assembly, and a brake assembly. The clutch assembly connects a left planetary gear train to a right planetary gear train. The clutch assembly connects the input member to the hydraulic transmission mechanism, the double ring mechanism, the left planetary gear train, and the right planetary gear train. The clutch assembly connects the hydraulic transmission mechanism to the right planetary gear train. The clutch assembly connects the double ring mechanism to the left planetary gear train. The clutch assembly connects the left planetary gear train and the right planetary gear train to the output member. A continuous transmission ratio between the input member and the output member is provided by adjusting a displacement ratio of the hydraulic transmission mechanism.

A vehicle transmission having a housing and a main transmission which includes input and output shafts and four planetary gearsets. Each of the gearsets has sun and ring gears, a carrier which supports a planetary gearwheel. The sun gear and the carrier of the second gearset are coupled permanently to the input and output shafts, respectively. The carrier of the second gearset is permanently coupled to the carrier of the fourth gearset. The ring gear of the second gearset is permanently coupled to the ring gear of the third gearset. The carrier of the fourth gearset can be coupled, via a first shifting element, to the sun gear of the second gearset. The carrier of the third gearset can be coupled, via a second shifting element, to the housing. The sun gear of the third gearset can be coupled, via third and fourth shifting elements, to the input shaft.

A mechanical-double ring-hydraulic composite transmission mechanism includes an input member, a convergence mechanism, a hydraulic transmission mechanism, a double ring mechanism, an output member, a clutch assembly, and a brake assembly. The clutch assembly connects a left planetary gear train to a right planetary gear train. The clutch assembly connects the input member to the hydraulic transmission mechanism, the double ring mechanism, the left planetary gear train, and the right planetary gear train. The clutch assembly connects the hydraulic transmission mechanism to the right planetary gear train. The clutch assembly connects the double ring mechanism to the left planetary gear train. The clutch assembly connects the left planetary gear train and the right planetary gear train to the output member. A continuous transmission ratio between the input member and the output member is provided by adjusting a displacement ratio of the hydraulic transmission mechanism.

A transmission between a drive aggregate and a drive output of a vehicle drivetrain has a hydrodynamic starting element and a powershiftable main transmission with a plurality of forward gears, at least one reversing gear, a transmission input, a transmission output, and frictional shifting elements. In each gear a first number of shifting elements are closed and a second number of shifting elements are open. A downstream range group has at least one interlocking shifting element which can be shifted between a first and second driving ranges. With the drive aggregate running, the vehicle at a standstill or nearly so, the main transmission in neutral, and a shift request received to change the downstream range group, shifting elements of the main transmission are actuated, thereby bracing the transmission input against a transmission housing and decoupling the transmission input from the transmission output. The downstream range group is then shifted.