Vehicle transmission system and method for operation of the transmission system

A method for operation of a transmission system in a vehicle, comprising:

• executing a first coordinated operation of a first brake device and a first lock-up clutch coupled to a first ring gear in a first planetary gear set to transition the transmission system between a first gear ratio mode and a second gear ratio mode, wherein the first brake device and the first lock-up clutch ground the first ring gear in parallel during the coordinated operation;
• wherein the transmission system comprises:
• the first planetary gear set;
• a second planetary gear set including a second ring gear;
• and
• a third planetary gear set including a third ring gear;
• wherein sun gears of the first, second, and third planetary gear sets are coupled in series.

An automatic transmission system, comprising:

• a first planetary gear set comprising a first ring gear and a first sun gear;
• a second planetary gear set coupled to the first planetary gear set and comprising a second ring gear and a second sun gear;
• a third planetary gear set coupled to the second planetary gear set and comprising a third ring gear and a third sun gear;
• a first brake device configured to selectively ground the first ring gear;
• a second brake device configured to selectively ground the first ring gear;
• a first lock-up clutch configured to selectively ground the first ring gear in parallel with the first brake device;
• and
• a controller including executable instructions stored in non-transitory memory that cause the controller to:
• coordinate operation of the first lock-up clutch, the first brake device, and the second brake device to transition the automatic transmission system between a first gear ratio mode and a second gear ratio mode.