A torque converter and a planetary gear set therefor, said planetary gear set having two sets of clutches wherein one element among a sun gear, a ring gear and a planetary carrier is connected directly to an input shaft, another element is connected directly to an impeller of said torque converter and the other element is connected to an output shaft via one of said clutches. A power absorption capability of the torque converter may be varied in two stages in order to meet separate demands for engine power which occur during various operating phases of vehicle operation.