PURPOSE: To vary the capacity of a torque converter according to a vehicle speed, by rotating a rotary shaft fixing to a stator blade and varying an exit angle of the stator blade by means of a centrifugal weight varied in centrifugal force with a change in rotating speed of turbine wheel.

CONSTITUTION: A centrifugal force to be applied to a centrifugal weight 12 increases with an increase in rotating speed of a turbine wheel 4, and the weight 12 slides on an inner surface of a tapering portion 15 against an elastic force of a spring 22. Accordingly, a thrust plate 20 is moved in a direction of arrow W1 to urge a presser plate 40 in the same direction. As a result, an arm 28 is rotated with a stator blade 24 about a rotary shaft 25 in a direction of arrow W2. As a result, an exist angle α1 of the blade 24 at starting is gradually in creased to α2 at a high-speed position. Conversely, when the rotating speed of the wheel 4 decreases, the exit angle α2 is decreased to α1. Thus, the capac ity of a torque converter is changed according to a vehicle speed to thereby improve the fuel consumption and accelerating ability.