A lock-up device for a torque converter is disclosed. The lock-up device includes a clutch part, first and second rotary members, a plurality of elastic members and a stopper mechanism. The clutch part is provided between a front cover and a turbine, and transmits the torque inputted to the front cover to the turbine. The first rotary member is disposed between the clutch part and the turbine. The second rotary member is rotatable relative to the first rotary member. The elastic members elastically couple an outer peripheral part of the first rotary member and an outer peripheral part of the second rotary member in a rotational direction. The stopper mechanism is disposed axially between the elastic members and an outer peripheral part of a turbine shell. The stopper mechanism includes an engaging portion restricting an angular range of relative rotation between the first rotary member and the second rotary member.

A power transmission device includes an input-side rotary part to which a torque is inputted from an engine, an output-side rotary part, and a damper part. The output-side rotary part includes a first rotor and a second rotor. The first rotor is configured to be rotatable relative to the input-side rotary part. The first rotor is configured to be rotatable unitarily with the input-side rotary part at greater than or equal to a predetermined relative rotational angle. The second rotor is configured to be rotatable unitarily with the first rotor. The second rotor is configured to be rotatable relative to the first rotor at greater than or equal to the predetermined relative rotational angle. The damper part is configured to elastically couple the input-side rotary part and the output-side rotary part.

A lock-up device for a torque converter is disclosed. The lock-up device includes a clutch part, first and second rotary members, a plurality of elastic members and a stopper mechanism. The clutch part is provided between a front cover and a turbine, and transmits the torque inputted to the front cover to the turbine. The first rotary member is disposed between the clutch part and the turbine. The second rotary member is rotatable relative to the first rotary member. The elastic members elastically couple an outer peripheral part of the first rotary member and an outer peripheral part of the second rotary member in a rotational direction. The stopper mechanism is disposed axially between the elastic members and an outer peripheral part of a turbine shell. The stopper mechanism includes an engaging portion restricting an angular range of relative rotation between the first rotary member and the second rotary member.

A torsional damper for a torque transmission device, comprising: a rotationally movable first element (102) and second element (103); and an elastically deformable blade (117a, 117b) integral with one of the first and second elements; an abutment element (121) carried by the other of the first and second elements and configured to interact with the blade in such a way that for an angular deflection between the first and second elements with respect to an inactive angular position, the abutment element applies a flexural load onto the blade, producing jointly a reaction force capable of returning the first and second elements to the inactive angular position, blade has an inner arm (132) and an outer arm (134) connected by a bend (133), the inner arm being situated radially between the outer arm and a rotation axis.

A lock-up device includes a drive plate, a driven plate, first torsion springs, second torsion springs, a spring holder and a rotation restricting unit. The rotation restricting unit is configured to restrict and bring the first torsion spring in each group and the second torsion spring in each group to a deactivated state by at least either of engagement of the spring holder with the driven plate or engagement of the drive plate with the spring holder.