US Patent 7360633 Lockup device of hydraulic torque transmission device

A lockup device 5 includes a damper mechanism 7, a plate 56, a plate 57, a piston 51, and a plate 59. The damper mechanism 7 has a plate 52 rotating together with the turbine 10, and plates 53 and 54 rotatable with respect to the plate 52. The plate 56 is unrotatable and axially movable with respect to the plates 53 and 54. The plate 57 is unrotatable and axially movable with respect to the front cover 2, and is arranged on the turbine side of the plate 52. The piston 51 is arranged on the turbine side of the plate 56, and is elastically and unrotatably coupled in an axial direction to the plates 53 and 54 through the plate 59.