Patent ID: 8857588

Claim:
A hydrokinetic coupling device ( 10 ) of a longitudinal axis of rotation (B), having a lock-up clutch ( 14 ) comprising: at least one coaxial friction disc ( 50 , 50 A, 50 B) rotating as one with a first rotary shaft and mounted axially slideable with respect to the first rotary shaft; a backing disc ( 58 ) rotating as one with a second rotary shaft and mounted such that the first backing disc is axially slideable with respect to the second rotary shaft; at least one axial abutment element ( 94 ) rotating as one with the backing disc ( 58 ), the friction disc ( 50 , 50 A, 50 B) being interposed axially between the backing disc ( 58 , 58 A, 58 B, 58 C) and the abutment element ( 94 ) for enabling a reaction to be created for clamping the friction disc ( 50 , 50 A, 50 B); a coaxial support ring ( 66 ) of the backing disc ( 58 ) rotating as one with the second rotary shaft and comprising at least one axial guide groove ( 62 B) circumferentially delineated by an upstream face ( 68 ) and by a downstream face ( 70 ), an associated radial guide tooth ( 60 B) of the backing disc ( 58 ) being housed such that the backing disc is axially slideable with circumferential play in the groove ( 62 B); a rear piston ( 38 ) moveable between a disengaged rear position in which the backing disc ( 58 ) is axially separated, and an engaged front position in which the backing disc ( 58 ) is pushed forward axially against the axial abutment element ( 94 ) clamping the intercalated friction disc ( 50 ) so as to rotationally couple the first rotary shaft with the second rotary shaft; and elastic preload means ( 82 ) comprising an elastically circumferentially deformable element ( 82 ) oriented circumferentially for exerting a preload torque to clamp the guide tooth ( 60 B) of the backing disc ( 58 ) circumferentially against one of either the upstream ( 68 ) or downstream ( 70 ) faces of the guide groove ( 62 B) of the coaxial support ring ( 66 ); the elastically deformable element ( 82 ), in its non-loaded state, is axially cambered so that an upstream end ( 86 ) thereof is offset axially with respect to a downstream end ( 88 ) thereof.