Fluid transmitting system with lock-up clutch

A fluid transmitting system with a lock-up clutch, comprising a pump impeller, a turbine runner which defines a circulation circuit between the turbine runner and the pump impeller, a side cover which is connected to the pump impeller and which defines a clutch chamber between the side cover and an outer side of the turbine runner to communicate with an outer peripheral portion of the circulation circuit, and the lock-up clutch disposed in the clutch chamber and capable of coupling the side cover and the turbine runner directly to each other,

• the lock-up clutch being comprised of a clutch piston axially movably connected to the turbine runner to divide the clutch chamber into an inner oil chamber section on the side of the turbine runner and an outer oil chamber section on the side of the side cover, a lock-up control means adapted to generate a difference in pressure between the inner oil chamber section and the outer oil chamber section to advance and retract the clutch piston to and from the side cover, a friction engaging means adapted to bring the clutch piston and the side cover into friction engagement with each other when the clutch piston is pushed against the side cover, and a resilient member disposed between the clutch piston and the turbine runner to bias the clutch piston toward the side cover,
• wherein the resilient member is mounted to piston hub of the clutch piston axially slidably carried on a turbine hub of the turbine runner so that the deformation attitude of the resilient member is changed freely, and
• wherein the turbine runner comprises a shell-mounting flange provided at an outer periphery of the turbine hub, and an annular recess for receiving a tip end of the piston hub is formed in one side of the shell-mounting flange, and a limiting means is provided by abutment between a bottom surface of the annular recess and a tip end face of the piston hub for limiting the amount of movement of the clutch piston toward the turbine runner to a constant value thereby preventing an excessive resilient deformation of the resilient member, when the clutch piston is urged toward the turbine runner while producing a deformation of the resilient member thereby bringing the friction engaging means into a non-operative state.