Toyota Torque Converter Operations and Diagnosis

TORQUE CONVERTER BASICS (Using a 2003 Camry/Solara as our example)
Mounted on the input side of the transmission, the torque converter is connected to a drive plate (or flex plate) that is connected to the rear of the crankshaft. The torque converter (which is filled with automatic transmission fluid) multiplies torque generated by the engine and serves as an automatic clutch that transmits engine torque to the transmission, absorbs torsional vibration of the engine and drivetrain, and drives the oil pump of the hydraulic control system.
The torque converter’s main components include the pump impeller, the turbine runner and the stator. When the impeller — which is inte- grated with the torque converter case — is driven by the engine crankshaft, the fluid in the impeller rotates within it. As impeller speed increases, centrifugal force causes the fluid to flow outward toward the turbine. The turbine is located inside the case but not connected to the case.
The transmission input shaft is attached by splines to the turbine hub. A series of cupped vanes are attached to the turbine. The curvature of the vanes is opposite from the impeller vanes. When the fluid is thrust from the impeller, it is captured in the turbine’s cupped vanes. This transfers torque to the transmission input shaft, turning it in the same direction as the engine crankshaft.
The stator is located between the impeller and the turbine. The stator vanes catch fluid as it leaves the turbine runner, and redirects the fluid so that it strikes the rear of the impeller vanes. This provides added boost to the impeller and translates into as much as 30% to 50% added torque. The one-way clutch allows the stator to rotate in the same direction as the engine crankshaft. If the stator attempts to rotate in the opposite direction, the one-way clutch locks the stator to prevent rotation. The stator is rotated or locked, depending on the direction from which the fluid strikes the vanes.

pdf source: http://www.toyotapartsandservice.com/pub/pdf/TechCenterLibrary/ToyotaStarServiceNews/2006/2006_TSSN_Spring.pdf