Torque Converter FAQ

How a torque converter works:
Torque converters are used in modern automatic transmissions to connect and disconnect the transmission from the engine using a fluid coupling and to multiply engine torque. The torque converter can be seen as a pump because of its ability to move fluid. In manual transmissions a clutch is used to connect and disconnect the engine from the transmission when the car has come to a stop.

The torque converter consists of three main parts:

1) The stator or one way clutch (which redirects oil from the impeller to the turbine). Most stators have splines that connect with the input shaft. The stator was introduced into torque converters in the sixties when huge engines were no longer available. Car engineers had to find a way to get the most power transferred to the wheels with smaller motors.

2) An impeller which is directly connected with the automobiles engine.

3) A turbine which oil gets redirected from to the impeller. The impeller is attached to the torque converter cover while the turbine is free to turn.

To see how a simple fluid coupling works place a fan that is turned on in front of a fan that is tuned off. The fan that is on will cause the fan that is off to rotate. A modern torque converter works this way except it has a sttor in the middle of the two "fans" This is exactly what happens in a fluid coupling, except the impeller is driven by the engine which get oil redirected to it from the turbine by using the stator.

Lockup

Some converters include a lockup clutch which improves efficiency by making the impeller turn at almost the same speed as the engine. The downside of a lockup torque converter is that it makes for a much rougher engagement.

Stall Speed

Stall speed is when the ithe turbine has stopped turning so the stator is no longer needed to redirect fluid. When the turbine is no longer rotating the transmission shifts A higher stall speed would mean that the transmission would shift at a higher rpm resulting in major benefits, due to the fact that the transmission will shift very high in the RPMs while racing. A disadvantage of a high stall speed is the loss in gas mileage. The car runs at higher RPMs before shifting.

--STEVE S
I would like to thank WhiteStang99 and Brent (better late than never, huh brent?) for making this how to better!