The sprag is a one-way, mechanical clutch
inside the stator. It locks the stator in place while the converter is in
stall mode. It also allows the stator to spin with the rest of the converter
after the turbine speed nears the pump speed. This makes for a more
efficient and less restrictive fluid flow.
Impeller Pump is a centrifugal pump which attaches to the transmission side. It has a
series of fins which drive the fluid into the turbine. The size of the torque converter and pump and
the number and shape of the fins all affect the characteristics of the
converter. It is important that the fins of the impeller pump are adequately
reinforced against fatigue and the outside housing does not distort under
Fin brazing (furnace or spot brazing)
enhances the strength of the fins. The housing and fins
should act as one unit. By reducing the amount of flex, fins are less likely
to break under pressure. The more rigid the fins stay while under pressure,
the more consistent the behavior of the torque converter.
Needle bearings are important because they
help the torque converter withstand more pressure and provide less drag
inside the converter.