The turbine in a torque converter is similar in construction to the impeller. That is, the turbine is a round part with vanes, or blades. This construction makes sense when you consider that the turbine catches the fluid thrown off by the impeller.

As the fluid is thrown off the impeller, the blades on the turbine capture it, forcing the fluid to the center of the turbine. This force turns the turbine before the fluid flows back through the center of the turbine to the impeller.

The force of the fluid striking the turbine blades is related to engine speed. The faster the crankshaft rotates, the more force the fluid transfers from the impeller to the turbine. When the engine is idling, the fluid does not have enough force to turn the turbine against the holding ability of the brakes. The fluid is merely circulated from the impeller to the turbine, and back again.

The fluid leaves the impeller in a clockwise direction and returns from the turbine in a counterclockwise direction.