Torque Converter

     A torque converter consists of four basic parts：the outer housing，an impeller or apump, a turbine and a stator. These parts are shown in Fig. 9. 6.

    With the engine idling，the impeller spins slowly. Only a small amount of oil isthrown into the stator and turbine.  Not enough force is developed inside the torqueconverter to spin the turbine. The car remains stationary with the transmission in gear.

    During engine acceleration, the engine crankshaft, converter housing，and impellerare driven by centrifugal force. This makes the turbine begin to turn. As a result, thetransmission input shaft and vehicle start to move, but with some slippage.

    At cruising speeds，the impeller and turbine spin at almost the same speed, with verylittle slippage.