As you can see in the picture, the free turbine still gets the same exhaust gas that the main turbine gets.
- How can it exactly spin freely from the main turbine?
- How can the free shaft even stay stationary while the main turbine is spinning at high rpm even though it is still exposed to the same exact exhaust gas flow which makes the main turbine rotate?
- Why does the exhaust gas also not rotate the free shaft?
- Does the free shaft have a clutch attached to it or something that disconnects it from the driven wheel or the propeller so that wheel or propeller can stay stationary even if engine itself is spinning at high rpm?
I also read that gas turbine engines can act as a clutch or a fluid coupling exactly because of the fact that free shaft can operate freely from the main turbine. Chrysler, for example, in their turbine car removed the torque converter from the TorqueFlite automatic transmission that was attached to the gas turbine because gas turbine itself could act as the torque converter and therefore didn't need a separate torque converter to disconnect the engine from the output shaft.
How exactly is this "free spinning shaft" action accomplished?