There is no clutch pedal in an automatic transmission car.
There is no gear shift in an automatic transmission car. Once you put the transmission into drive, everything else is automatic.
Both the automatic transmission and a manual transmission accomplish exactly the same thing, but they do it in totally different ways. It turns out that the way an automatic transmission does it is absolutely amazing.
The key to the modern automatic transmission is the torque converter. It takes the place of a clutch in a manual transmission.
A direct descendant of an earlier component called a fluid coupling, the torque converter offers the advantage of multiplying the turning power provided by the engine. It is connected to the motor by means of a metal rod known as the transmission shaft Inside the torque converter are several components that help multiply the power. These are the impeller or pump, the turbine, and the stator or guide wheel.
A torque converter is like a giant doughnut. The impeller and the turbine  face one another inside the round metal casing. The impeller is on the engine side, the turbine on the tranny side. Both of these components have blades that catch the transmission fluid and cause them to spin.