What device is used to convert engine power to the drive train in an automatic transmission?

The torque converter is a crucial component in an automatic transmission system, serving to connect the engine's output to the drivetrain while also enabling the automatic transmission's unique function of providing smooth acceleration and allowing the vehicle to come to a stop without stalling the engine.

The torque converter operates using fluid dynamics; it utilizes a fluid coupling to transmit engine power to the transmission. When the engine is running, the torque converter uses a series of turbines and a stator to convert engine power into hydraulic pressure, which then drives the transmission. This allows the vehicle to start moving smoothly even from a complete stop and provides the necessary multiplication of torque to assist in acceleration.

In contrast, the flywheel is primarily used to maintain consistent engine speed and smooth out power delivery from the engine, but it does not facilitate the dynamic connection between the engine and the transmission in the same way as the torque converter. The gearbox is a broader term that refers to the entire system of gears within the transmission, enabling various gear ratios, but does not convert power itself. The clutch is found in manual transmissions and is used to engage and disengage the engine from the drivetrain, but it does not serve the same purpose as the torque converter in an automatic transmission, where continual engagement without driver input