Difference between Torque converter, AMT, CVT and DCT

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Difference between Torque converter, AMT, CVT and DCT

What are the differences between different 'automatic cars' from different manufacturers? Which is the best self shifting gearbox? From which manufacturer?

There are four major categories of Automatic transmissions.

1. Torque converter Autos

2. AMT - Automatic manual transmission

3. CVT - Continuous Variable Transmission

4. DCT - Dual Clutch Transmission

1. Torque Converter – This is basically a donut shaped metal with fluid sealed into it with a turbine on one side (flywheel) and a pump on the other side. Separating the two side, we have a finned stator.

The turbine is connected to the flywheel so it turns at the same RPM as the engine. The stator acts as a clutch that works by changing the direction of the fluid coming from the turbine. The pump drives the wheels.

2. AMT - Automatic Manual Transmission is a clutch-based gearbox where gear changes and actuation is done without the intervention of the driver. AMT are more often than not referred to as just Automatic Transmission. It's popular with Mazdas, BMWs and Hyundai

AMTs have a clutch but lack a clutch pedal (eating the cake and having it). The actuation (kanyanga clutch, achilia) is done using either an electric actuator or an electrohydraulic actuator controlled by the ECM.

CVT - Continuous Variable Transmission is a single speed automatic gearbox. This gb is made up of 2 cone pulleys with a V-shaped driving belt connecting them. One of the pulleys is connected to the engine and the other one is connected to the wheels (through whatever).

When you accelerate, the engine speed increases and so does the cone speed. The driving cone adjusts to the speed to ensure the v-shaped belt is always under tension. This makes the CVT shifts seamlessly through an endless range of effective gear ratios as you drive.

4. DCT - Dual Clutch transmission is an AMT with two clutches instead of one. One clutch controls the odd gears while the other clutch operates the even gears. This means that when driving at gear 1, Gear 2 is ready.

Hence you can shift without interrupting the power flow from the engine to the transmission.The magic of the dual-clutch transmission is that it can change from one gear to another very quickly.