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­If you have ever driven a car with an automatic transmission, then you know that there are two big differences between an automatic transmission and a manu­al transmission:

  • 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 (plus its torque converter) and a manual transmission (with­ its clutch) 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!

Transmission Image Gallery

6L50 transmission
Bill Pugliano/Getty Images
The 6L50 transmission is a Hydra-Matic six-speed rear and all-wheel drive automatic transmission produced by GM. See more transmission pictures.

In this article, we'll work our way through an automatic transmission. We'll start with the key to the whole system: planetary gearsets. Then we'll see how the transmission is put together, learn how the controls work and discuss some of the intricacies involved in controlling a transmission.