How Does an Automatic Transmission Work?

If the driver’s experience with automatics and manuals is quite different, what’s happening under the hood is largely the same. Both types work to allow your engine to operate within a narrow range of speeds while allowing the car itself to experience numerous output speeds.

In both types of cars, gears are used to leverage the engine’s torque and allow that engine to keep whirring along at a reasonable speed. The end result is that drivers can operate their cars at varying speeds and accelerations without having to worry about the engine burning up.

But how do automatics and manuals actually differ on a technical level?

The big difference is that a manual will lock and unlock different gears to produce needed gear ratios. With an automatic, the same set of gears produces all the necessary gear ratios—thus, no need for gear shifting.

The Key Components

To make all of this happen, the automatic relies on a few key components. Some of these components to know about are:

• The planetary gear sets, which provide all forward and reverse gear sets.
• The hydraulic system, which uses a special transmission fluid to control the planetary gear sets.
• The torque converter, which basically serves as the clutch, letting a gear stop while the engine keeps running.
• The governor and the modulator, which determine speed and throttle and signal for gear shifts when needed.