In a nutshell, an automatic transmission is a transmission system that changes gears for you to prevent you from either stalling or redlining your engine. If you are the type of driver that gets flustered when you have a lot of things to concentrate on all at once, an automatic transmission takes a lot of the hassle out of driving.

An automatic transmission uses a number of components to get the optimum amount of power from the engine to the wheels. An automatic transmission incorporates a torque converter, which takes the place of a clutch; a complex planetary gearing system that provides all the different ratios, and a hydraulic system of valves that regulate how the gears interact with each other. The fluid inside an automatic transmission system (known as automatic transmission fluid or ATF) is used not only for the hydraulics, but also as a lubricant and to prevent corrosion of the parts

In a car with auto transmission, the driver still has some measure of control. A selector takes the place of a regular gearstick. This allows the driver to select a number of options: Park, Reverse, Drive, Neutral and up to three low gears. While it is obvious when a driver would set the automatic transmission to Park or Reverse, it is important to know when to use the other functions in an automatic transmission. Drive is the most common setting. This is the basic one that takes over all the gear changes for the driver in most conditions. The lower ratios are used to keep the transmission to the lower gears, and are important for when a driver needs to get maximum power. The most common situations when an automatic transmission will be set to 1, 2 or 3 are in hill driving or when towing. Neutral allows the engine to run while the car is stationary, much like the neutral gear in a manual transmission. It is important to set the automatic transmission to neutral when waiting at a red light. While it is possible to keep the automatic transmission in Drive and the brake applied – which certainly allows for quick takeoff when the light changes – this can cause excessive wear to the automatic transmission system. And a damaged automatic transmission system is not cheap to repair.

The advantages of an automatic transmission system are hassle-free driving with little or no risk of stalling. The downside of an automatic transmission is a reduction in fuel efficiency and slightly less control over the engine’s power and torque. Performance figures for vehicles with automatic transmissions tend lag slightly behind those of manual versions of the same engine, particularly in the 0–100 km/hr figures. However, with modern technology and design, the gap between manual and automatic transmissions is greatly reduced from what it was when automatic transmissions were first introduced.

The first production cars to feature automatic transmission were the 1940s Oldsmobiles.
We hope that helps answer the question ‘What is What is an Automatic Transmission?’!

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