Innovations in Driving: The Automatic Transmission

How a new gear-shifting system made cars easy to drive and harder to fix

Automatic Transmission

vestman via flickr.

Have you ever looked at a diagram of an automatic transmission?

If not, check this out:

Diagram of an Automatic Transmission

I defy anyone who isn't a mechanical engineer or who doesn't work in the transmission industry to make sense of this schematic.

There are, of course, plenty of things about cars that are hard to understand. Wiring looms, for example. The innards of limited-slip differentials. How the [with a bicycle](http://www.popsci.com/cars/article/2002-04/speed-record

Pontiac Aztec ever made it into production. But for pure, unalloyed WTF-ness, nothing comes close to the automatic transmission. A conventional manual, or sliding-gear, transmission is a reasonably straightforward piece of technology. As

continuously variable transmissions, now popular on contemporary econoboxes, date back to this era. During the 1930s, Cotal (in France) and Wilson (in England) developed what were known as pre-selector gearboxes, which still required drivers to change gears but which made the process almost foolproof. Meanwhile, here in the States, General Motors and Reo introduced semi-automatic transmissions that freed drivers from the need to use the clutch. Even as GM was selling – though not very well – this Automatic Safety Transmission, its engineers were working furiously on what would become the world's first genuine automatic transmission. Developed under the direction of Earl Thompson, who also invented the cone-style synchromesh transmission, the Hydra-Matic