How Do Gas Pumps Know When to Stop?

If you've ever put gas in a car, you'll know that the pump magically knows when to stop spewing fuel into the tank. That's super useful, and safe too. But how does it know when to stop?


Is it witchcraft? Psychic powers? Clever guesswork? Or, you know, some simple but incredibly smart engineering? Watch this video and find out! [YouTube]



So is this complicated mechanism what I should blame for the gas dribbles on my car when I pull the nozzle out?