Automatic and manual car

[ATOB2]

What's the mechanical difference between an automatic and a gear car?

[sabrinah]

In a manual car, the transmission locks and unlocks different sets of gears to the output shaft to get the different ratios, first for moving off, fourth for cruising etc. Whereas in an automatic car all the different ratios are produced when they are needed by the same set of gears, using something called a planetary gearset.