What is kick down used for on automatic transmissions?

Answer 1

For quicker acceleration when needed, such as for passing.

A kickdown lever (or cable) comes into play when you depress the accelerator pedal while accelerating fairly powerfully. Usually while passing someone or climbing a steep hill. The idea behind the kickdown is to place the transmission into a lower gear without having to manually place the transmission shifter into a lower gear.

The "lower" gear allows the engine to "rev up" faster which delivers more power by causing the engine to obtain more revolutions per rotation of the tires which produces a noticeable increase in power.

To test that your kickdown is operating correctly Merely floor the gas pedal at a road speed (45 mph or so) and you should easily feel and hear the engine power (revolutions) increase. Do this safely please. NOT on wet pavement or high traffic conditions.

Manual transmissions do not have kickdowns - You must manually place the transmission into a lower gear to get the same effect of more power and revolutions per minute.