How Automatic Transmissions Work

Summary

Look inside a car's automatic gearbox. When you pull away from a stop, the engine spins a small gear that meshes with a much larger one beside it.

Chapters

1. Look inside a car's automatic gearbox. (0s)
2. As your speed climbs, sensors read (19s)

Transcript

Look inside a car's automatic gearbox. When you pull away from a stop, the engine spins a small gear that meshes with a much larger one beside it. This tall ratio multiplies torque, trading away top speed for the raw muscle needed to get a heavy car rolling from rest. Watch the power flow along the meshing teeth, turning slowly but with tremendous force. As your speed climbs, sensors read how fast the wheels are turning, and hydraulic clutches quietly swap the power pathway onto smaller, faster gears. Now a single turn of the engine spins the wheels much further with each rotation. So at cruising speed the engine can finally relax, dropping its revs and sipping fuel as you glide smoothly and quietly down the open highway.