What does "gear ratio" refer to in the context of automatic transmissions?

In automatic transmissions, "gear ratio" refers to the relationship between the number of teeth on the gears. This ratio is crucial because it determines how many times the input gear (often connected to the engine) must rotate in order for the output gear (which drives the wheels) to complete one full rotation.

A higher gear ratio means that the engine will have to spin more times for one rotation of the wheels, which can lead to greater torque at lower speeds, making the vehicle more powerful for acceleration. Conversely, a lower gear ratio can provide better fuel efficiency and higher speeds due to less engine rotation required for the wheels to turn.

Understanding gear ratios allows mechanics to analyze transmission performance, optimize vehicle acceleration, and manage power delivery. It’s a fundamental aspect of how automatic transmissions function and helps in the tuning and adjustment of the vehicle's performance characteristics.