What does the term "gear ratio" define?

The term "gear ratio" defines the relationship between input speed and output speed in a gearbox. Gear ratios indicate how many revolutions a driver gear needs to make to rotate the driven gear once. This relationship helps determine the mechanical advantage provided by the gears, affecting both speed and torque in the system.

For instance, a higher gear ratio means that the driven gear turns fewer times than the driver gear, resulting in increased torque but decreased speed. Conversely, a lower gear ratio allows for higher speed but less torque. Understanding gear ratios is crucial in applications ranging from automotive transmissions to industrial machinery, as they help optimize performance for specific tasks.

The other options relate to different aspects of gears. The difference in diameter between gear components pertains more to physical size rather than their operational performance. The amount of torque transferred by a gear is a result of the gear ratio but does not define it directly. Meanwhile, the number of teeth on a gear contributes to determining the gear ratio but is not the definition of it.