In a simple gear train, which gear is the driving gear and how is gear ratio determined?

• A. The pinion is the driving gear; gear ratio is determined by tooth counts.
• B. The gear wheel is the driving gear; the pinion is driven; gear ratio is determined by diameter.
• C. The pinion and gear wheel rotate in the same direction; gear ratio is a constant 1.
• D. The pinion is the driven gear; gear ratio is determined by length of teeth.

Answer: (A)