In which condition does one complete rotation of the carrier drive the ring gear one complete turn plus the sun gear tooth count?

In which condition does one complete rotation of the carrier drive the ring gear one complete turn plus the sun gear tooth count?

• A. Maximum forward overdrive
• B. Minimum forward overdrive
• C. Reverse reduction
• D. Maximum forward reduction

Answer: (B)

The situation tests how planetary gear sets produce overdrive as the carrier turns. In this setup, the ring gear speed relative to the carrier is governed by how the sun gear and ring gear mesh together and whether the sun gear is contributing motion or held in a certain way. When the carrier completes one full turn, the ring gear ends up turning forward by exactly one full turn plus an amount tied to the sun gear’s teeth. That added amount is the smallest possible positive forward motion—the ring is moving forward, but only just more than one turn per carrier revolution. This is the minimum forward overdrive.

The other conditions involve larger forward speeds (maximum forward overdrive), opposite-direction motion (reverse reduction), or forward motion that’s less than this minimal amount (maximum forward reduction), so they don’t match the described relation.