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)

In a planetary gear set, how fast the ring gear turns relative to the carrier depends on which gear is driving and how the sun gear, ring gear, and carrier interact through the planet gears. If the carrier drives and the ring gear ends up turning a little more than once for every one turn of the carrier—specifically, one full ring rotation plus motion corresponding to the sun gear’s teeth—you’re seeing only a small extra rotation contributed by the sun gear. That means the ring gear is spinning faster than the carrier, but only just, which is the smallest amount of forward overdrive achievable in this arrangement. The other scenarios would produce a larger overdrive or even reverse motion, so this description matches the minimum forward overdrive state.

In a planetary gear set, how fast the ring gear turns relative to the carrier depends on which gear is driving and how the sun gear, ring gear, and carrier interact through the planet gears. If the carrier drives and the ring gear ends up turning a little more than once for every one turn of the carrier—specifically, one full ring rotation plus motion corresponding to the sun gear’s teeth—you’re seeing only a small extra rotation contributed by the sun gear. That means the ring gear is spinning faster than the carrier, but only just, which is the smallest amount of forward overdrive achievable in this arrangement. The other scenarios would produce a larger overdrive or even reverse motion, so this description matches the minimum forward overdrive state.