In a planetary gear set where the carrier is the input component, the sun gear is the held component, and the ring gear is the output component, the result is minimum forward reduction. Who is correct?

In a planetary gear set where the carrier is the input component, the sun gear is the held component, and the ring gear is the output component, the result is minimum forward reduction. Who is correct?

• A. Technician A
• B. Technician B
• C. Both Technician A and Technician B
• D. Neither Technician A nor Technician B

Answer: (B)

The key idea is how a planetary gear set changes speed based on which gear is held and which is driven. With the sun gear held stationary and the carrier (the planet carrier) driven, the planets rotate around the fixed sun and push the ring gear to rotate as the output. In this arrangement, the ring’s motion is constrained by the fixed sun and the carrier’s drive, so the ring ends up turning forward but at the slowest possible speed relative to the carrier for this particular hold/drive configuration. In other words, this setup yields the smallest forward reduction among the common hold/input/output combinations. That’s why the conclusion associated with Technician B is correct.

The key idea is how a planetary gear set changes speed based on which gear is held and which is driven. With the sun gear held stationary and the carrier (the planet carrier) driven, the planets rotate around the fixed sun and push the ring gear to rotate as the output. In this arrangement, the ring’s motion is constrained by the fixed sun and the carrier’s drive, so the ring ends up turning forward but at the slowest possible speed relative to the carrier for this particular hold/drive configuration. In other words, this setup yields the smallest forward reduction among the common hold/input/output combinations. That’s why the conclusion associated with Technician B is correct.