How many planetary gear sets are used in the six-speed World Transmission?

How many planetary gear sets are used in the six-speed World Transmission?

• A. Three planetary gear sets
• B. Four planetary gear sets
• C. Five planetary gear sets
• D. Six planetary gear sets

Answer: (A)

Planetary gear sets multiply torque, and when you stack them in a train and control which elements are held or driven with clutches, you can create many different overall gear ratios. The six-speed World Transmission uses a compound arrangement of three planetary gear sets. By selecting different combinations of locked elements (sun, ring, or carrier) for each gear, the system turns into six distinct forward speeds. The extra set provides the additional ratio steps needed to reach six gears while keeping the design compact and efficient. With fewer than three sets, you wouldn’t have enough combinations to realize six distinct forward speeds in a practical automatic transmission, so three is the chosen arrangement.

Planetary gear sets multiply torque, and when you stack them in a train and control which elements are held or driven with clutches, you can create many different overall gear ratios. The six-speed World Transmission uses a compound arrangement of three planetary gear sets. By selecting different combinations of locked elements (sun, ring, or carrier) for each gear, the system turns into six distinct forward speeds. The extra set provides the additional ratio steps needed to reach six gears while keeping the design compact and efficient. With fewer than three sets, you wouldn’t have enough combinations to realize six distinct forward speeds in a practical automatic transmission, so three is the chosen arrangement.