To achieve direct drive or a 1:1 ratio, any two of the planetary gear components must be input at the same speed.

To achieve direct drive or a 1:1 ratio, any two of the planetary gear components must be input at the same speed.

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

Answer: (A)

Direct drive in a planetary gear set happens when there is no relative motion between two of the components, so the input is transmitted to the output at the same speed. In a planetary arrangement—the sun gear, the planet carrier, and the ring gear—the gearing effect comes from the relative motion between these parts. If two components rotate together at the same speed, they effectively act as a single unit, removing the gear reduction or multiplication between input and output. The remaining component then carries the output without any change in speed, giving a 1:1 ratio. So, the statement that two of the planetary components must be input at the same speed to achieve direct drive captures that idea: synchronization eliminates the gearing action and yields equal input and output speeds. If the speeds aren’t matched, the train will produce some non-1:1 ratio depending on which component is driven and which is held.

Direct drive in a planetary gear set happens when there is no relative motion between two of the components, so the input is transmitted to the output at the same speed. In a planetary arrangement—the sun gear, the planet carrier, and the ring gear—the gearing effect comes from the relative motion between these parts. If two components rotate together at the same speed, they effectively act as a single unit, removing the gear reduction or multiplication between input and output. The remaining component then carries the output without any change in speed, giving a 1:1 ratio.

So, the statement that two of the planetary components must be input at the same speed to achieve direct drive captures that idea: synchronization eliminates the gearing action and yields equal input and output speeds. If the speeds aren’t matched, the train will produce some non-1:1 ratio depending on which component is driven and which is held.