Question

the rule of reduction states _________.
when there is an input and no member held or a member held and no input
when the sun gear is the input and the annulus is held, the carrier is the output, and is in gear reduction
when any two members of the gearset are the input or driven in the same direction
when the planetary pinion carrier is held and either the sun or annulus gears are the input

Explanation:

In planetary gear systems, the gear reduction rule is typically when the sun gear is the input, the annulus (ring gear) is held, and the carrier is the output. This configuration results in gear reduction as the carrier speed is lower than the sun gear speed (due to the mechanical advantage from the gear sizes and meshing).

• Option C1: If there's an input and no member held (free - wheeling) or a member held and no input, it doesn't follow the standard reduction principle.
• Option C3: When two members are input or driven in the same direction, it's more related to direct - drive or other non - reduction operations.
• Option C4: When the carrier is held, it's a different configuration (usually for reverse or other non - reduction functions).

Answer:

When the sun gear is the input and the annulus is held, the carrier is the output, and is in gear reduction.