In a planetary gear set, the minimum number of tooth sets transmitting torque is which value?

In a planetary gear set, the minimum number of tooth sets transmitting torque is which value?

• A. One
• B. Three
• C. Two
• D. Five

Answer: (B)

In a planetary gear set, power has to move through multiple gear contacts while there’s a path for reaction and for delivering the output torque. The sun gear drives a planet gear through a sun-planet mesh. That’s one tooth set transmitting torque. Those planet gears also mesh with the ring gear, creating a second torque-transmitting contact. The torque carried by the planet gears is then transferred to the carrier, which supports the planets and serves as the output; this connection provides a third transmission path from the gears to the output. Because you need these multiple, distinct paths to make the system work and provide the necessary reaction, the minimum number of tooth sets transmitting torque is three. If you tried with fewer, you’d lack a proper reaction or output path and the system wouldn’t function as a true planetary arrangement.

In a planetary gear set, power has to move through multiple gear contacts while there’s a path for reaction and for delivering the output torque. The sun gear drives a planet gear through a sun-planet mesh. That’s one tooth set transmitting torque. Those planet gears also mesh with the ring gear, creating a second torque-transmitting contact. The torque carried by the planet gears is then transferred to the carrier, which supports the planets and serves as the output; this connection provides a third transmission path from the gears to the output.

Because you need these multiple, distinct paths to make the system work and provide the necessary reaction, the minimum number of tooth sets transmitting torque is three. If you tried with fewer, you’d lack a proper reaction or output path and the system wouldn’t function as a true planetary arrangement.