#$2$

Planetary Gear Train System with an Idler Planet Gear

$9-$ Arm

$7,6,3-$Planet Gears $6$ rolls internally with $54$

$6$ rolls externally with $7$

$3$ rolls externally with $2$

$3$ rolls internally with $54$

$7$ rolls externally with $8$ and $6$

$2$ is the Input, $9$ is the Output

Compute the gear ratio $R=\frac{{}_2}{}{}_9$

Planetary Gear Train System with an Idler Planet Gear