No one knows who invented the planetary gearbox, but it has been in use since the 15th century.Planetary Gearboxes is an old mechanics fundamental that is still being used for new eading innovative technology like 3D printing, and new methods of transport.
Planetary gearbox consist of an internal toothed ring gear to which are set 3 planets mounted on the planet carrier engaging also with the sun gear and reduced output speed is taken through planet carrier and ring gear is remain stationary.Output shaft maintaining the same direction of rotation as Input.

How bearing behavior in a planetary gear :

Salient Features of Planetary Gearbox:

High reduction ratios, high-efficiency long Life, space-saving compactness, higher overload capacity, reliable service, greater stability, compact and co-Axial sturdy,no-self locking property,load distribution among planetary gears.

Needle roller bearing is used in the planetary gear mechanism used in the advance/retraction switching mechanism of the CVT.
While a large centrifugal force is generated in the planetary gear during high-speed operation an extended service life and a small torque are realized through adoption of the special heat treatment shaft and cage and rollers of a strong retainer.

TBB Needle roller bearing have the features of low cross section and high carrying capacity.
In the application where less space is available, alignment needle roller bearing offer a compact solution, and owing to their large number of rollers, alignment needle roller bearing have a high load carrying capacity.