Planetary Train

Fig 1: Identifying Planetary Train Components

Courtesy of VOLVO CARS CORPORATION

The planetary train is used to reduce the rotational speed of the pinion gear in relation to the speed of the armature and to increase the torque of the pinion.

The planetary train consists of: 

1. Pinion shaft with splines
2. Ring gear (fixed section)
3. Planetary gear (connected to the pinion shaft)
4. Sun gear (connected to the rotor)
5. Armature
6. Commutator