What is a planetary gear, and how does it work?

Planetary gear is a mechanical device composed of a central sun gear, a number of planetary gears and a ring gear. Just like the planets revolve around the sun, so planetary gears get their name. The planet gears revolve around the sun gear and mesh with the ring gear, creating a unique type of gear system that provides a variety of gear ratios and rotational motion.

How does the planetary gear work?

The previous article introduced that the planetary gear system has three main components: the sun gear, the planetary gears and the ring gear. In this type of system, the sun gear is a central gear that rotates around a fixed axis. The planet gears are the smaller gears that revolve around the sun gear, and the ring gear is the larger gear that circles the planet gears.

When the sun gear rotates, the planet gears rotate around it, causing the ring gear to rotate as well. The direction of rotation of the ring gear will depend on the direction of rotation of the sun gear and the relative sizes of the sun and ring gears. If the sun gear is larger than the ring gear, the ring gear will rotate in the opposite direction to the sun gear. If the sun gear is smaller than the ring gear, the ring gear will rotate in the same direction as the sun gear. The gear ratio of a planetary gear system can be calculated by dividing the number of teeth on the ring gear by the number of teeth on the sun gear. For example, if the ring gear has 60 teeth and the sun gear has 20 teeth, the gear ratio is 3:1. This means that for every revolution of the sun gear, the ring gear will rotate 3 times.

Conclusion

Planetary gear systems come in many configurations, such as systems with multiple sun gears, multiple ring gears, and multiple planet gears. These various configurations allow for a wide range of gear ratios and rotational motions, making planetary gears useful components in many different types of mechanical systems.