Lego Technic Planetary Hub

A Planetary Hub, or gearbox works in the same manner as a regular gearbox, either increasing or decreasing torque and speed. In my video above, I show how to build your own Planetary Hub with Technics. This webpage can give you a better understanding of the principles of a Planetary Hub. Four key components are needed in order to create a proper Planetary gear set (Fig 1.). The Sun gear is usually the input gear in a Planetary setup, but it can also be the output gear. The Sun gear turns the Pinions, in the image below there are only three Pinions, but more Pinions can be added to cope with 

Fig 1.

stress, provided they don't mesh with one another. The Carrier functions as a holder of the Pinions, to keep them evenly spaced, the Carrier is usually what is mounted to the chassis of a vehicle. The Ring gear can be considered the most important part of a Planetary setup as the Ring gear is what’s mounted to a wheel, or any other rotary device. To achieve different gear ratios in a Planetary setup one would change any of the following three: the tooth count on the Sun gear, the tooth count on the Pinions, and finally the tooth count of the Ring gear. In my Planetary setup I used a 24-tooth Ring gear from the old style stud less turntable, when an 8-tooth gear is used as a Sun gear, with two 8-tooth gears used as Pinions, provides a 1:4 ratio. The Black part of the turntable in my Planetary setup doesn't rotate, the grey part of the turntable does turn as the Pinion gears are meshed with the inner gear ring of the grey part. thats all for now, remember if you can dream it, you can build it.