pic: Planetary wheel (cutaway)

[Tristan Lall]

Originally Posted by 11Ed71

Cutaway view of an idea I had that I fleshed out into a design. It will probably never get built, but here's the first revision of the design. All parts are stock parts available from McMaster or SDPSI or are easily machinable on a CNC mill. Opinions are welcome, but if all you're going to say is that it won't work, I don't need to hear that.
Side loads may be an issue, but since the whole thing is riding on roller bearings, I don't think it will be.
Completed, the module runs directly off a CIM, and is bolted to a frame member on both sides (this mounting plate isn't visible here to make the gearing visible), with the wheel part (everything seen here) spinning at a 16:128 reduction. (Stationary planets, driven ring as output/wheel surface.) The wheel surface would be sheet metal with some kind of rubber tread.

How are you supporting the outer ring with respect to the planet gears and planet carrier? If your outer ring can wobble about the central axis, you're probably going to encounter a lot of uneven tooth wear. You definitely can't rely upon the tooth mesh to support the weight of the robot.

Also, is the 16 tooth gear hardened steel? Because it probably ought to be. (What's the SDP/SI part number?)