Monday, March 8, 2010

Orbital Gearbox with 5 Speeds and Reverse

Name of Model: Prototype of my orbital and sequential gearbox.5 speeds and reverse
Created by: Durian
Found at:
This doesn't really count as robotics (there goes my "robotics Monday" theme), but it's some interesting food for thought that I think appeals to the same sort of Technic and Mindstorms sensibilities. We now have proof that it's possible to build a fully-functional orbital gearbox. Building gearboxes (also known as transmissions - they're primarily used in vehicles as transmissions even though they're now widely seen outside of complete cars) is one of the classic projects of LEGO Technic building - we first saw a linear transmission in a kit in the 1970's, and there have been countless improvements on the linear transmission concept over the years as well. Gearbox enthusiasts tinker for hours to determine just how many gears can be crammed into various set-ups, and a number of styles of transmission have appeared over the years. There have even been attempts at building automatic gearboxes and continuously variable transmissions. Sariel has previously built a 2-speed orbital gearbox, but there's a big difference between making a 2-speed model and making one that contains a decent selection of gears. The main appeal of using an orbital gearbox is the ability to shift gears without worrying about gears gnashing together in a potentially part-damaging way, so more gears makes the set-up more valuable. It's not quite as clear how this one works (not all of us document our creations as well as Sariel does), but I believe you can figure it out after going through the photos. A clutch mechanism allows the gears to be shifted, and the reverse is achieved by using a 16-tooth gear that's not firm on the axle to reverse the 16-tooth output gear's speed. I suspect that there might be a slightly less bulky way of getting 6 gear ratios into an orbital gearbox, but I'm impressed with the ingenuity of this construction already - it's an excellent use of those belt wheels with 6 pin holes. Now if only we could get more builders thinking of ways to construct things with exciting angles - it unlocks all sorts of new possibilities.

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