Lego Gears
Read on gears in general if you are new to the subject.
Lego gear wheels have a number of teeth that is a multiple of 4 (with one exception). They are therefore in principle not good for the transmission of power, but they are good for transmission of information.
Lego constructions do not run for great lengths of time nor do they need to transmit a lot of power, so it is not really a problem that there are no pairs with mutually prime numbers of teeth.
On the other hand, if we want to construct certain robots or models of clocks we need numbers of teeth that allow the transmission of exact multiples, and so they are good in those areas of application.
See gear dimensions and gear meshing for further details.
Table of Lego Gears
The table below lists some common gears:
| name | teeth | factors | |
|---|---|---|---|
 | worm | 1 | — |
 | normal 8 | 8 | 2×2×2 |
 | double conical, flat conical | 12 | 2×2×3 |
 | flat conical | 14 | 2×7 |
 | normal 16, end of differential, clutch, loose | 16 | 2×2×2×2 |
 | double conical, flat conical | 20 | 2×2×5 |
 | normal 24, crown, end of differential, internal of turntable, friction | 24 | 2×2×2×3 |
 | end of differential | 28 | 2×2×7 |
 | double conical | 36 | 2×2×3×3 |
 | normal 40 | 40 | 2×2×2×5 |
| (no illustration) | external of turntable | 56 | 2×2×2×7 |
 | internal of hailfire droid ring | 168 | 2×2×2×3×7 |
 | rack | ∞ | — (any) |
The only gear wheel with a number of teeth that is not a multiple of 4 is the small flat conical wheel with 14 teeth (apart obviously from the worm).