Tips for Lego Gearing

Here are 2 tips that I have for building Lego gear-trains.

Tip 1: Reinforcing Gears

Gears often crack when the gear-train is under stress. Cracking will severely reduce and limit the amount of power transferred and will potentially damage the gears. To overcome this problem, I recommend adding a second mounting beam to the gears, such that the gears are sandwiched between the two beams.

Common Construction:                                                      My Construction:
This method works for almost all types of straight gear trains, even compound ones. It completely eliminates cracking. This is very useful in high-stress applications, for example, sumo bots, cranes, lifting devices, etc.


Tip 2: Dealing with 8-tooth Spur Gears

A problem I observed when building gear trains with 8-tooth gears was their tendency to slip slightly out of alignment.

Perfect Alignment:                                                             Slightly out of Alignment:

As you can see, the gear slips out of alignment slightly, the edge of the gear digging into the mounting hole. This would increase the friction in the gear train and would also limit the amount of stress it can handle. A method I came up with was to use half-bearings as washers, to separate the gear from the mounting beam.

Common Construction:                                                     My Construction:
You could apply the method in Tip 1 to eliminate gear cracking.