Retaining Things?

[TheHolyHades1]

Hello,

In recently thinking about designs for gearboxes and drives, I am led to wonder how gears are held in place in these designs. I know that for a cylindrical shaft, keys can be used to keep gears/hubs from rotating, and that they have enough friction to prevent it from sliding on the rod. Alternatively, retaining rings can be used, as on CIM motors (is that how it's done on the banebots RS motors, too?)

The obvious advantage of hex shafts is that you don't need to use a key, but that leaves the question of retaining things on the shaft. I'm pretty sure retaining clips can be used if there's a slot machined into the shaft, but I'm curious if there's any other ways of doing it. I know people also use shaft collars and set screws, but we've had bad experiences with each of those things falling off ...

Thanks,
Hades