Question about the operation of a bearing

[titiyador]

Hello or rather good evening,

A question that may seem silly and that I ask myself is ... how does a bearing work?

I'm not talking about the bearings that make it up, but mainly, how to mount one, for example on the following video:
https://www.youtube.com/watch?v=Nudo9MJBrUg

we see a vertical pumping wind turbine. There are bearings for each axis, which makes sense. But I do not understand how an axis, which "enters" into the bearing, does not come out below (see in the video at 0'48 for example). I don't think there is a set screw, as it will create too much friction. Nor that there is a pedestal, for the same reason.
Could it be the axis in itself which would be strangled in the bearing?

I have a little trouble understanding and I have recently become interested in this type of wind turbine that I would like to achieve with the same reduction system (mounted in the other direction than that visible in the video) to rotate a discoid axial alternator with permanent magnets from 100 to 200w.

Thank you for your answers! Tim.

[Ahmed]

To hold an axis in place, all you need is a simple ring or a shoulder ...

[titiyador]

Well it creates friction, right?

[Ahmed]

Yes, but if it is only the weight of the axis, it remains really minimal.

When the axial loads are higher, there are ball bearings with special bearings and, better, tapered bearings or even thrust ball bearings, depending on what we are looking for.

In your case, if you consider that direct friction would be undesirable, a light thrust bearing could be suitable *; however if your axis passes through the bottom bracket, it already has two bearings with opposing seats which accept a moderate axial stress.

* As the first image of this link.