Straight lines

Spotted earlier and pocketed to share.
And I’m ashamed to say that this took me some time to work out, despite the helpful title:

All the bearings are moving in a straight line!!!

I didn’t sleep well last night, ok? Everything is taking longer than it should do today.

Link

Anyway, surely a better way of putting it would be:

Each of the bearings is moving in a straight line!!!

Either way, it’s strangely mesmerising.
I am strangely mesmerised.