This is, for one thing, a very poor photo.
It is a good picture of a mechanical brake system but sadly, it is a very poor photo.
It's very hard to see the rod that pushes down on the wedge that seperates the rollers that roll down and seperate the shoes that apply presure to the drum that slows the wheel that stops the tire, therefore imobilizing the vehicle.    But I really don't feel like breaking down another front brake system just to take a good photo!