Mark- Now I see what you are getting at. The second link you included clearly shows the largish wheel that is at the rear of the idler arm. It appears to run along inside of a cast-in groove in the brake body as the brakes are applied.
I included some photos of the side and rear of my front brake. It looks like a slightly different design that still uses the same principle.
Quick release in open position
Roller incorporates into cable attachment bolt
Quick release in closed position
Best view of the roller wheel of which you speak.
There is no quick release or roller built into the rear brake mechanism