train wheel

Took some books back to the library today, & behind the library there are train tracks with a train that is always "parked" there--it never gets moved for whatever reason--so as it was getting cloudy & is supposed to rain all day, I walked on over to see what I could find to blip before the icky weather comes back! I loved the shapes & industrial look of (what I think are) the breaks and metal wheel of the train. Well, the wheel part is obvious, just not sure about the break part! If my husband were home I'd ask him, as he carries all the "technology" info in the family!! Ha!