Hi all, a friend of mine has a train set he sets up every Christmas that runs along a shelf on two walls. So basically the layout is an "L" shape. When the car gets to the end of the track it hits a bumper and reverses direction. I'm wondering how I go about setting up a similar arrangement. What exactly reverses the current so that the train goes the other way? Is it a function in the bumper or is it in the engine itself? I appreciate any help you can give me, thanks.