I am building a train for my grandkids, and it is based on the style of an old steam train. My dilema has been attempting to design a working coupling rod from the drive wheels to the other set of wheels. So far the trouble I've been having is keeping the wheels in sinc. and the rod to stay horizontal. Does anyone know how to design and set up a coupling rod situation? Or know where I can find out? It's a trackless train and the secondary wheels are just for looks and sit just off the ground so as not to interfere with the front steering wheels. Thanks for your help. Jeff