Reversing loop (balloon loop)

A reversing loop turns a track back onto itself in a 180° loop — the train returns onto the same track heading the opposite way. Operationally handy, electrically tricky: in two-rail DC systems the loop causes a short circuit because left and right rail meet; reverse-loop modules or insulated sections solve it. In three-rail (stud-contact) systems such as Märklin the reversing loop is electrically harmless.