Shifting Trolley

A trolley bus or trackless trolley is an electrically powered bus that draws its power from a pair of parallel overhead wires by means of two trolley poles. (Electric rail vehicles require only one overhead wire as they complete the electrical circuit by returning power through rails. The word “trolley” derived from the wheel that was used at the upper end of the trolley pole that ran along the overhead wire and drew the current that powered the car.