Trolley-Bus

A trolleybus (also known as trolley bus, trolley coach, trackless trolley, trackless tram – in the 1910s and 1920s[1] – or trolley[2][3]) is an electric bus that draws power from dual overhead wires (generally suspended from roadside posts) using spring-loaded trolley poles. Two wires, and two trolley poles, are required to complete the electrical circuit.