Trolleybus

Electric bus taking power from overhead wires

A trolleybus (also known as trolley bus, trolley coach, trackless trolley, trackless tram (in the 1910s and 1920s), road tram or simply trolley) is an electric bus that draws power from dual overhead lines (generally suspended from roadside posts) using spring-loaded or pneumatically raised trolley poles. Two wires, and two trolley poles, are required to complete the electrical circuit. This differs from a tram or streetcar, which normally uses the track as the return path, needing only one wire and one pole (or pantograph).

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