Trolleybus

A trolleybus (also known as electric bus, trolley bus, trolley coach, trackless trolley, trackless tram or simply trolley) is a bus powered by two overhead electric wires, from which the bus draws electricity using two trolley poles. Two poles are required in order to accommodate the return current, which can not pass to the ground as in the case of an electric tram or streetcar since trolleybuses use rubber tires rather than steel wheels on rail.

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The trolleybus's development dates to the early 1900s, when they seemed to be a natural compromise between the electric streetcar and the petroleum-powered bus. Trolleybus systems could avoid obstacles in the street which a streetcar could not, and did not require as much capital investment as a streetcar line.

Bus: :This article is about the form of transport. See computer bus or electrical bus for the use of the term in computing and electronics respectively, or places like Bus, Pas-de-Calais and Bus-Saint-R?my....

Electricity: :Separate-but related articles are Electrical energy, and Electric power...

Trolley pole: Trolley poles are usually tapered cylindrical poles of wood or metal, used to transfer electricity from a "live" overhead wire to the control and propulsion equipment of a trolley car, tram or trolley bus. This system of current collection was an invention of Frank J. Sprague....