DVD Trolleybuses - UK

Trolleybuses - UK

A trolleybus, also known as trolley bus, trolley coach, trackless trolley, trackless tram or just trolley, is an electrically powered bus that draws its electricity from a network of charged overhead wires, which generally are suspended from posts at the roadside using spring loaded trolley poles fitted to the roof of the vehicle. Two poles are needed, so that one can draw down the live current to power the motor and the other can complete the circuit by carrying the neutral current back to the network. The rubber tyres on a bus do not conduct electricity, therfore the neutral current cannot pass directly to the ground via the wheels, unlike the electric tram can use its steel wheels to take the current to earth through the tramway rails. There are trolleybuses in many cities around the world, although no trolleybus systems now remain in operation in the U.K. however more than 50 systems existed in the past, and a large number of trolleybuses have been preserved, mainly found in working museums.