What is a Trolleybus?
Major differences between trolleybuses and trams are that trams have flanged wheels and they operate along rails as a train does, whilst trolleybuses have tyres made of rubber for normal roads. They are literally electic buses!
Trolleybuses get their power from 2 parallel wires overhead, through a set of booms attached to the top of the bus. Trams generally get their energy from a solitary thick overhead wire.
Trams tend only to use single electric contact wires so that they can use the the running rails to complete a circuit. As trolleybuses have no rails and are in effect insulated due to their rubber tyres, need 2 wires to provide a complete electrical circuit.
Some new trolleybus routes were constructed right through until the 1960s - but not long after that the majority of trolleybuses needed replacing. The very small market for trolleybuses in the UK created a vast price difference between them and diesel buses, meaning many operators chose to close their trolley vehicle routes.
The advantages of trolleybuses over trams is that they are able to steer, and so negotiate around obstructions and parked cars. They also able to swerve if necessary. Their electricical booms can swivel to allow the trolleybus to deviate course. Trolleybuses can also be fitted with a battery for auxiliary power.