Editing Overhead line (section)

== Overview ==
Electric trains that collect their current from overhead lines use a device such as a [[Pantograph (transport)|pantograph]], [[bow collector]] or [[trolley pole]]. It presses against the underside of the lowest overhead wire, the contact wire. Current collectors are electrically conductive and allow current to flow through to the train or tram and back to the feeder station through the steel wheels on one or both running rails. Non-electric [[locomotive]]s (such as [[Diesel locomotive|diesels]]) may pass along these tracks without affecting the overhead line, although there may be difficulties with [[Structure gauge|overhead clearance]]. Alternative electrical power transmission schemes for trains include [[third rail]], [[ground-level power supply]], [[Electric vehicle battery|batteries]] and [[electromagnetic induction]].

Vehicles like buses that have rubber tyres cannot provide a return path for the current through their wheels, and must instead use a pair of overhead wires to provide both the current and its return path.