Electric current collectors are used for trolleybus

Trolleybus

A trolleybus is an electric bus that draws its electricity from overhead wires using spring-loaded trolley poles. Two wires and poles are required to complete the electrical circuit...

es, tram

Tram

A tram is a passenger rail vehicle which runs on tracks along public urban streets and also sometimes on separate rights of way. It may also run between cities and/or towns , and/or partially grade separated even in the cities...

s, electric locomotive

Electric locomotive

An electric locomotive is a locomotive powered by electricity from overhead lines, a third rail or an on-board energy storage device...

s or EMUs

Electric multiple unit

An electric multiple unit or EMU is a multiple unit train consisting of self-propelled carriages, using electricity as the motive power. An EMU requires no separate locomotive, as electric traction motors are incorporated within one or a number of the carriages...

to lead electrical power from overhead lines

Overhead lines

Overhead lines or overhead wires are used to transmit electrical energy to trams, trolleybuses or trains at a distance from the energy supply point...

 or electrical third rail

Third rail

A third rail is a method of providing electric power to a railway train, through a semi-continuous rigid conductor placed alongside or between the rails of a railway track. It is used typically in a mass transit or rapid transit system, which has alignments in its own corridors, fully or almost...

s to the electrical equipment of the vehicles.

Typically, they have one or more spring-loaded arms that permits the working engagement with the rail or overhead wire and a collector or contact shoe in running engagement with the wire or rail. The collector arms pushes the contact shoe against the contact wire or rail. As the vehicle moves, the contact shoe slides along the wire or rail to draw the electricity needed to run the vehicles motor.
The current collector arms are electrically conductive but mounted insulated

Electrical insulation

thumb|250px|[[Coaxial Cable]] with dielectric insulator supporting a central coreThis article refers to electrical insulation. For insulation of heat, see Thermal insulation...

 on the vehicles roof, side or base. A samewise insulated cable

Cable

A cable is two or more wires running side by side and bonded, twisted or braided together to form a single assembly. In mechanics cables, otherwise known as wire ropes, are used for lifting, hauling and towing or conveying force through tension. In electrical engineering cables are used to carry...

 connects the collector with the switch

Switch

In electronics, a switch is an electrical component that can break an electrical circuit, interrupting the current or diverting it from one conductor to another....

, transformer

Transformer

A transformer is a device that transfers electrical energy from one circuit to another through inductively coupled conductors—the transformer's coils. A varying current in the first or primary winding creates a varying magnetic flux in the transformer's core and thus a varying magnetic field...

 or motor

Electric motor

An electric motor converts electrical energy into mechanical energy.Most electric motors operate through the interaction of magnetic fields and current-carrying conductors to generate force...

. The steel rails

Rail profile

The rail profile is the cross sectional shape of a railway rail, perpendicular to the length of the rail.In all but very early cast iron rails, a rail is hot rolled steel of a specific cross sectional profile designed for use as the fundamental component of railway track.Unlike some other uses of...

 of the tracks  act as the electrical return

Ground (electricity)

In electrical engineering, ground or earth may be the reference point in an electrical circuit from which other voltages are measured, or a common return path for electric current, or a direct physical connection to the Earth....

.

Electric vehicles that collect their current from overhead line system use different forms of one- or two-arm pantograph collectors

Pantograph (rail)

A pantograph for rail lines is a hinged electric-rod device that collects electric current from overhead lines for electric trains or trams. The pantograph typically connects to a one-wire line, with the track acting as the ground wire...

, bow collector

Bow collector

A bow collector is one of the three main devices used on tramcars to transfer electric current from the wires above to the tram below. While once very common in continental Europe, it has now been largely replaced by the pantograph.-Origins:...

s, or trolley pole

Trolley pole

A trolley pole is a tapered cylindrical pole of wood or metal, used to transfer electricity from a "live" overhead wire to the control and propulsion equipment of a tram or trolley bus. The use of overhead wire in a system of current collection is reputed to be the 1880 invention of Frank J....

s. The current collection device presses against the underside of the lowest wire of an overhead line system, which is called a contact wire.

Contact shoe

Electric railways with third rail

Third rail

A third rail is a method of providing electric power to a railway train, through a semi-continuous rigid conductor placed alongside or between the rails of a railway track. It is used typically in a mass transit or rapid transit system, which has alignments in its own corridors, fully or almost...

s in tunnel

Tunnel

A tunnel is an underground passageway, completely enclosed except for openings for egress, commonly at each end.A tunnel may be for foot or vehicular road traffic, for rail traffic, or for a canal. Some tunnels are aqueducts to supply water for consumption or for hydroelectric stations or are sewers...

s carry collector shoes projecting laterally (sideways) from their bogie

Bogie

A bogie is a wheeled wagon or trolley. In mechanics terms, a bogie is a chassis or framework carrying wheels, attached to a vehicle. It can be fixed in place, as on a cargo truck, mounted on a swivel, as on a railway carriage/car or locomotive, or sprung as in the suspension of a caterpillar...

s. A contact shoe is also used on ground-level power supply

Ground-level power supply

Ground-level power supply, also known as surface current collection and Alimentation par Sol is a modern method of third-rail electrical pick-up for street trams. It was invented for the Bordeaux tramway, which was constructed from 2000 and opened in 2003. Until 2011, this is the only place it is...

 systems and stud contact system

Stud contact system

The Stud Contact System is a once-obsolete ground-level power supply system for electric trams. Power supply studs were set in the road at intervals and connected to a buried electric cable by switches operated by magnets on the tramcars. Current was collected from the studs by a "skate" or "ski...

s. A pair of contact shoes was used on underground current collection systems

Conduit current collection

Conduit current collection is a system of electric current collection used by electric trams, where the power supply is carried in a channel under the roadway, rather than located overhead.-Description:...

.