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The stud contact system is an obsolete ground-level power supply system for electric trams. The studs were cylinders with their tops flush with the road surface, and connected to an electrical cable underground. The studs contained a switch mechanism that made an electrical connection with the top of the stud when a car with a strong magnet at its underside passed over it, before automatically disconnencting. Electrical current was collected from the studs by a "skate" or "ski collector" under the tramcar.
Stud contact systems were implemented from 1899 to 1921, [1] and were short-lived due to safety issues. [2] For example, one system by Diatto had switches that contained mercury, which often leaked or adhered to the side of the stud cylinder and kept the exposed top electrified. A system by Dolter implemented switches with pivot arms, which tended to get stuck in the electrified position. Similar systems were operated by Thomson-Houston in Monaco from 1898 to 1903, by František Křižík in Prague on the King Charles Bridge from 1903 to 1908, [1] : 109–116 and others such as Griffiths-Bedell, Lorain, and Robrow. Like conduit current collection systems and the modern ground-level power supply systems, stud contact systems were chosen for aesthetic reasons when overhead wire systems would be obtrusive.
Most electric railway systems take the power from an external generator. This means the electricity has to be collected while the locomotive is moving. In this context a locomotive refers to any electric vehicle on a railway track or tramway track.
Generally electric locomotives collect power through a third rail or an overhead wire. The full circuit is completed by track rails. For main line railways with their protected lines overhead lines and third rails are not a problem. Tramways operate in cities. This means that the third rail system is not really practical. It has been used, protection being offered to other road users by placing it in a central groove. Even so, the ingress of dirt and water can cause problems.
An alternative solution is to use studs. All the systems have a switch in the stud and a means to switch on the stud only while it is covered by the moving vehicle. As at least one stud must be covered by the collector at all times a long collector is used. The length has to be slightly greater than the maximum distance between any two studs. This collector is known as a skate or ski collector. This type of electrical power collector needs to move in the vertical plane to allow for natural differences in the height of the power supply studs. It is used on some full size tramway systems where there is a need for overhead wires not to be used, usually in areas of scenic value.
The stud contact system is also used on model railway systems (e.g. Märklin) as the center line of studs is less obtrusive than a single central rail. For outdoor model railway systems the use of a stud supply system with a skate/ski collector has certain practical advantages. The system is inherently self-cleaning. While the track may not be perfect, with both rails acting as the return part of the system in parallel electrical pick-up problems are substantially reduced. [3] [ page needed ]
While the system was generally confined to the larger gauges (O gauge and above) the Märklin company has for many years used a version of the system (known as the Märklin system) for their HO gauge range. Peco Products make studding for their 00/H0 track range. Part nos SL-17 for track and SL-18 for turnouts. [3] [ page needed ]
Modern use of the system is largely restricted to garden railways where it has the advantage of being compatible with unmodified live steam locomotives. While it is possible to insulate model live steam locomotives so that they can operate on two rail electrified track, it is difficult and trouble prone especially where the model is likely to come into contact with water. [3] [ page needed ]
While the obvious use is on railway power collection, the system also has applications wherever electrical energy needs to be transferred from a static source to moving user, or vice versa.
The Brown Surface Contact System was manufactured by Lorain.
The Diatto stud system was the most common in France, with over 20,000 studs in use. It was invented by an Italian, Alfredo Diatto of Turin and was first installed in Tours in 1899, followed by four of the Paris tramway companies in 1900.
For the Dolter system a conductor cable was laid in a trench between the rails. At 9-foot (2.7 m) intervals a box was fitted between the rails that contained a stud (which protruded about 1 inch (25 mm) above the road) and a bell crank. A magnet on a passing tram attracted this crank which then moved to make contact between the conductor cable and stud; once the tram moved away the crank dropped away and the stud was no longer connected to the cable. A long skate was suspended beneath each tramcar which was magnetised by electro-magnets and so both operated the cranks and collected the current that both moved the tram car and powered the electro-magnets. A small battery was carried to charge the electro-magnets should the power be interrupted. The negative return current passed through the rails. [4]
The town council of Torquay did not want their seaside resort disfigured by the poles and overhead wires of a conventional electric tramway and so invited the Dolter Electric Traction Company to construct a tramway using their stud-contact system. A horse was killed after it stepped on a live stud during construction of the Torquay Tramways. [4] Each tram car was then fitted with a bell connected to a special contact arm to warn the driver if a stud remained live after it had passed. The conductor of the tram then had to reset the crank using an insulated mallet. [5] During the Board of Trade inspection of the tramway four such studs were detected during about 8 miles (13 km) of tests. [4] There were also frequent problems with trams being stopped when a stud failed to be made live when needed. [5] The network covered 6.79 miles (10.93 km) and opened in stages during 1907 and 1908. On 27 January 1910 a snow storm stopped all the trams as they couldn't make contact with the studs. It was converted to overhead collection in 1911 shortly before it was extended to Paignton where the town council had refused to allow the Dolter system to be used. [6]
A short Dolter system also opened in 1907 in Hastings along the seafront to connect two sections of a network that otherwise used overhead collection. It lasted until 1913. For the next eight years the trams that worked along Hastings sea front were fitted with a small motor to enable them to move between the two sections of overhead wire, but in 1921 wires were provided along the section. [7]
The Mexborough & Swinton Tramway used the Dolter system from 1907 until 1908 when it was converted to overhead supply.
The Griffiths-Bedell stud system of the Lincoln Corporation Tramways.
A tram is a urban rail transit in which vehicles, whether individual railcars or multiple-unit trains, run on tramway tracks on urban public streets; some include segments on segregated right-of-way. The tramlines or tram networks operated as public transport are called tramways or simply trams/streetcars. Because of their close similarities, trams are commonly included in the wider term light rail, which also includes systems separated from other traffic.
An overhead line or overhead wire is an electrical cable that is used to transmit electrical energy to electric locomotives, electric multiple units, trolleybuses or trams. The generic term used by the International Union of Railways for the technology is overhead line. It is known variously as overhead catenary, overhead contact line (OCL), overhead contact system (OCS), overhead equipment (OHE), overhead line equipment, overhead lines (OHL), overhead wiring (OHW), traction wire, and trolley wire.
A third rail, also known as a live rail, electric rail or conductor rail, is a method of providing electric power to a railway locomotive or 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 fully segregated from the outside environment. Third-rail systems are usually supplied from direct current electricity.
An electric locomotive is a locomotive powered by electricity from overhead lines, a third rail or on-board energy storage such as a battery or a supercapacitor. Locomotives with on-board fuelled prime movers, such as diesel engines or gas turbines, are classed as diesel–electric or gas turbine–electric and not as electric locomotives, because the electric generator/motor combination serves only as a power transmission system.
Railway electrification is the use of electric power for the propulsion of rail transport. Electric railways use either electric locomotives, electric multiple units or both. Electricity is typically generated in large and relatively efficient generating stations, transmitted to the railway network and distributed to the trains. Some electric railways have their own dedicated generating stations and transmission lines, but most purchase power from an electric utility. The railway usually provides its own distribution lines, switches, and transformers.
The use of a third rail in rail transport modelling is a technique that was once applied, in order to facilitate easier wiring.
A trolley pole is a tapered cylindrical pole of wood or metal, used to transfer electricity from a "live" (electrified) overhead wire to the control and the electric traction motors of a tram or trolley bus. It is a type of current collector. The use of overhead wire in a system of current collection is reputed to be the 1880 invention of Frank J. Sprague, but the first working trolley pole was developed and demonstrated by Charles Van Depoele, in autumn 1885.
Ground-level power supply, also known as surface current collection or, in French, alimentation par le sol, is a concept and group of technologies that enable electric vehicles to collect electric power at ground level instead of the more common overhead lines.
A pantograph is an apparatus mounted on the roof of an electric train, tram or electric bus to collect power through contact with an overhead line. The term stems from the resemblance of some styles to the mechanical pantographs used for copying handwriting and drawings.
Conduit current collection is an obsolete system that was used by some electric tramways to pass current to streetcars via a "conduit", a small tunnel under the roadway. Modern systems fall under the term ground-level power supply.
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 was replaced by the pantograph or the trolley pole, itself often later replaced by the pantograph.
Tramway track is used on tramways or light rail operations. As with standard rail tracks, tram tracks have two parallel steel rails, the distance between the heads of the rails being the track gauge. When there is no need for pedestrians or road vehicles to traverse the track, conventional flat-bottom rail is used. However, when such traffic exists, such as in urban streets, grooved rails are used.
The Mexborough & Swinton Tramways Company was a tramway system in the West Riding of Yorkshire, England, founded in 1902 and which began services in 1907 linking Rotherham with the Old Toll Bar, Mexborough. Its routes served Manvers Main Colliery, Wath upon Dearne and the towns of Rotherham, Rawmarsh, Swinton and Mexborough.
Railway electric traction describes the various types of locomotive and multiple units that are used on electrification systems around the world.
A current collector is a device used in trolleybuses, trams, electric locomotives and EMUs to carry electric power (current) from overhead lines, electric third rails, or ground-level power supplies to the electrical equipment of the vehicles. Those for overhead wires are roof-mounted devices, those for rails are mounted on the bogies.
Torquay Tramways operated electric street trams in Torquay, Devon, England, from 1907. They were initially powered by the unusual Dolter stud-contact electrification, but in 1911 was converted to more conventional overhead-line supply. The line was extended into neighbouring Paignton in 1911 but the whole network was closed in 1934.
Wolverhampton Corporation Tramways operated a tramway service in Wolverhampton between 1902 and 1928.
The Bessbrook and Newry Tramway operated a 3 ft narrow gauge, hydro-electrically powered tramway transporting passengers and freight between Bessbrook and Newry in Northern Ireland between 1885 and 1948.
The Seebach-Wettingen railway electrification trial (1905-1909) was an important milestone in the development of electric railways. Maschinenfabrik Oerlikon (MFO) demonstrated the suitability of single-phase alternating current at high voltage for long-distance railway operation with the Seebach-Wettingen single-phase alternating current test facility. For this purpose, MFO electrified the 19.45-kilometre-long Swiss Federal Railways (SBB) route from Seebach to Wettingen at its own expense with single-phase alternating current at 15,000 volts.