Stud contact system

The studs were cylinders with their tops flush with the road surface, and connected to an electrical cable underground.

[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.

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] Modern use of the system is largely restricted to garden railways where it has the advantage of being compatible with unmodified live steam locomotives.

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.

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.

[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.

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.