Trolley pole

The use of overhead wire in a system of current collection is reputed to be the 1880 invention of Frank J. Sprague,[1] but the first working trolley pole was developed and demonstrated by Charles Van Depoele, in autumn 1885.

[3] Credit for development of the first working trolley pole is given to Charles Joseph Van Depoele, a Belgian engineer who moved to the United States in 1869.

Van Depoele made the first public demonstration of the spring-loaded device on a temporary streetcar line installed at the Toronto Industrial Exhibition (now the CNE) in autumn 1885.

Known as the Richmond Union Passenger Railway, this 12-mile (19 km) system was the first large-scale trolley line in the world, opening to great fanfare on February 12, 1888.

The sliding trolley shoe provided better electrical contact (with a reduction in arcing), and it dramatically reduced overhead wire wear.

The pole sits atop a sprung base on the roof of the vehicle, with springs providing the pressure to keep the trolley wheel or shoe in contact with the wire.

However, pushing of the pole (called "back-poling" in the US or "spear-poling" in Australia), was quite common where the trams were moving at slow speeds, such as at wye terminals (also known as reversers) and whilst backing into the sheds.

To reduce electrolytic corrosion of underground pipes and metallic structures, most tram lines are operated with the wire positive with respect to the rails.

While more complex than the trolley pole, the pantograph has the advantage of being almost free from dewiring, being more stable at high speed, and being easier to raise and lower automatically.

Trams or light rail cars equipped with pantographs normally cannot operate on lines with overhead wiring designed for trolley-pole collection.

For this reason, these systems and a few others worldwide retain use of trolley poles, even on new streetcars, in order to avoid the difficulty and expense of modifying long stretches of existing overhead wires to accept pantographs.

In 1947, composer Samuel Barber wrote the now-classic orchestral and vocal piece Knoxville: Summer of 1915, based on the childhood reminiscences of James Agee.