Rotary system
The rotary machine switching system, or most commonly known as the rotary system, was a type of
The Rotary and Panel systems were very different systems, but both used the same newly developed component technology, such as Western Electric's latest relays, and the principles of the Lorimer system[1] of revertive pulsing and preselection.[2] The Rotary switches were smaller than the Panel system, and served only 200 rather than 500 stations. The initial version was the model 7A. It was succeeded by 7A1 and 7A2 and a rural system had the designation 7D.
Technology
The Rotary system used 1st and 2nd linefinders; when a customer picked up the phone all free linefinders in the group drove until one picked that customer line. Calls were switched over two, three or four group selection stages followed by a final selector. An office could start with two group selection stages for local calls (a first group level would serve 2000 lines), and be expanded to three group selection stages if it outgrew say 2000 or 4000 lines, depending on the number of first group levels required for other offices in a multi-exchange area.
Deployment
While the
The Rotary system was chosen for The Hague, (the Netherlands) and New Zealand in 1913–14, but manufacture was disrupted by the German invasion of Belgium. Dies were moved to England, then to the Hawthorne Works of Western Electric in America (manufacture resumed at Antwerp in 1920). The first exchanges cutover (placed into service) were Masterton, New Zealand on 31 May 1919, followed by Courtenay Place and Wellington South in Wellington on 18 October 1919,[3] and Scheveningen, The Hague on 7 January 1920.[4] The Hague was the first multi-office area served entirely by the No. 7-A machine system with the cutover of the new Centrum office on 15 February 1924. There were four offices equipped with 23,000 lines; Bezuidenhout, Centrum (or Hofstraat), Hague West (or Marnix), and Scheveningen. The system was owned by The Hague Municipality; initially only 5,000 lines were fully automatic, the rest were semi-automatic.
The Rotary semi-automatic system 7A was chosen for public experiment in October 1912 by the French
In 1925
Apart from the Netherlands (38,100 lines) and New Zealand (48,400 lines), other countries that had installed or ordered Rotary equipment by 1925
In
A Rotary system was installed in Auckland, New Zealand in the central city telephone exchange (WLT) in Wellesley Street in 1924.[8][9] Other Auckland exchanges with Rotary systems included Devonport 1 and 2 (DA1 and DA2) and Mount Eden 1 (MOD1).[citation needed] These four exchanges were still operating until at least 1970.[citation needed]
Working exhibit
In Christchurch, New Zealand at the Ferrymead Heritage Park, the Ferrymead Post & Telegraph Historical Society has a working exhibit of the 7A Rotary Switching system. The display includes a bay of 7A1 Line Finders and a bay of 7A1 Registers.
In Auckland, New Zealand, a rotary exchange was set up as an exhibit at the Museum of Transport and Technology at Western Springs.[8]
In
At the
In Vámosgyörk, Hungary, at the Hungarian State Railways telecommunications main body Miskolc (Magyar Államvasutak Zrt. Távközlési Főnökség Miskolc) there is a still workable 7D PBX Rotary Switching system. Fully functional but not in operation, which has been replaced by an MD 110 system. It is kept as a museum style exhibit. It can serve up to 100 subscribers in number group 41 (4100 to 4199).
In
US deployment
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Notes
- Note: Electrical Communication was published quarterly by the International Standard Electric Corporation. Subsidiaries of the company included the Bell Telephone Manufacturing Company, Antwerp and Standard Electric or Standard Telephones and Cables in various countries. Deakin and Turkhud were with the Bell Telephone Manufacturing Company, Antwerp; Shrimpton was with Standard Telephones and Cables (Australasia).
References
- ^ "Lorimer Brothers". www.telephonecollecting.org. Retrieved 2022-10-28.
- ISBN 9781586033491.
- ^ Shrimpton, E.A. The 7-A Rotary Machine Switching System in New Zealand (Electrical Communication Volume VI Number 2, October 1927)
- ^ Turkhud, B.A. The Hague Telephone Network (Electrical Communication Volume 4 Number 4)
- ^ Deakin, Gerald No. 7-A Machine Switching System (Electrical Communication Volume III Number 3, January 1925)
- .
- ^ "History of Hull Telephone Department". Archived from the original on 2012-01-16. Retrieved 2013-05-19.
- ^ a b "Rare exchange to answer call of duty again". The New Zealand Herald. 17 August 2003. Retrieved 22 June 2018.
- The Auckland Star– archived at Paperspast – paperspast.natlib.govt.nz/. 31 May 1941. Retrieved 12 July 2019.
External links
- UK Telephone History
- Lorimer System by Bob Estreich
- Museum of Telephones in Budapest
- "Photos of rotary telephone equipment". New Zealand Free Lance in Papers Past. 22 October 1919.
- "How to use the automatic telephone; 1919 instructions". Evening Post (NZ) in Papers Past. 17 October 1919.