Rotary system
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The rotary machine switching system, or most commonly known as the rotary system, was a type of
automatic telephone exchange telephone exchange, telephone switch, or central office is a telecommunications system used in the public switched telephone network (PSTN) or in large enterprises. It interconnects telephone subscriber lines or virtual circuits of digital syst ...
manufactured and used primarily in Europe from the 1910s. The system was developed and tested by AT&T's American engineering division,
Western Electric The Western Electric Company was an American electrical engineering and manufacturing company officially founded in 1869. A wholly owned subsidiary of American Telephone & Telegraph for most of its lifespan, it served as the primary equipment ma ...
, in the United States, at the same time when Western Electric was also developing the
Panel switch The Panel Machine Switching System is a type of automatic telephone exchange for urban service that was used in the Bell System in the United States for seven decades. The first semi-mechanical types of this design were installed in 1915 in Newark, ...
. When AT&T selected the Panel System for large American exchanges, development and sales of the ''No. 7-A Machine Switching System'', its formal commercial name, were transferred to Western Electric's international division in Belgium. In Europe and other continents the system was met with considerable commercial success. 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 of revertive pulsing and preselection. 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 Panel system was chosen for American large cities, the Rotary system was selected for use in Europe and manufactured at the Bell Telephone Manufacturing factory of
Western Electric The Western Electric Company was an American electrical engineering and manufacturing company officially founded in 1869. A wholly owned subsidiary of American Telephone & Telegraph for most of its lifespan, it served as the primary equipment ma ...
(the
International Bell Telephone Company The International Bell Telephone Company (IBTC) of Brussels, Belgium, was created in 1879 by the Bell Telephone Company of Boston, Massachusetts, a precursor entity to the American Telephone and Telegraph Company (AT&T), initially to sell imported ...
) in
Antwerp Antwerp (; nl, Antwerpen ; french: Anvers ; es, Amberes) is the largest city in Belgium by area at and the capital of Antwerp Province in the Flemish Region. With a population of 520,504,
,
Belgium Belgium, ; french: Belgique ; german: Belgien officially the Kingdom of Belgium, is a country in Northwestern Europe. The country is bordered by the Netherlands to the north, Germany to the east, Luxembourg to the southeast, France to th ...
. The first exchanges were installed in England at
Darlington Darlington is a market town in the Borough of Darlington, County Durham, England. The River Skerne flows through the town; it is a tributary of the River Tees. The Tees itself flows south of the town. In the 19th century, Darlington underwen ...
(10 October 1914) and Dudley (9 September 1916). However the British
General Post Office The General Post Office (GPO) was the state postal system and telecommunications carrier of the United Kingdom until 1969. Before the Acts of Union 1707, it was the postal system of the Kingdom of England, established by Charles II in 1660. ...
standardised on the Step-by-Step (
SXS SxS (S-by-S) is a flash memory standard compliant to the Sony and SanDisk-created ExpressCard standard. According to Sandisk and Sony, the cards have transfer rates of 800 Mbit/s and burst transfer rate of up to 2.5 Gbit/s over the ExpressCard's ...
) system in 1922, and subsequently the SXS Director system for London and other large cities. Six Rotary exchanges were installed in the city of Hull, between 1922 and 1929, where telephones service was supplied by
Hull Corporation (Kingston upon) Hull City Council is the governing body for the unitary authority and city of Kingston upon Hull. It was created in 1972 as the successor to the Corporation of (Kingston upon) Hull, which was also known as Hull Corporation and fou ...
rather than by the GPO. The Rotary system was chosen for
The Hague The Hague ( ; nl, Den Haag or ) is a city and municipality of the Netherlands, situated on the west coast facing the North Sea. The Hague is the country's administrative centre and its seat of government, and while the official capital of ...
, (the Netherlands) and
New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island count ...
in 1913–14, but manufacture was disrupted by the German invasion of Belgium. Dies were moved to England, then to the
Hawthorne Works The Hawthorne Works was a large factory complex of the Western Electric Company in Cicero, Illinois. Named after the original name of the town, Hawthorne, it opened in 1905 and operated until 1983. At its peak of operations, Hawthorne employed 4 ...
of
Western Electric The Western Electric Company was an American electrical engineering and manufacturing company officially founded in 1869. A wholly owned subsidiary of American Telephone & Telegraph for most of its lifespan, it served as the primary equipment ma ...
in America (manufacture resumed at Antwerp in 1920). The first exchanges cutover (placed into service) were
Masterton Masterton ( mi, Whakaoriori), a large town in the Greater Wellington Region of New Zealand, operates as the seat of the Masterton District (a territorial authority or local-government district). It is the largest town in the Wairarapa, a r ...
, New Zealand on 31 May 1919, followed by Courtenay Place and Wellington South in
Wellington Wellington ( mi, Te Whanganui-a-Tara or ) is the capital city of New Zealand. It is located at the south-western tip of the North Island, between Cook Strait and the Remutaka Range. Wellington is the second-largest city in New Zealand by me ...
on 18 October 1919, and Scheveningen, The Hague on 7 January 1920. 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 Administration Postes Télégraphes Téléphones. The first semi-automatic Rotary 7A (McBerty design) was turned on in
Angers Angers (, , ) is a city in western France, about southwest of Paris. It is the prefecture of the Maine-et-Loire department and was the capital of the province of Anjou until the French Revolution. The inhabitants of both the city and the prov ...
in November 1915, and the second in
Marseille Marseille ( , , ; also spelled in English as Marseilles; oc, Marselha ) is the prefecture of the French department of Bouches-du-Rhône and capital of the Provence-Alpes-Côte d'Azur region. Situated in the camargue region of southern Franc ...
on 19 April 1919 (Marseille-Colbert I). Only two Rotary 7A semi-automatic were installed in France. All the other Rotary exchanges in France were 7A1 fully automatic (Gerald Deakin mechanics). The 1 January 1928, The semi-automatic Rotary 7A of Marseille-Colbert 1 was fully automated, maximum capacity lines 10,000. Angers stayed semi-automatic only, capacity approx 3,000 lines. Rotary fully automatic 7A1 was deployed in Nantes on 29 October 1927, Marseille-town ''(first Marseille-Dragon on 5 May 1928)'' and Paris ''(first Carnot on 22 September 1928)'' and Region of Paris in large and exclusive proportion. All the French Rotary 7A and 7A1 were exclusively manufactured in France, with French workers, essentially by ITT-LMT company, and, in subsidiary by French
Ericsson (lit. "Telephone Stock Company of LM Ericsson"), commonly known as Ericsson, is a Swedish multinational networking and telecommunications company headquartered in Stockholm. The company sells infrastructure, software, and services in informat ...
Society and Society Grammont. In 1925
IT&T ITT Inc., formerly ITT Corporation, is an American worldwide manufacturing company based in Stamford, Connecticut. The company produces specialty components for the aerospace, transportation, energy and industrial markets. ITT's three businesses ...
purchased International Western Electric, formerly
Bell Telephone Manufacturing Company The International Bell Telephone Company (IBTC) of Brussels, Belgium, was created in 1879 by the Bell Telephone Company of Boston, Massachusetts, a precursor entity to the American Telephone and Telegraph Company (AT&T), initially to sell importe ...
, in Belgium, from AT&T; as the Bell System complied with regulators to sell its overseas manufacturing interests to settle anti-trust action. In the 1930s, ITT grew through purchasing German electronic companies Standard Elektrizitaetsgesellschaft and
Mix & Genest Mix & Genest was founded on 1 October 1879 by the businessman Wilhelm Mix and the engineer Werner Genest in Berlin-Schöneberg. The company was initially an 1879 branch of the ITT Corporation. It was very successful and became one of the pioneers ...
, both of which were internationally active companies. Apart from the Netherlands (38,100 lines) and New Zealand (48,400 lines), other countries that had installed or ordered Rotary equipment by 1925 were Australia, Belgium (29,000 lines), Denmark, England, France, Hungary, Italy, Norway (41,160 lines), Romania, South Africa, Sweden and Switzerland. There was a total of 104,615 lines in service, and 137,330 lines “proceeding”. Subsequently, at Zurich, Switzerland; the mechanical registers were replaced by
PDP-11 The PDP-11 is a series of 16-bit minicomputers sold by Digital Equipment Corporation (DEC) from 1970 into the 1990s, one of a set of products in the Programmed Data Processor (PDP) series. In total, around 600,000 PDP-11s of all models were sold, ...
computers. In
Kingston-upon-Hull Kingston upon Hull, usually abbreviated to Hull, is a port city and unitary authority in the East Riding of Yorkshire, England. It lies upon the River Hull at its confluence with the Humber Estuary, inland from the North Sea and south-east o ...
which had the only municipal telephone system in the United Kingdom (see
KCOM Group KCOM Group (formerly known as Kingston Communications and latterly KC) is a UK communications and IT services provider. Its headquarters are in the city of Kingston upon Hull, and it serves local residents and businesses with Internet and telep ...
), operated by the Hull City Council, rotary exchanges were operated from 1922 to 1975. In the rest of the United Kingdom, the telephone system was operated by the British Post Office (later
British Telecom BT Group plc (trade name, trading as BT and formerly British Telecom) is a British Multinational corporation, multinational telecommunications holding company headquartered in London, England. It has operations in around 180 countries and is th ...
), which had installed a Rotary exchange at
Darlington Darlington is a market town in the Borough of Darlington, County Durham, England. The River Skerne flows through the town; it is a tributary of the River Tees. The Tees itself flows south of the town. In the 19th century, Darlington underwen ...
(10 October 1914) and
Dudley Dudley is a large market town and administrative centre in the county of West Midlands, England, southeast of Wolverhampton and northwest of Birmingham. Historically an exclave of Worcestershire, the town is the administrative centre of the ...
(9 September 1916), but subsequently decided to use the Strowger system in small and medium cities and the Director system in London (from 1927) and five other large British cities. A Rotary system was installed in
Auckland Auckland (pronounced ) ( mi, Tāmaki Makaurau) is a large metropolitan city in the North Island of New Zealand. The List of New Zealand urban areas by population, most populous urban area in the country and the List of cities in Oceania by po ...
, New Zealand in the central city telephone exchange (WLT) in Wellesley Street in 1924. Other Auckland exchanges with Rotary systems included Devonport 1 and 2 (DA1 and DA2) and Mount Eden 1 (MOD1). These four exchanges were still operating until at least 1970.


Working exhibit

In
Christchurch Christchurch ( ; mi, Ōtautahi) is the largest city in the South Island of New Zealand and the seat of the Canterbury Region. Christchurch lies on the South Island's east coast, just north of Banks Peninsula on Pegasus Bay. The Avon River / ...
, New Zealand at the
Ferrymead Heritage Park Ferrymead Heritage Park is a museum in Christchurch, New Zealand, housing groups with historical themes, mainly transport related. Formerly known as Ferrymead Historic Park, it was founded in 1964 by groups, local government bodies and other i ...
, 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 Auckland (pronounced ) ( mi, Tāmaki Makaurau) is a large metropolitan city in the North Island of New Zealand. The List of New Zealand urban areas by population, most populous urban area in the country and the List of cities in Oceania by po ...
, New Zealand, a rotary exchange was set up as an exhibit at the
Museum of Transport and Technology The Museum of Transport and Technology (MOTAT) is a science and technology museum located in Western Springs, Auckland, New Zealand. It is located close to the Western Springs Stadium, Auckland Zoo and the Western Springs Park. The museum has l ...
at Western Springs. In
Budapest, Hungary Budapest (, ; ) is the capital and most populous city of Hungary. It is the ninth-largest city in the European Union by population within city limits and the second-largest city on the Danube river; the city has an estimated population of ...
, at the Museum of Telephones ( Telefónia Múzeum) there is a still workable 7A1 Rotary Switching system. (The exhibition has been closed until the first part of 2019 due to some reconstruction works.) At the
Norwegian Telecom Museum The Norwegian Telecom Museum (''Telemuseet'', formerly ''Norsk Telemuseum'') was a Norwegian museum with a collection and several exhibits, including a permanent exhibit at the Norwegian Museum of Science and Technology. The administration of the ...
in
Oslo, Norway Oslo ( , , or ; sma, Oslove) is the capital and most populous city of Norway. It constitutes both a county and a municipality. The municipality of Oslo had a population of in 2022, while the city's greater urban area had a population of i ...
there is a 7A2 exchange. 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 Szentes, Hungary, at the Hungarian State Railways telecommunications main body Szeged ( Magyar Államvasutak Zrt. Távközlési Főnökség Szeged) there is a still workable 7D PBX Rotary Switching system. Fully functional in operation. It is kept as a museum style exhibit. It can serve up to 200 subscribers in number group 75 and 76 (7500 to 7699).


US deployment


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

*
International Bell Telephone Company The International Bell Telephone Company (IBTC) of Brussels, Belgium, was created in 1879 by the Bell Telephone Company of Boston, Massachusetts, a precursor entity to the American Telephone and Telegraph Company (AT&T), initially to sell imported ...


External links


UK Telephone History
by Bob Estreich
Museum of Telephones
in Budapest * * Telephone exchanges History of the telephone