LORIMER SYSTEM


In the UK there was only one Lorimer Telephone Exchange ever installed in the UK.  This was a 500 line exchange installed in Hereford in 1914.

The use a phone, you first select the number by use of the levers, turn the handle one revolution and then lift the receiver.  The handle wound a spring, which rotated disks, that were positioned by the levers and these in turn dialled the number.  The levers could remain where they were after dialling and it could be said that this phone had the first last number redial facility.

The exchange equipment was driven by a constantly moving shaft.

History

This section is taken from http://www.bobsoldphones.net/Pages/Lorimer/Lorimer%20Brothers.htm.  Please follow the link for more information.

In the 1890s Almon Strowger's automatic telephone switching system was becoming widely known, and it was becoming obvious that automatic switching was going to be needed to carry the volume of calls on large exchanges.  Other inventors set to work, with varying degrees of success.  One such was Romaine Callender, who patented various automatic switches between 1892 and 1896.  His system was ultimately a failure, but it inspired two of his young staff, George and James Lorimer, to continue the experiments and development work.

They started their own firm, Canadian Machine Telephone, in 1897 in Peterborough, Ontario.  Their first exchange was a very basic development of the Callender system.  It was installed in Troy, Ohio in 1897.  Its weaknesses were obvious and they redeveloped it to the point that it was now only vaguely descended from Callender's original concept.  By 1900 they received a patent for it.  They felt that they were ready to sell their new exchange, and converted their small workshop in the nearby town of Piqua into a production workshop under the name of American Machine Telephone.

James Hoyt Lorimer died in 1901 of recurring typhoid and his place was taken by younger brother Egbert.  Although James Hoyt was the true inventor of the team and little further development occurred without his mechanical abilities, the remaining two brothers turned into effective salesmen.  They missed out on a major sale to the Toronto city council when that body changed its mind about getting involved in telephones, but made minor sales to other smaller towns in Canada and the United States.  The biggest was a 500 line exchange in Atlanta.

Although these apparently operated satisfactorily, the Lorimers wanted a big sale to show off their system.  When the Edmonton Telephone Department approached them in 1906 it appeared that their big moment had arrived.  Unfortunately this was where it all fell apart.  There were unforeseen problems with a larger exchange, and without James Hoyt Lorimer's inventive abilities these problems proved hard to resolve.  The cut over date dragged on for two years without a satisfactory exchange being delivered.  Edmonton cancelled the contract and gave it instead to the Automatic Electric company using Strowger's system.  Automatic Electric installed a working system within two months.

Some interest was shown in the Lorimer system in Europe, and a new company, Societe Internationale de l'Autocommutateur Lorimer, was formed in Paris in 1908 to market the system.  Although they made some sales to France (Paris and Lyon), Britain (Hereford) and Italy (Rome), mostly for the purpose of evaluation by the local administrations, the poor reliability of the exchanges and the slow delivery told against them.  The initial sales were not followed up by more orders.  The British example appears to be typical.  The British Post Office contracted for an evaluation exchange at Caterham in about 1912, but because of the delays it was eventually installed as a 500-line exchange at Hereford in 1914.  With the outbreak of the first World War, supplies and support from Canada would be erratic, so the Post Office standardised on the Automatic Electric Strowger system.  It was now being produced in Britain by an offshoot of the British Insulated and Helsby company, and was a becoming a proven and refined system - unlike the Lorimer system.  The Hereford exchange eventually settled down and gave reliable service, but the BPO had already made up its mind.

The Lorimer firm went bankrupt in 1923, but before this the value of its switching system was recognised by no less than American Telephone and Telegraph, the Bell company. AT&T had been watching the growth of Automatic Electric with increasing concern, but because of their need to finance growth, they had not developed an automatic system of their own.  An engineering team led by F. R. McBerty was developing one, but they lagged seriously behind Automatic Electric.  They had no systems in operation to refine or test their designs on. Western Electric bought the patent rights from the struggling Lorimer company in 1903 and set about redeveloping it into a reliable system.  With their resources and prior research they were able to refine the system far better than Lorimers could.  Their engineers produced two versions, the Panel and Rotary systems.  The Panel system went into production in the U.S. and stayed in operation until the 1950s.  The Rotary system, named for the rotating disks used in the switchgear, was produced in Europe by Bell Telephone Manufacturing in Antwerp and later at Woolwich in Britain.  It proved popular in Europe, although sales in Britain were never as high as was hoped.  It continued in production in Antwerp when Bell / AT&T's overseas assets were bought out by ITT in 1925.  Both systems used a (by now) conventional rotating dial rather than Lorimers' switch selectors, and so the ancestry of the system was not evident.

The Lorimer System

Let us now have a look at Lorimer's technology. The telephones were distinctive, but their low production numbers make them quite rare and few still exist.  To provide the switching pulses, Lorimers used a disk-and-lever selection system. Four disks of contacts were built into the front of the telephone.  The number was selected by pulling each lever to the correct digit of the phone number, corresponding to thousands, hundreds, tens, etc.  The number selected was displayed in a small window.  Lorimers called these disks "dials", and this is where the term "dialling" appears to have come from.  A handle was cranked to wind a clockwork mechanism, and the clockwork rotated the disks at a constant speed and sent dialling pulses to the exchange.  Although the system seems clumsy, Lorimers made a virtue of it by claiming that it allowed the user to check the number before dialling, reducing the risk of wrong numbers.  The signal was sent to a preselector, an original Callsender concept.

The exchange switchgear was just about the reverse of the phones.  Disks carrying one hundred contacts constantly rotated and a series of wipers completed the circuit when the disk declutched and stopped under the influence of the dialling pulses.  It was a somewhat slower switching system than the Strowger, but took up less room and used a revolving switch rather than Strowger's bimotional switch, so it would have been quieter and smaller.  Unfortunately there were problems with the dialling speed generated by the clockwork in the telephones not matching the switching rotation speed at the telephone exchange, and the exchange gear itself needed constant attention to the bearings, clutches and motors to keep the rotation speed constant.  From the illustration it can be seen that most of the switchgear and drive shafts (along the bottom of the frame) were exposed to dust.  There is a working example of the heavily revised Western Electric Rotary exchange at the Ferrymead Museum in New Zealand.  The photos can be seen on their website at http://ptsociety.no-ip.org/ex_rotary.php

The cost of the Lorimer switchgear was lower, which made it appealing to new customers.  The Edmonton system was quoted at $34 per line compared to Automatic Electric's $40 per line.  The exchanges came in 100-line modules that could easily be extended, and took up less floor space than the Automatic Electric system.  Power consumption would probably have been lower as well.  Unfortunately these advantages could not offset the fact that the Lorimer system was unrefined and unreliable.  Lorimers did not have the financial backing or technical support to refine out the problems.

The work of the Lorimer brothers has lapsed into obscurity, just a name sometimes mentioned in relation to early automatic switching. It deserves wider recognition.

References

Knappen R "Old Telephones Price Guide and History of Old Telephones" 1980.

Rens, Jean-Guy "For One Brief, Shining Moment - The Lorimer Brothers" Published in "Telecom History" 1995-1

Canada Science and Technology Museum website, http://www.sciencetech.technomuses.ca/English/collection/conn4.cfm

Hallas, Sam, British Telecom Museum memorial website, http://www.samhallas.co.uk/museum/telephone-2.htm

Kline J. A. "The Development of the Austomatic Selector" Published in The Telecommunications Journal of Australia, June 1947.

 

Telephones

Lorimer Table Set Lorimer calling mechanism
Two curved number strips have been removed
   
Lorimer Wall Set Lorimer wall set showing number selector mechanism

 

Lorimer Wall Set showing the mechanism exposed

Lorimer exchange showing the constantly turning drive shaft

100 line switching unit with seven connective divisions or cord circuits

 

 
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Last revised October 02, 2011

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