25 x 4 UNISELECTOR No 15A, 1950's

Uniselector for use in Private Automatic Exchanges (PAX).
Origin Unknown.

Your comments:

• London POLlards exchange (Director type) had these as subscribers uni-selectors, as did LIVingstone (one of the very early London autos after HOLborn) and I think TULse Hill also had some. The things in common between these were that the equipment was VERY old by the mid 1960s when I was in those buildings from time to time, and secondly I guess that Siemens had supplied the original exchange equipment.
  
  I rather think that in LIVingstone the original Directors (Register-Translators) used a very similar uni as the send switch. I recall watching a technician "un busy" a Director in the busy hour, and the send switch was in such a poor state that the self-drive portion of its rotation was slower than the 10 pps stepping! However, it was needed to carry the busy hour traffic, and it connected calls reliably - eventually!
  .......... Paul Ebling, London UK, 13th of May 2013
  
  
• This uniselector was made by Siemens Brothers and used in Siemens 16 public exchanges. When used as a first stage switch, Siemens practice was to refer to it as a Rotary Line Switch.
  .......... Andy Jackson, Sanderstead, Surrey, 26th of February 2011
  
  
• Similar uni selectors were also used as the first stage of switching in Strowger Public Automatic Telephone exchanges and connected the customer to Dial Tone which indicated to the customer that the exchange was ready to receive the dialled numbers
  .......... Mike Fawdrey, Cannock, 24th of February 2011
  
  

A0562