BIAS SPRINGS | |||||||
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In situations where bell tinkle was produced on customer telephone installations a bias spring was fitted on the bells used on site which stopped the tinkling. In most instances the GPO knew what combination of equipment could cause bell tinkle and certain Bellsets were produced with a bias spring included as standard.
Originally, on the "Bell No. 1A, unmounted",
the bias spring was a spiral spring fixed to the bell ringer frame at one end
and the other end attached to an arm fixed to the armature. The frame
actually just has a hole drilled through it and what looks like a slot headed screw is in
fact a two pronged pin, which is a push fit into the drilled hole.
Fitting a bias spring to an existing bell ringer was obviously not an easy task for field staff and a "Bell No. 1A, unmounted, with Bias Spring" was made available as a replacement part. Around 1933 a new standard bell ringer, the "Bell No. 59A, unmounted", was introduced and obviously a bias spring may be required. Two new bias springs were also introduced, Part 1/SSP/593 was for use on the "Bell No. 1A unmounted" and Part 2/SSP/593 was for the "Bell No. 59A unmounted". These were a much simpler flat metal strip which could be retrofitted easily to existing bell ringers (see pictures below). After 1933 no bells were supplied with bias springs pre-installed and the
spring would have to be ordered separately. Bell No. 1A unmounted with Bias Spring
The Bias Spring is the right of the picture
Close up of the rod
Close up of the rod and spring Part 1/SSP/593
Part 2/SSP/593
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Last revised: May 03, 2026FM |
