TELEPHONE No. 746 & 8746
VOLUME CONTROL AND UNICOIL BELL
Some later variants of the Telephone No. 746 (Mark 3) and No. 8746 were fitted with a single coil bell, called the Unicoil bell (Bell No. 79A).  This bell could also be supplied with a volume control.  The control mechanism was also fitted to the Bell Unit No. 776 which was used on the Telephone No. 776-1.

Drawings
Lever Assembly - 93570.
Latch Assembly - 93571/1 and 93571/2.
Bell No. 79A - 93053.
 

The above picture shows the Unicoil bell and volume mechanism.  The lever projecting from the front of the case, can be moved from side to side.  There is a spring attached to the lever (visible between the bell plate and the white plastic moulding) and this spring restricts the movement of the bell clapper arm.
 
The volume arm removed from the mechanism.  The restrictor spring is shown centrally.

 
 
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Last revised: January 28, 2023

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