BELL No. 57
Trembler bell for preliminary signal and special cases in Post Office buildings.  The Bell is similar in construction to the Bell No. 44.

The Mark 1 is wooden cased whilst the Mark 2 has a plastic casing.

The Mark 2 was introduced circa 1957.

Bell No. 57A - Twin 50 ohm coils (Conductor diameter - 0.0108ins with 3460 turns).
Bell No. 57B - Twin 250 ohm coils (Conductor diameter - 0.0068ins with 6000 turns).

The bell uses a 7inch diameter wire gong (Bell-gong No. 22).

Bell No. 57B is pictured below.

Diagram - N657.

Drawing - 90903 (Mark 2).

Specification - S2.

Early variant - wooden cased Later variant - plastic cased (does not include the wooden plate)

 

 
 
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Last revised: December 04, 2025

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