BELL No. 40

Wooden indoor D.C. Trembler bell, with Church style gong, used on fire alarm systems.  Later bells casings were constructed out of plastic.

Bell 40A - Twin 50 ohm coils, 2-10 volts - used  on London Fire Brigade systems.
Bell 40B - Twin 250 ohm coils, 10-50 volts - used in PO buildings and specified for omnibus call-bell systems.

Fitted with Bell-gong No. 21 (4.5in diameter x 3.1in - Church style).

Found in the Rate Book 1947 and 1956.

GPO Engineering Instructions on Fire Systems

Diagram - N640.

Picture of wooden Bell taken 1937.

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Last revised: December 02, 2020