[Bell Historians] Clappers

[Roderic Bickerton]

On 31 July 2010 07:49, David Bagley <david at Z55zKZw_hh4DnXcG3EwCsHmiDgUYTXFzhi2M7C1icm8Illn5Zi0HQOsFWaHcn2V8ZZt32tp3TeqKrawiy64FJZiy.yahoo.invalid> wrote:

> "The clapper pivot needs to be at a node (null) otherwise it will put the
> staple under too much force and break it, which when it was a small piece
> of
> wrought iron cast into the bell was important."


I challenge this, cast in staples had clappers hung of an assembly with wood
and leather, a baldric assembly, which was very forgiving.
In early installations, with bells were hung out, and the flight had more to
do with getting the bell to ring well.
I remember one case where the flight had broken of and the bell lost a lot
of power, would not go up right but was better rung "up wrong", than turned.

On the subject of clapper knock, flight dynamics cant stop the
basic transient shock, only the amount of whiplash loading, so tuning the
flight may reduce clapper knock but cannot eliminate it. I also suspect
a proportion of clapper knock is directly through the bell.
To stop this sound transmission needs a mismatch in density's of the
transmitting medium, so
a timber stock.
an interface, under the bearings,
a different density material between frame foundation beams,
foundation beams on interface pads, rather than directly into walls can all
reduce the path transmission.
the less consistent the tower construction, the lower the transmission, so a
stone tower with the blocks set on a soft mortar and rubble in-filled wont
conduct sound like engineering brick on hard mortar or reinforced concrete.



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