# [Bell Historians] SG/WI & counterweight - was Tuning forks

Bickerton, Roderic K (SELEX) (UK) roderic.bickerton at 48qOucqujguMb0KS91RqPjmA5QW5JysYlsG4SV43ybRdrsw58ZQaHtGGuAL3dOcvJget3Dfr2o6xYHl0QPfK_3R874dWaIW7fA.yahoo.invalid
Wed Apr 19 11:31:27 BST 2006

```A thought on counterweights
Thinking about the energy which swings the clapper with respect to the bell.
A counterweight is above the clapper pin and must end up with its mass centre close to the bell baring line. It is not therefore going to have significant energy imparted into it by the bell rotation.
The total energy imparted into a clapper is not likely to be much influenced by a counter weight but the clapper inertia will be increased, slowing it down.
More mass, less velocity but similar total energy.
Consider what happens when a counter balanced clapper hits.
the ball stops.
the counter weight is at the end of a spring, the clapper shaft and will not stop so quickly.
as has been noted in previous discussion a normal clapper bounces or de-weights immediately following impact allowing the bell to resonate freely before the clapper settles back and damps the bell.
In a counterbalanced clapper the part of the energy in the counter weight will force the clapper against the bell as it slows down against the spring force of the clapper shaft.
If a rebound occurs it will be much later than with a normal clapper and will happen when the counter weight has completed its over swing following impact, and the energy trapped in the clapper shaft acting as a spring rotates the counter weight which tries to lift the clapper.
this lift is to late to prevent the clapper damping the bell.

Could this action look like a much harder hit and produce a rather poor tone because of excess damping, when the initial impact is actually less by the amount of energy in the counter weight movement with respect to the bell?
Rod.

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