Repairing a hoop wheel
from a 30 hr Longcase clock
I have in for repair at the moment a 30hr Longcase clock which
has suffered broken teeth on the hoop wheel-- twice!!
Clock as first seen with top plate removed
wheel as taken from the clock, you can see it's broken one tooth and
taken the tip off another!
if correctly repaired this shouldn't happen, so why has it?
The same wheel after cleaning, you can clearly see a
new tooth has been inserted at one time- but the clock has suffered the
same fate! The most common thing that causes this damage is too heaver
weight ( this clock's weight weighed 14 pounds!) or the fly to tight on
it's arbour I think in this case both were to blame. on closer
examination the fly was found to be soldiered to it's arbour!!
The fly on the strike side of any clock is very
important, it not only controls the speed of the hammer on the bell but
also dissipates the energy in the striking train when it
suddenly comes to a halt, that energy has to go somewhere and if the fly
can't slip on it's arbour and absorb this energy it will cause a bounce
and as shown here will eventually break the teeth, it could also cause
the locking lever to lift and the clock to strike the next hour --AND
THE NEXT --AND THE NEXT!!!
The soldier was removed and the spring across the
was set at the correct tension to give no judder or bounce
on the hoop wheel when the clock finished striking
The hoop wheel was repaired-- it is now a little
polishing all the pinions, rebushing were necessary- reassembling
the movement and testing--shouldn't take more than ten minutes!!!!
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