Repairing a hoop wheel from a 30 hr Longcase clock

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 arbour
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 matter of
polishing all the pinions, rebushing were necessary- reassembling
the movement and testing–shouldn’t take more than ten minutes!!!!