Accutron: Seconds band moves. Hour minute don’t move

[standarsh]

I understand this seems to be a common problem related to the canon. Does anyone have any advice or a link to a manual or diagram that can explain how to fix this?

 

the watch gums fine and when setting it the hour and minute hands move correctly. 

[nickelsilver]

Which model is it? When was it last serviced?

 

Accutrons are backwards of mechanical watches, in that you have the power source turning the escape wheel, which then powers the train up through the hands. In a mechanical watch there is an increase in speed and a reduction of torque from each gearing to the next, so there is almost no power on the escape wheel. In an Accutron the tiny power and movement of each vibration of the tuning fork is increased by 7 or 8 fold at each gear set, so that at the hour and minute hands there is tremendous power. The instantaneous date system on a 218 model will shake your wrist! And it would stop or hinder a regular mechanical watch.

 

The upside is a well adjusted Accutron is very reliable and runs for years and years, the downside is that they will run long after the lubrication had dried and grind the pivots to dust. I suspect the friction between the driving wheel and canon pinion has become weak, and the canon pinion and hour wheel are sticky, so the watch runs but doesn't move the hands. As the seconds pinion is before this intersection it continues to move, and the hand setting works since that is another gearing that drives the canon pinion directly.

 

As it does run, it should just need a service. But the longer it runs in this state the more potential damage that can be done.

[vinn3]

Quote

 

   you realy need a photo when discussing that mvt..   I quit working on them years ago.   vin 

[JohnR725]

It's a standard problem for 218 watches. If you're not familiar with the watch you really should have the service manual if you're not familiar with the watch you probably shouldn't work on the watch. Page 30 of the PDF manual below shows the Canon pinion labeled as center wheel assembly.  Then it's also found on page 35 showing how it's lubricated just don't use their lubrication recommendation as it's a very poor choice.

Then before you rush out in order your canon pinions/center wheel assembly you'll have to take the old one out and measure the height.

http://www.decadecounter.com/accutron/Accutron218ServiceManual.pdf

[vinn3]

tuning fork watches a part of watch history - I hope !    mechanicly   and electricly   too complicated .   the case design - magnificent  I hope to find quartz movements to put all my cases (except the "space view ",   I keep it running.   vin