Peseux 7040 - Cannon pinion too loose

VWatchie · December 2, 2024

I serviced this Peseux 7040 at the beginning of the year with good results. I haven't used it much, but since the dial gives me a little Christmas feeling, I thought it might be nice to wear now that it's getting closer to Christmas.

When I set the time, I found that the crown gave far too little resistance and thought it would be fairly easy to fix. So, I took the watch apart and found, to my surprise, that the cannon pinion had no dents. In addition, the cannon pinion is unusually thick and hard, and the arbor of the centre wheel is relatively thin.

The question is if and how I can increase the friction between the cannon pinion and the centre wheel.

mikepilk · December 2, 2024

That looks odd. All the pics I've seen of a 7040 show a 'normal' pinion with indents. It looks like it should pull apart

nickelsilver · December 2, 2024

That looks like a cannon pinion that has perhaps cracked and been repaired by sleeving it. I think they made a tube that fits between the pinion and the upper seat for the minute hand; no way to adjust it now. A new CP should be easy to source.

VWatchie · December 3, 2024

On 12/2/2024 at 11:43 AM, mikepilk said:

It looks like it should pull apart

On 12/2/2024 at 11:49 AM, nickelsilver said:

I think they made a tube that fits between the pinion and the upper seat for the minute hand;

You were absolutely right, so thank you very much! The manufacturer needed to make the CP thicker to accommodate the gear that drives the hour hand and date hand on this regulator watch.

I managed to split the tube and the CP by prying with hand levers, at least a bit. Then I attached the tube to a vice and pulled the tube off by holding the CP with brass tweezers.

Then, it was just to adjust the CP's friction as usual, which in itself can be quite difficult. The friction got an ounce too big, but that's better than the CP not rotating or rotating only sporadically, as in my case. At some point, I'll try to reduce the CP friction in the way @nickelsilver described in this post .

To reattach the tube to the CP, I used my staking set and a concave punch. I almost managed to get the tube on by hand alone, but to get the tube down the last little bit I tapped very gently with a brass hammer.

I kept a small gap between the tube and the CP because it looked like that when I pulled the tube off, but also because there is a washer against the CP that I assume should fit in the gap (without really understanding why it would be needed or if it was intended).

After this, it was just a matter of reassembling the parts and the watch is now sitting on my wrist doing its thing, ticking away to Christmas day.