Landeron 48

[Specializedjim 4]

Hi all and happy Christmas. 
I have just completed a Landeron 48 movement re commission. I have the watch now working well, in balance and keeping good time. However the only problem I have is when I alter the time the balance jams. I’m not sure of the correct terminology but it looks as if the impulse jewel gets the wrong side of the pallet fork and then can’t get back and the balance is then jammed. 
Is this a common fault that I’m just not familiar with? Many thanks for any help. 

[Poljot 274]

30 minutes ago, Specializedjim said:

Hi all and happy Christmas. 
I have just completed a Landeron 48 movement re commission. I have the watch now working well, in balance and keeping good time. However the only problem I have is when I alter the time the balance jams. I’m not sure of the correct terminology but it looks as if the impulse jewel gets the wrong side of the pallet fork and then can’t get back and the balance is then jammed. 
Is this a common fault that I’m just not familiar with? Many thanks for any help. 

Here is the link if you do not have it yet (to improve terminology if needed)

https://www.cousinsuk.com/PDF/categories/1471_Landeron 48.pdf

[Specializedjim 4]

Any help appreciated. 

[Tudor 391]

Perhaps the impulse pin is not straight? How does that look?

How much does amplitude drop when the chronograph is started?

[Klassiker 160]

Definitely not a common fault. What you seem to be describing is called "overbanking" or "out of action". One possible cause is a bent guard finger. Another is an out of place safety roller. Yet another is worn balance- or pallet-jewels (or worn or bent pivots) which affect the interaction between finger and roller. What is puzzling is why the problem only occurs when you are setting the time, and why the watch otherwise funtions OK.

[JohnR725 1,359]

I have a link to a video that explains what the problem could be. Then when you're watching the video he shows explains basically a test which you're supposed to be doing on all your watches to verify the safety features are working. But typically on wristwatches no one ever does this because typically they work.

1 hour ago, Klassiker said:

What is puzzling is why the problem only occurs when you are setting the time, and why the watch otherwise funtions OK.

When you look at the video typically when all the safety features are in place that should never happen. If they guard pin is not functioning and you receive an external influence like a bump the pallet fork will move. In setting the watch it's possible to put enough pressure on the gear train stop to gear train which would allow the pallet fork to free float and move. Of course this is not a setting problem this is a safety problem.

It would be nice to see a picture of your pallet fork because looking at the parts list I can guess on something. Another thing that can happen to the guard pin on older watches are the guard pin is adjustable. They even make a tool so you can push it in and out as it's a separate round pin. It's possible that it has relocated to someplace it's not supposed to be.

It would be really nice to have a picture of the balance wheel out of the watch and the pallet fork still in the watch but a good picture the pallet fork aimed at the guard pin area as that's more than likely were your problem is.

https://youtu.be/DxeM85XRTbU

[watchweasol 1,462]

Hi As a further aid to terminology  and understanding  see the attached documents for your perusal      cheers.

TZIllustratedGlossary.pdf Witschi Training Course.pdf

[Specializedjim 4]

Hi all. Many thanks for your assistance and educating me on something I didn’t fully understand. The overbanking theory I think was correct as I have changed the pallet fork and now it appears that the impulse jewel does not get on the wrong side. Many thanks for all of the advice it was very much appreciated.