What is the purpose of the 'notch' in the swan neck regulator?

Hi all,

First of all, please forgive my lack of technical knowledge and for potentially screwing up the terminology.

Now to my question: What is the purpose of the 'notch' in the regulator of ALS watches? I have highlighted this notch in the following two images (copywrite "SteveG"):

Please note that in SteveG's photos the notch is dead straight. However, in my own watch the notch is crooked when viewed with a 10x loupe (which provides roughly the same apparent size as Steve's photo). That is to say my notch does not appear to be intentionally machined; rather, it looks like a cracked line, a geographical 'fault' in some rock so to speak. Maybe I'm crazy, but should I be worried?

I don't have a camera good enough to take a photo of my notch, but here is an artists impression:

So, to sum up:

1. What is the technical purpose of this notch?
2. Why is my notch 'cracked'? Should I be concerned?

And because no thread is complete without some actual watch photos, here is my 1815 Auf & Ab:

💰437 Marketplace Listings for A. Lange and Söhne›A. Lange and Söhne 1815 · 2 for sale · 4352 discussions›

I assume the "notch" makes it a spring

By: COUNT DE MONET : May 10th, 2013-23:32

I guess during assembly the notch will be opened a bit, bend a bit to put all into place and to hold it securely after wards. There is nothing wrong with your lovely Up and Down ... a very nice 1815! Best Moritz

Hi Moritz,

By: Crescendo : May 11th, 2013-21:10

Thanks for your reply. It's interesting what you say about it being a sort of spring, or a least a means to widen and loosen the part to allow for fitting. It makes sense. It would be nice if an expert could confirm or deny this. :) Thank you also for the...

Ok, ok: YOU asked for technicalities :-)

By: COUNT DE MONET : May 12th, 2013-01:41

The whole thing is called swan neck regulator. On the first pic you see the lever pointing to the left. The little screw in the bottom will move the lever (called "Ruecker" in German) up if you crew in and down if you crew out. This movement has also on i...

Uh oh, I'm a little confused now. :)

By: Crescendo : May 12th, 2013-06:03

To be clear, I do understand that the regulators in ALS watches use swan necks, and I do know what a regulator is for (it adjusts the effective length of the hairspring). However, I don't understand what you mean by this: "This movement (of the lever) has...

Since I am not a Lange technician ...

By: COUNT DE MONET : May 12th, 2013-08:36

... I had to go into the text passage again to read about it. The whole swinging system is made out of several pieces that have to be assembled together. The notch in the regulator part will be like a spring as the component with the pins holding the bala...

Thank you!

By: Crescendo : May 12th, 2013-09:11

Moritz, thanks for your patience in explaining and confirming the function of the notch to me. Much appreciated. I have looked at my watch's notch again with the 10X loupe and it is definitely crooked/jagged around the edges (like in my artists rendition)...

Dr Monet's advice: look at other close ups here

By: COUNT DE MONET : May 12th, 2013-09:50

Simply enter " Lange close up" into the Forum Search function here and tick "images" first. You will see: it is all fine, all of them have got it. I could see it even with my bare eyes in my 1815 homage moon phase! One more interesting note: if you compar...

Oh yes, I understand that all the watches have the notch...

By: Crescendo : May 12th, 2013-10:49

...I don't dispute that, it is plain to see in many photos of ALS watches. However, if the notch is supposed to be straight and well-finished, as it seems to be in SteveG's high-res photos of both his 1815 and L1, mine is not. Mine is cosmetically damaged...