International Watch Co. Schaffhausen Mainspring limiter

aalinaman

Registered User
Oct 8, 2012
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I have, what I believe to be, a IWC Schaffhausen Silver Pocket watch Cal. 53. It Has what seems to be a mainspring limiter on the mainspring arbor and barrel. With this limiter on I can only get about four winds on the mainspring. Does anyone know the purpose of this limiter? Any information would be appreciated. I have included pics.
IWC Cal 53.jpg IWC Schaffhausen.jpg Maispring Limiter.jpg
 

gmorse

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Jan 7, 2011
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Hi,

This is known as "Geneva stopwork", and it prevents the spring from being used at both extreme ends of the wind, in an attempt to provide more even power delivery. It sounds as though it's working as designed.

Regards,

Graham
 

DaveyG

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Mar 21, 2005
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You should still get the nominal 30hrs running from the watch. It is nice to see the watch with the Geneva stopworks still present and functioning as they were often disabled by removal of the finger wheel in later years when the mainsprings manufacturing process became capable of producing the springs with more accuracy and consistency making the springs more able to function correctly at their extremities.
 

Dr. Jon

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Dec 14, 2001
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If you are getting only four turns the stop is no adjusted properly. It has 5 leaves and should allow about 5 1/2 turns. Wiht a good mainspring it should be set up to that the first click is enought to start the watch and then it ahooud allow 5 1/2 turns..

Even modern mainsprings do better with one of these in palce and working properly.
 

DaveyG

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Mar 21, 2005
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Dr Jon is absolutely correct in what he says. One of the problems with this system is that maintainers today either do not know how or do not bother to set up the stop works properly and yours seems to be a case in question. However, although not set up correctly it does seem that you should get more that 4 winds from the condition it is currently in, assuming that the power is fully let down on the watch.

If you observe the 'Maltese Cross' element of the stop works you will note that 4 of the leaves have concave machining on the end whilst the 5th is convex. When fully powered down the finger wheel should be hard up against the convex portion on one side and when fully wound hard up against the convex portion on the other side. If you wind the watch with the stop works visible you should be able to watch the stop works in operation and see whether this is the case or not. If the finger wheel does not meet the convex portion of the Maltese Cross wheel it would suggest that the mainspring fitted is too short (or just possibly much too long) so reaches the fully wound condition before it should.
 

aalinaman

Registered User
Oct 8, 2012
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Thank you for all the great information. It is wonderful to have such a site that is so full of knowledge.
 

Squite

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Jun 26, 2012
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Agreed. I have a small ladies' watch with a Maltese Cross, and whilst I already had pegged the gist of it's purpose, I also found the above information quite helpful as well.
 

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