Help determining part name?

[MyFavoriteObsession]

Hello, I am working on an AS 1320 (Bulova 10BRC, 9AS) automatic movement and have found it to be missing a part for which I cannot find a name. I have looked at the 10 BRC automatic assembly parts list and the parts list for the movement itself and still cannot locate it. Here is a photo with the missing part outlined in red.

It is a spring-like device that prevents the automatic assembly's third winding wheel from engaging the ratchet wheel when the mainspring is fully wound. If anyone could tell me the name of this part so I could order a few replacement parts, I'd really appreciate it!

 

[oldhippy]

Can you post the link to the parts list or up load the list please.

[vinn3]

25 minutes ago, oldhippy said:

Can you post the link to the parts list or up load the list please.

I rember the part name list.    haveing a hard time finding it !    i'll keep looking.     vin

[Walsey]

Is it the "stop click"?

https://www.ebay.com/itm/AS-1320-CERTINA-21-014-PART-1428-NOS/123741348195?hash=item1ccf8f2163:g:N1kAAOSwEVZaW2ql

[MyFavoriteObsession]

54 minutes ago, oldhippy said:

Can you post the link to the parts list or up load the list please.

Hello, I used the Bulova Self-Winding Watches booklet (pg 18) and the '52 Catalog of Interchangeable Parts (pg. 79) to attempt to identify as many parts as I could. 

 

15 minutes ago, Walsey said:

Is it the "stop click"?

https://www.ebay.com/itm/AS-1320-CERTINA-21-014-PART-1428-NOS/123741348195?hash=item1ccf8f2163:g:N1kAAOSwEVZaW2ql

I don't believe that is the part but thank you.

[watchweasol]

Hi Attached is the AS 1320 tech sheet you should be able to find it on there I hope     cheers

AS 1320,1323.pdf

[MyFavoriteObsession]

8 minutes ago, watchweasol said:

Hi Attached is the AS 1320 tech sheet you should be able to find it on there I hope     cheers

AS 1320,1323.pdf 1.63 MB · 1 download

I can't thank you enough, Watchweasol! Within one minute of opening the file, I found the part is called a "Breguet spring". Thank you again!

[oldhippy]

Thats right chaps well done all. 

[watchweasol]

Hi  My pleasure glad to be of assistance   good luck with the repair.        cheers

[GuyMontag]

Plot twist, the Bulova 10BRC doesn't use the Breguet spring! Although it's based on the AS 1320 the Third Winding Wheel is constructed differently and the spring isn't used. The 1950 'Bulova Self-Winding Watches' manual shows how the automatic works functions and lists all of the parts. They also latter released an addendum to clarify the recommended oiling in the 1952 Technical Bulletin No. 2 (attached).

Bulova 1952 Self-Winding Technical Bulletin No 2.pdf

[AndyGSi]

23 minutes ago, GuyMontag said:

Plot twist, the Bulova 10BRC doesn't use the Breguet spring!

Strange how it's on the parts list then?

[GuyMontag]

3 minutes ago, AndyGSi said:

Strange how it's on the parts list then?

I saw that and thought the same. I believe it's an error. I have two of the 10BRC and neither have that spring. I've looked at a number of the 10BRC movements on the web and can't see the spring. The Bulova parts list and description of how the automatic works functions does not mention the spring either in the parts list or when describing how the automatic works functions. The lubrication recommendation does not mention lubricating that spring, while the AS 1320 technical documentation does.  I believe that the different construction of the Third Winding Wheel in the 10BRC compared to the AS 1320 is why Bulova did not include the spring.

[AndyGSi]

2 hours ago, GuyMontag said:

I saw that and thought the same. I believe it's an error. I have two of the 10BRC and neither have that spring. I've looked at a number of the 10BRC movements on the web and can't see the spring. The Bulova parts list and description of how the automatic works functions does not mention the spring either in the parts list or when describing how the automatic works functions. The lubrication recommendation does not mention lubricating that spring, while the AS 1320 technical documentation does.  I believe that the different construction of the Third Winding Wheel in the 10BRC compared to the AS 1320 is why Bulova did not include the spring.

So is that just an empty space on the 10BRC?

[GuyMontag]

11 minutes ago, AndyGSi said:

So is that just an empty space on the 10BRC?

Yes, it has a cutout for the Breguet spring (photo), the screw hole and the steady pins but no spring. The pinion on the bottom of the Third Winding Wheel on the Bulova is solid with the wheel and engages with the Ratchet Wheel. On the AS1320 it has a clutch wheel that can slip and disengage from turning the wheel when the watch is manually wound and it needs the spring to keep it engaged with the wheel. I'm not sure why this is necessary as the the auto works will also disengage from winding the rotor when the movement is wound because when it is wound the alternating disc rotates away from the rotor.

That Technical Bulletin I posted above doesn't come out and say it but it sounds like this setup with the Bulova might be a design issue:
 

Quote

Whenever the click becomes inoperative, another serious possibility is a broken third winding wheel. This can result as the stored up power of the mainspring is released against the pivots of the third winding wheel before the main click snaps back into the ratchet wheel.

Another cause of breakage of the third winding wheel can be due to excessive resistance of the safety in the mainspring barrel.
 

Perhaps not having that slipping clutch (a cost saving measure?) leads to problems with the Third Winding Wheel breaking.