What does this part do?

[Stian]

Hi guys,

In the middle of the picture there is a small part held with one screw, partially covering the hole for the center wheel. This part stops the center wheel from going fully into the hole, but also lifts the train bridge up, so much that the escape wheel doesn't fit well into its pivot holes. This is from a vintage GUB Glashutte watch.

Does anyone have experience with this type of part? I've never seen anything like it and it really puzzles me.

Thanks for any help,

Stian

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[Geo]

First I must confess that I've never seen one of these before.

Remove the screw and the small plate and see if the centre wheel pinion protrudes through as it should.  If it does protrude, it may have an a grove in it in which the plate will sit.  If it does, replace the plate and tighten the screw.  It might be a strange method of eliminating end float of the centre wheel.

This is only a guess.

[ramrod]

could it be a chaton for holding the jewel?

[Marc]

It's not an uncommon set up in either Swiss or Russian movements although I usually encounter whole plates rather than partial plates and they almost always sit into a machined recess so that the thickness of the bridge isn't increased, and I have even seen them jewelled. Below is a Felsa 465 showing a more complete execution of the same set up. As to function I think that Geo is probably right; it limits end shake on the centre wheel.

The screw that holds it in position though is usually counter sunk allowing the screw head to fit flush with the plate. On yours it looks like a standard screw head. Take the screw out and have a look at the hole. If the hole is counter sunk then it suggests that someone has replaced the original counter sunk screw with a less than appropriate one and that is causing your clearance issues.

[oldhippy]

The small plate in your picture shows it to be off center, in order for it to work properly it needs to be dead center. It acts as a spacer so the wheel has the correct depth in the train, sounds a bit crude but in your movement that's what its fore. I think its a bad design, but you come across many mad and bad things in watches.

[Stian]

Thanks a lot, guys for your help as always!

Stian

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[rogart63]

 

16 hours ago, Geo said:

First I must confess that I've never seen one of these before.

Remove the screw and the small plate and see if the centre wheel pinion protrudes through as it should.  If it does protrude, it may have an a grove in it in which the plate will sit.  If it does, replace the plate and tighten the screw.  It might be a strange method of eliminating end float of the centre wheel.

This is only a guess.

Think you are spot on there? Remove and fit the center wheel. There should be a groove in the center wheel?   

[Stian]

There's no groove in the center wheel, and this little piece keeps the train bridge too high. The escape wheel does not fit into its pivot holes, it's of by one mm or so. It's just very odd, as the watch was running before.

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[Marc]

Is it the screw that is fouling the train bridge?

Did you check to see if the hole is counter sunk?

[Stian]

It is the screw, yes, and it is not countersunk

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