Component's function.

[fjseal]

This is a pocket watch of some age which I am having difficulty taking apart, and I don't know what the curved spring-like component is for. It appears to be attached with shellac. The shaped cut-out must be a clue, but otherwise I can't see what its purpose is. Any ideas please.

Best regards,

Frank.

[nickelsilver]

It's to unlock the cover of the movement. Shift it clockwise and you can take the cover off.

[JohnR725]

it's a safety feature to keep unauthorized users out of their watch. Unfortunately it doesn't prevent people from taking the screws out?  it looks like you're missing a few screws? The  The large missing screw is holding the balance bridge on so when you remove the cover be extremely careful that the bridge doesn't come off. Then it also looks like you're missing the two screws that holds the jewel assembly in place for the balance.

10 hours ago, nickelsilver said:

It's to unlock the cover of the movement. Shift it clockwise and you can take the cover off.

I prefer to think of it as a safety feature. then there shouldn't be any shellac it should just slide and the cover should come off if there is shellac that's not a good sign combined with the missing screws.

[fjseal]

It isn't shellac, it's rust. I have the screws so I can put them back in. It is a friend's watch and I think I should tell him it is beyond my capability/experience to be on the safe side. There is definitely a problem with the mainspring not increasing tension as you wind it.

Edited September 14, 2020 by fjseal

[JohnR725]

5 hours ago, fjseal said:

It isn't shellac, it's rust.

you should put the screws back in as now is not the time to have them out. Then try sliding and taking the back off just so we can see what's underneath. As that is rust and looked like rust more likely the entire movement is gone but you won't know until you take the back off.

5 hours ago, fjseal said:

I think I should tell him it is beyond my capability/experience to be on the safe side

rejecting a repair offers often times a good thing especially if there is sentimental value and definitely a good thing if it's not your own watch. It's hard to tell without the back off but if you're having mainspring issues there's a possibility that the fusee chain is broken. That is it has a fusee we can't tell that until the cover comes off.