Vintage Air King question

[David AP]

Allo all.

I've got a 1958 airking with the 1030 calibre movement from the explorer.

It keeps spectacular time, but seems a bit iffy on power reserve.

I wear it all day at work, and then take it off about 6.30pm when I get home.
It goes back on at about 6.30am the next day.

Sometimes it seems to run for ages without a prob and them one morning I'll get up and it's out of juice.
Is that to be expected or not?

It's had a recent service and a new timing spring but was the same before and after that.

Cheers.

[Bisquitlips]

This would be a mystery to me and doesn't make a lot of mechanical sense. There should be some stability to it, especially after having been serviced.

You should have at least a 40 hour power reserve I would think, but will stand by for the more experienced WIS's here.

[Tools]

I don't know how active you are, but here is my guess..

A self winding watch will run for it's maximum power reserve only if it is at it's maximum wind.. To test it's maximum power reserve, fully wind the watch and let it sit, untouched, until it runs down.

If we are not active enough during the day to fully top off the wind, it will slowly lose that percentage of power each day until it stabilizes at a point where the only wind in the watch is what you put on it during that day..

It's possible that your movements only put about 12 hours of wind into the watch each day.

Here are the other two possibilities..

. The mainspring is weak and does not hold the wind

. The bridal clutch that slips inside the mainspring barrel is slipping too much and not allowing the spring to be fully wound.

. I guess this is three....the mainspring barrel may be worn out and the clutch does not have sufficiently defined detents to stop the mainspring bridal from slipping.

[David AP]

thanks for the feedback chaps - appreciate it.
I'll do some winding experiments and see where we go.

Then I guess consider the bridal clutch.

Cheers,

D.