Service: Longines Automatic calibre 340

IMG_2129This Longines that Stuart sent in has an unusual rotor for the auto winder – so I thought I’ll share a look at this movement with you.IMG_2057

And here is the calibre 340 in all its beauty. The rotor is mounted on a wheel that goes around 360 degrees, which in turn drives another wheel. That takes the gear ratio of the auto winding mechanism right down, and is an unusual design – probably not cheap!IMG_2059

The movement needs some attention, as the amplitude is pretty low.IMG_2134

The bottom plate is a nice sight indeed. The see saw construction of the intermediate winding/setting wheels reminds a bit of a pocket watch.IMG_2136

The unusual rotor with its bridge.IMG_2142

The wheel train. The solid wheel at the bottom is the one that the rotor wheel engages with to wind the movement.IMG_2148

The barrel is a sealed unit. I can’t find a new one, and the old one seems to be in good condition, so I will leave it in.IMG_2150

The centre wheel is set in its own cock. IMG_2152

The bottom plate wasn’t cheap to construct, either. Looks like money wasn’t too big a consideration when this movement was designed.IMG_2156

The cap jewels are translucent, and I’m not a big fan of that. They are easy enough to lose if they are ruby coloured …IMG_2157

For a movement without a date, there is no lack of parts!IMG_2187

As usual, I put together the base movement first.IMG_2427

I now have a decent amplitude. There is a bit of wear in the movement, and I blame the slightly jagged graph on the escape wheel / pallet fork. Still good for the age of the movement, though.IMG_2191

The bottom plate ready for dial and hands.IMG_2426

With a new crystal, the watch looks as good as new.

11 thoughts on “Service: Longines Automatic calibre 340

  1. Hi Christian, A customer brought one of these into my shop, saying it was not working corrector. I discovered that one of the ‘movement clamps’ came loose (the screw backed out all the way). I found the screw and… after some close inspection the ‘clamp’. it’s wedged in the escape wheel (arrgg). No way to remove it (in-situ) without damaging the wheel, so I need to disassemble the train (removing the bridge) to get it out safely.
    Question: how do I ‘remove’ the mainspring power? I attempted to move the click (while hold the crown) (as typical on a manual movement) but some automatics have an ‘additional’ click to keep the mainspring from unwinding while the rotor is winding. where is this 2nd click?? It would be a disaster if I removed the balance, then pallet bridge and fork with mainspring wound. YIKES.
    any assistance on this would be most welcome.

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  3. I bought my Longines Calibre 340 stainless steel with date in 1968.
    I would like to get it repaired but my watch repairer says it can’t be done in Western Australia due to lack of parts.
    Is the watch worth repairing? and is so where can I have it done?
    Mary Ashby

    • Hi Mary,

      We can do that for you. Please try to get a repair slot from our booking page – we give those out every 3 weeks or so.

      Best regards,


  4. Christian, a fantastic job, thank you very much – I bought the watch for the dial, but am blown away by the engineering inside as well… Now if only it wasn’t a sealed barrel…

  5. Lovely watch, inside and out!
    The venus 170 chronograph I just serviced has the same ‘see/saw’ lever (or ‘rocking lever’ as it says on my parts list 🙂 ) as this movement. The finishing detail on the base plate isn’t as nice as this one though!

    Another good job Christian.

  6. That’s a really smart looking movement, and a really smart looking watch!

    Bidfun mentions “optionally, probably always with 5 ruby balls (not included in jewel number, cf. Longines 345)”… but the ones on this movement look to be steel to me 😉

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