Strange Vostok behaviour after casing.

[Simeon]

I recently serviced a spare Vostok 2209 movement to swap into my 80's Amphibia. The movement cleaned up OK and I swapped in a replacement sweep second pinion from a donor as the Rio had been broken off this movement. I ran it all day and tested it on my timegrapher. 270 degrees DU and DD (with the old mainspring) and running about -30 secs in each position and about -50 in the vertical positions. I was quite happy with this so I regulate it to about +18secs DD to even out the average and figure I can wear it for a while to see how it goes on the wrist. 

I uncase the old movement from the watch, remove the hands and dial and swap them all over to the serviced movement. At this point I notice that the amplitude has dropped off massively and the rate is now+600 secs and if I turn the hands backwards it stops the balance. The 2209 has a relatively unusual layout with an indirectly driven cannon pinion, driven through a cutout in the main plate by one of the wheels along with a 'double third wheel' which applies tension to the seconds pinion while driving it. When I wind the hands forward the balance picks up pace again before slowing down.  I took it back out the case and have removed the hands and cannon pinion again and it is still running with low amplitude so I think the problem is further back in the train.

I think I managed to damage the train somehow when installing the hands (perhaps turning them backwards via the cannon pinion when nudging the hands around?). The second hand also jumps around when setting backwards so it looks like an issue with the double third wheel. I serviced a 2234 a few months back (a 2209 with calendar and hacking) and had problems with a warped double third wheel causing erratic running. 

Before I jump back in and strip the watch down again, does anyone have any idea what may be causing this and how I might have done it?

[nevenbekriev]

What You describe - that the second hand jumps when setting hands backwards is normal for this layout of train with double third wheel. Happens when the real cannon pinion(which is on the offcenter 2nd wheel) is tight. Pay attention exactly on this cannon pinion - probably somehow it has moved up on the wheel pivot and thus killing the axial free play of the wheel and rubbing on the bearing in the main plate

[Simeon]

I didn't realise that the pinion on that second wheel was loose to act like a cannon pinion. That would make sense I suppose as it is like the setting is firmly connected with the train.

While I know some people 'hack' this movement by holding the setting backwards to stop the movement while they wait for the full minute, I have never seen it so dramatic that it stops the movement completely, needing a shake to start it again on a 2209.

How loose does this pinion have to be? Would I be better swapping this for a spare?

[mbwatch]

1 hour ago, Simeon said:

How loose does this pinion have to be? Would I be better swapping this for a spare?

Do you mean to say yours is too tight? That is the good problem to have, and you can possibly add a tiny bit of heavy oil. Usually they are worn out and way too loose causing timekeeping loss in the hands.

[Simeon]

3 hours ago, mbwatch said:

Do you mean to say yours is too tight? That is the good problem to have, and you can possibly add a tiny bit of heavy oil. Usually they are worn out and way too loose causing timekeeping loss in the hands.

Well, I have serviced a couple of these movements now and never noticed that the pinion is rotating free compared to the wheel, certainly not freely spinning. I have never tried to rotate it so not clear what the breakaway torque might be. I am guessing that the one on my movement has locked up, hence the dramatic effect when I set the hands and the drag on amplitude. 

[nevenbekriev]

Need to say that replacing cannon pinions is normally connected with need of adjustment of the tightness. No guarantee that just replacing it will solve anything, as it fits well on one 2nd wheel, may not fit well on another, and this is normal. So, if the pinion is not broken or destroyed in some manner, it needs just adjustment of the tightness.

One needs to have correct feeling about the tightness. Too much will cause problems as  excessive wear and even teeth breaking on the wheels. Not enough will cause irregular stopping of hands movement. For sure, some resistance must be felt when setting hands. But, 'hacking' normally should not happen if the main spring is wound to the end. 

Tightening must be done correctly as to ensure the pinion will stay on it's place and will not come off (up) when rotated, not only correct tightness is needed.

2 minutes ago, Simeon said:

Well, I have serviced a couple of these movements now and never noticed that the pinion is rotating free compared to the wheel, certainly not freely spinning. I have never tried to rotate it so not clear what the breakaway torque might be. I am guessing that the one on my movement has locked up, hence the dramatic effect when I set the hands and the drag on amplitude. 

So, You never took cannon pinions off to clean and then lubricate them? This is wrong, as blocking may happen without lubrication.

[Simeon]

OK, I fixed it (sort of).

I have the amplitude back up to 270 degrees but I'm not entirely sure what I did. Firstly I removed the balance and pallet fork and gave it a wind to see how the train looked. The train looked good, running free with a little rebound at the end. I put the balance and pallets back in and got it started. Better - about 200 degrees amplitude but still prone to stopping when setting the time anticlockwise. I then pulled the barrel bridge to get access to the second wheel that drives the minute pinion / cannon pinion and connects with the intermediate setting wheel through the hole on the main plate. 

I also took a good look at the second wheel and tried turning the wheel against the bottom pinion. It turned but not easily, so I worked that in place and pressed some oil into the pinion where it projects through the wheel. I tried removing the wheel from the pinion (as @nevenbekrievsuggests) but this is firmly stuck in place with no endshake against the pinion.  Ir doesn't feel like it can come apart for cleaning and lubrication.  Not sure what should be done to properly service this (I didn't want to pull too hard in case I distorted the second wheel.  I compared it to the same wheel from a donor and it was exactly the same, in terms of friction and being unable to remove the bottom wheel. I reinstalled it back in the movement and replaced the barrel bridge, pallet fork and balance. The movement fired up again with 260-270 degrees amplitude. It's not quite as good as it was previously but it now doesn't stop when setting the time anticlockwise (it seems to slow a bit but keeps running)

I will carefully recase it tomorrow night with no wind in it to stop me from turning the minute pinion (and this wheel) against the train rotation since that's what I think I did to 'break' it.