Reply With QuoteI'll take note not to wind no more than 30 time on a few Eta's I have.
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A common fault with ETA 2824 and 2836 movements is sticking reversers. When this happens the hand-winding becomes tight and the rotor spins, if both reversers lock up and the determined owner continues to wind the crown something has to give and it's usually the teeth on the ratchet wheel that break. One of the odd features of this movement is the disparity between the crown wheel and ratchet wheel, the crown wheel has much larger teeth compared to the ratchet wheel, which seems odd, provided there are no problems all will be well for many years but the reversers are prone to sticking eventually. However, this fault can afflict quite new movements, don`t understand why but I`ve seen it happens a few times.
Here's a an example, a watch I`m currently fixing which came in with hand-winding issues. A combination of an owner determined to wind the watch (despite it feeling very wrong) aided by a big chunky crown resulted in a stripped ratchet wheel. Here's a pic of the damaged one (right) and the new replacement:
Here's a few pictures to show how the auto-winding and reversers work. The auto-winding bridge and rotor sit on top of the movement, the whole assembly is easy to remove:
The reversers consist of two wheels sandwiched together with a pinion attached to one wheel. In this application the reversers are both different, combined together they allow the rotation of the rotor to transfer motion to the ratchet driving wheel in one direction, the ratchet driving wheel can only move one way and the pinion in the centre engages with the ratchet wheel to wind the mainspring when the rotor moves either way.
There are various schools of thought regarding lubrication of ETA reversers, but the official method involves use of a special lubricant called Lubeta 105. The parts are immersed in the fluid which is a solution of lubricant in a solvent. Excess solvent is blown off and the wheels are dried to evaporate the solvent away, leaving a thin film of lubricant. The reversers contain tiny ratchets that allow the two wheels to move relative to each other in one direction only, it sounds far more complicated than it is.
The next picture indicates where the ratchet driving wheel pinion engages with the ratchet wheel when the auto-winding is replaced, it's also clear to see how the crown wheel drives the ratchet wheel during hand-winding.
When the watch is being hand-wound the one wheel on each reverser rotates rather quickly and the rotor should stay static, the hand-winding action should feel smooth. When the watch is fully hand-wound (approx. 30 turns on these) the mainspring will slip around the inside of the barrel walls in a controlled incremental manner, if all's well a faint clicking can be heard as the spring slip from one indentation in the wall to the next.
The advice I give to anyone when winding a watch is straightforward; if it feels wrong STOP! Fortunately the replacement parts are cheap and readily available for the ETA 2824 and Sellita SW200.1, the auto-winding can be serviced without stripping the whole watch, but if the ratchet wheel's lost some teeth they have to be somewhere and in such cases I always strip the movement completely......sods law states that the fragments of broke tooth will cause problems eventually!
With the auto-winding re-installed it's a simple task to move the rotor back and forth to check that the motion is being transmitted to the ratchet wheel, which can be observed to move very slightly during each oscillation of the rotor. If all's well the watch will self-wind correctly and the owner will be happy.
I'll take note not to wind no more than 30 time on a few Eta's I have.
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A cracking post. Helps me understand how these miniature marvels actually work.
Thank you Paul for the pictures, the detail and the explanation.
Winding more than 30 times won't do any harm provided the movement isn`t suffering from the fault I`ve described, but on a 2824, Sellita SW200 or ETA 2836 30 twists of the crown is enough to fully wind the spring. However, the ETA 2892 is significantly different, the hand-winding is lower geared and these take approx 65 twists to fully wind. Another big difference is the reverser, this movement uses only one but that is also prone to sticking. When that one sticks the watch hand-winds OK but won't auto-wind despite the fact that the rotor moves freely.Originally Posted by sickie
I love threads like this, I have heard about this issue but have to admit I didn’t really understand the actual problem until now. Thanks
Great post Paul.
I have a similar issue on a Tudor Prince Oyster Date 9050/0, but believe the watch has an ETA 2784.
Would this be something you would be able (or willing) to take a look at for me?
Watch is running well & keeping good time, just feels like it turns the rotor when hand wound (which I stopped doing when I first noticed the issue!).
Honestly I very much appreciate all this advice.
Any suggestions on the ETA 2893-2?
This really is by far one of the more useful post's I've seen in a while. No offence to anyone on the forum intended.
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2893 is based on 2892, should be around 60-65 twists of the crown to fully wind.
OK thanks
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Teaching is an art, you've got it. Thanks for the clear advice and explanation and pics. Much appreciated. Monthly lessons?
thanks for sharing this. Learnt a fair bit.
As a rule for my few autos i wind them just a few times and give them a shake and wear. Perhaps a habit from my early days of owning a 7s26 as my first auto.
thanks for taking the trouble to show this.i now understand how how the winding gears work and also how the automatic winding works.
My legend diver does this i think it has this movement in it, will a basic service cure it?
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Great post - absolutely fascinating. Thank you.
Likewise.
Great post Paul and as you said it can happen at any stage, even brand new movements very occasionally suffer from locking reversers in my experience. Thankfully cleaning and then Lubeta 105 usually sort out the problem.
Hopefully posts like this make us appreciate what fantastic little mechanical marvels we wear.
Cheers,
Gary
Superbly informative as always - I really appreciate these types of posts. Thank you Paul.
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I have a CWC Mellor 72 which has a Sellotape 210 movement. Upon receiving the watch I wound approx 30 turns and stopped when it felt the crown was slipping back. However, the watch would stop dead at or near 24 hours. CWC advised to continue until the crown could not be turned, approx 40-45 turns. It has resolved the issue but reading this unsure if I should stick with 30 or 40-45 turns.
Those sellotape movements are notorious for being sticky. (Sorry!)
Really enjoyed the read, very informative and definitely relevant for many!
Would love explanatory posts with pictures like this on movements more often!
Beat me to it
Hand-wound movement, totally different!
Great post Paul as always! Perhaps another topic could be on the theory of rate variability and low mainspring tension?
“ Ford... you're turning into a penguin. Stop it.” HHGTTG
Always enjoy reading your "how it works" posts Paul.
This one has explained why one of my watches is so difficult to wind.
Look forward to reading more of your informative threads!
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Very useful post, thanks Paul for taking the time to explain this.
I’m always up for learning so posts like this are very welcome and a nice change from the norm.
Enlightening thread, particularly as not that long back I bought then returned an old Sewills with the eta 2824 movement off the bay, which on receipt didn't run contrary to the description. Also found I couldn't wind it properly either as the crown would rotate quite freely anticlockwise but it was completely solid going the other way.
Sounds like the sticking reverser problem.
Simple reason why the crown would rotate anti-clockwise. The stem drives the sliding pinion which engages with the winding wheel via Breguet teeth which engage in one direction only and slip against each other in the opposite direction.
Here's an example from a Miyota 9015 I`m servicing at the moment:
When the crown is pushed home both parts are held in contact by the yoke and spring (not shown), the stem engages in the sliding pinion via a square section so when the crown is turned the sliding pinion will rotate. In the clockwise direction the teeth will drive the winding wheel which connects to the crown wheel and ratchet wheel, thus winding the mainspring. If the crown turns anti-clockwise the Brequet teeth slip against each other and that causes the characteristic clicking that you'll feel (and hear) when the crown is turned this way.
When the crown is pulled to handset position the sliding pinion moves away from the winding wheel and the opposite set of teeth engage with the setting wheel to set the hands. These teeth are conventional so the hands can be driven in either direction.
Problems can arise when the Breguet teeth on the sliding pinion and winding wheel get damaged and chipped on the tips, they will fail to engage strongly and the watch won't wind properly. This is characterised by a slipping/clicking experienced when the watch is approx. half-wound and the mainspring is getting harder to turn. This fault can be caused by the stem being fractionally too short, a fault at manufacture that can manifest itself later in the watch's life. On older watches it can be caused by excessive wear to the mainplate, often due to the stem being poorly aligned because the movement isn`t siting correctly in the case or a replaced pendant tube not being quite perpendicular to the case. Lack of lubrication exacerbates these issues.
Thank you WW!
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