# Seiko Chrono Query 6138 / 6139



## 036 (Feb 27, 2003)

This goes against what I had previously thought:

Seiko forum thread

Written by Greg Heath on the above forum:



> For the 6138/6139 movements, there is less wear when the chrono' is running, so it is better to keep the chrono' running most of the time, which of course gives you a second hand that you can use to time the watch with.
> 
> The top pivot is jewelled. When the chronograph is switched off, the movement runs on the bottom pivot (dial side) which runs in a bronzed bushing. When the chronograph is running, the movement runs in a jewel underneath the 4th wheel and there is less wear on the movement.


If that is right does it only apply to these movements?

Simon


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## Stan (Aug 7, 2003)

That might suggest a poor design in the first place.









Maybe with a pinch of salt?


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## 036 (Feb 27, 2003)

Not sure I am with you there Stan?

I am starting to realise these Seiko chrono movements designed not long after the Swiss came up with the first auto chronos have a lot going for them.

Certainly my Bullhead performs at least as well as my Swiss auto chronos: Heuer cal 12, Omega cal 861... Kelek...


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## Stan (Aug 7, 2003)

Sorry if I read too much into it Si.









"For the 6138/6139 movements, there is less wear when the chrono' is running, so it is better to keep the chrono' running most of the time, which of course gives you a second hand that you can use to time the watch with.

The top pivot is jewelled. When the chronograph is switched off, the movement runs on the bottom pivot (dial side) which runs in a bronzed bushing. When the chronograph is running, the movement runs in a jewel underneath the 4th wheel and there is less wear on the movement.

Leave those old chronos running!"

Why would Seiko design a watch that will wear out more quickly under normal funtioning than running under a complication?

Can't see the sense in that.









I could know "bugger all" of course.


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## 036 (Feb 27, 2003)

> Why would Seiko design a watch that will wear out more quickly under normal funtioning than running under a complication?


Valid point actually Stan.

I was not so much thinking which design is best but more along the lines of "what is the best thing to do with different chronos, run them or not".

But maybe Seiko thought, as there is no continuous seconds on these chronos, that most buyers might prefer to run them all the time? Certainly if I thought it would do no damage I would prefer to have the chrono running on any chrono without a continuous seconds.

In other words maybe Seiko thought that for most users, normal functioing would be to have a second hand moving around the dial.

If I was convinced about this I would just let my Bullhead run: it looks better, and let's face it I have never ever used any of my chronos to time anything!


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## Stan (Aug 7, 2003)

Si,

This point would worry me with a Seiko.









I would run the watch as per the instructions that came with it.









Yes I would trust Seiko because they are a sound manufacturer. I don't think they'd hide any serious short comings from anyone.

I have a lot of time for Seiko, no pun intended.









But, who knows how Seiko was thinking at the time?


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## raketakat (Sep 24, 2003)

Si said:


> In other words maybe Seiko thought that for most users, normal functioing would be to have a second hand moving around the dial.


 Thats the way I see it too. I'm not a chrono. fan. I only have a few but when I wear them I always have the second hand running.

Is that not normal







?


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## Stan (Aug 7, 2003)

I love the quartz ones.









Coat almost on.


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## Silver Hawk (Dec 2, 2003)

Interesting subject....but this is all relative isn't it?









I have a bunch of 6138 and 6139, they must all be at least 30 years old and I'll bet nothing has been done to most of them other that fix a stuck pusher, a clean and a quick lube (as our American cousins put it)....yet, they are my best time keepers (







says more about my other watches maybe







)

So are we saying a pivot/jewel might wear out without chrono running in about 100 yrs versus 110 yrs with chrono running? If so, I'm not too worried









I seem to remember another thread ages ago asking whether a manaul chrono watch would run down fast with the chrono running...and I think the answer was "yes" but I cant remember why. I assume the watch would just stop slightly sooner because slightly more energy would be required to drive the complication...is that right?

Cheers

Paul


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## jasonm (Nov 22, 2003)

> I seem to remember another thread ages ago asking whether a manaul chrono watch would run down fast with the chrono running...and I think the answer was "yes" but I cant remember why. I assume the watch would just stop slightly sooner because slightly more energy would be required to drive the complication...is that right?


That is how it seems to me Paul, the energy that is stored in the spring must be used up sooner when all the chrono bits are whizzing around...my friend Dave who bought the SS18 Poljot chrono from JoT recently called to say its running down quickly...turns out hes got the chrono running all the time, explained the above and he called to say its still running down quickly







I asked him to show me how hes winding it.....he took it off and gave it about 4 turns







Ah...I said ( his first ever mechanical bless him ) Hes happy now









Jason M


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## raketakat (Sep 24, 2003)

I remember how delicately I wound my first mechanical







.


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## JoT (Aug 12, 2003)

jasonm said:


> That is how it seems to me Paul, the energy that is stored in the spring must be used up sooner when all the chrono bits are whizzing around...my friend Dave who bought the SS18 Poljot chrono from JoT recently called to say its running down quickly...turns out hes got the chrono running all the time, explained the above and he called to say its still running down quickly
> 
> 
> 
> ...


 Jason that's a relief ..














I used to get the best part of two days out of it when fully wound ... incidently Poljot quote the power reserve as 43 hours without chrono running and 37 hours with the chrono running.


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## Silver Hawk (Dec 2, 2003)

JoT said:


> incidently Poljot quote the power reserve as 43 hours without chrono running and 37 hours with the chrono running.


 Still trying to get my head around this...

does this mean that once the Poljot with chrono running has stopped (i.e. after 37hrs), if you then stopped the chrono, it would run for a further 6 hours?

Paul


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## raketakat (Sep 24, 2003)

No - the mainspring power would be exhausted.


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## raketakat (Sep 24, 2003)

Extra power is used when running the complication so the watch doesn't run as long after a full wind







.


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## Silver Hawk (Dec 2, 2003)

Ian,

I don't understand that...can you please explain?

The way I see it is that the same number of escapements must take place whether the chrono is running or not....correct?

Therefore the reason the watch stops 6hrs earlier with chrono running is soley due to extra inertia associated with the chrono....






















where have I gone wrong?























Paul


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## raketakat (Sep 24, 2003)

Thats how I see it. Extra energy is expended running the chrono. complication.

All that extra friction takes it's toll.

Mind you - you could ask an expert


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## raketakat (Sep 24, 2003)

I do see what you're getting at Paul but the energy expended PER escapement is higher the more machinery there is to power.

You don't get something for nothing







.


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## 036 (Feb 27, 2003)

Interesting stuff....

My interpretation was that having to drive the chrono gear trains etc requires more *torque* from the mainspring... hence as eventually happens the torque reduces below a certain critical level, then the watch stops.

Howver, surely then if your were to reduce the torque required to drive the movement, ie by stopping the chrono, the watch should run on for a bit?

Simon


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## Silver Hawk (Dec 2, 2003)

Si said:


> Interesting stuff....
> 
> My interpretation was that having to drive the chrono gear trains etc requires more *torque* from the mainspring... hence as eventually happens the torque reduces below a certain critical level, then the watch stops.
> 
> ...


Simon,

I think you're right and that's the point I was trying to make...

...on the Poljot with chrono running , torque / resistance (whatever you want to call it







) becomes too much at 37 hrs, so watch stops...

...turn off chrono and what's left in the main spring is enough to keep the watch going for a further 6 hrs...

Cheers









Paul


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## 036 (Feb 27, 2003)

All very well in theory, but I am not sure if that happens in practice - it may be that the watch does not stop as such but runs incorrectly - faster, I believe, as the spring becomes run down... maybe the remaining energy is dissipated in some way.


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