The mysterious Speedmaster hour counter

[Archer]

I do typically take a photo of the back of each dial, as part of the series of photos I take for each watch I service.

I have not compiled them in any way...but they do vary in appearance over time certainly.

 

[pascs]

Archer

I then check to make sure that the hour counter doesn’t creep with the chronograph stopped, and also that the hour counter does advance when the chronograph is running. Additional checks are done once the watch is fully assembled, but this catches any gross problem before I have mounted the dial and hands.

More to come in another post...

Thanks for the great detail and explanations 👍

One of mine has an odd behavior of the hour reset, the hour hand will creep only occasionally. After I rebuilt the movement, I tested it for a few days without the dial and it was running fine with the hour hand fitted, but when I put the dial and cased the movement it creeps occasionally. I think its because the pusher stem for zero action is sticking slightly and causes the hour hammer to interfere with the hour counter lock lever and prevents it from sitting correctly on the hour wheel. I'll be stripping it down again soon but hopefully this detailed explanation will help me to identify the issue.

 

[Archer]

So just a word about other chronographs - someone asked about the Cal. 321, and the design on that is very similar:



The parts look a little different, but the mechanism works in the same way. Here is the dial side of an ETA 7750:



It works in the same way, but the drive pinion that is on the mainspring barrel is fixed, and the slipping "clutch" that allows the reset and for the hour recorder to stay put when the barrel is turning and the chronograph is running, are built into the hour counting wheel. Here is that wheel:



And you can see the spring here that contacts the wheel in 3 spots, and this is where oil is applied to make sure that this part slips as it should in use:



So in a recent thread someone mentioned that the hour counting hand would be centered when the reset pusher was pressed, but would move slightly off center when the button was released. There are two common reasons for this:

1 - Magnetism - if the hammer or cam is magnetized, when the hammer comes down to reset and then lifts off as you let go of the pusher, it can cause the cam to stick to the hammer, and it can cause slight movement of the hour counting wheel. The solution to this is demagnetizing the movement.

2 - Excess or sticky oil - if the hammer or cam are oiled too much, or the oil is very sticky, it can cause the same thing to happen as in the case of magnetism. The solution there is service.

There is another one I didn't mention in that thread, because it's not common on newer watches...

3 - Damage to the hole in the main plate of hour recorder bridge - the hour counting wheel has a pivot that fits in a hole that is made in the main plate of the watch, and the other end sits in a bushing that is in the hour recorder bridge.

When these holes are worn or damaged and are oversized, the hour hammer will push the hour counting wheel to one side of the hole on reset, but the wheel will move when that pressure from the hammer is released.

Here is a photo of a bushing that was damaged:



This is easily repaired by replacing the bushing in this bridge. The same problem can happen on the main plate, as shown here:



This is a more difficult problem to fix, so my advice to people is if you find that the reset of your watch is getting to be difficult, requiring more effort, please don't force it - get the watch in to be serviced.

For the most part the hour counting mechanism works well, but again since the entire thing is based on a friction clutch, note that a sharp shock to the watch could cause the counter to move.

Anyway, I hope this helps you all understand this part of the watch more completely. If you have any questions regarding this, please ask and I'll do my best to answer.

Cheers, Al

 

[reverbtime]

Thank you for this informative post!

 

[noelekal]

We're grateful that you're here on the Forum. In this thread I learned that Speedmaster hour hands can creep when the chronograph is not activated as well as learning why.

It's plain to see that Archer is passionate about his craft.

 

[chaw6125]

Archer

Here is a photo of a bushing that was damaged:

Al - thanks for the insight. This is a great post.

With a worn bushing like that would you replace it with another or would you instead install a jewel?

 

[Blackdog]

Excellent post ! Always wondered how the hour counter actually worked. Not being visible indeed made it mysterious to me !

Many thanks for a very didactic post !

 

[Archer]

chaw6125

Al - thanks for the insight. This is a great post.

With a worn bushing like that would you replace it with another or would you instead install a jewel?

No, just a bushing. Keep in mind this rotates very slowly...once every 12 hours. The damage is more from someone pressing too hard than it is actual wear.

 

[W210]

Archer

I've been meaning to put together some information about one of the features of Speedsters that seems to generate the most questions - the hour counter. I’ve posted details of this in various places over the years, but since questions about this function keep coming up, I wanted to consolidate it all in one thread.

There are often questions about how it’s not centered, why it isn’t accurate, why it creeps when the chronograph isn’t running, so I wanted to show some details of how this counter works, so you can all understand why it might do some of the things it does.

So the first thing to show is how the chronograph functions are operated on a Speedmaster, and for illustration purposes I will show photos from a Cal. 861 below.

Here is the back side of a Cal. 861 Speedmaster:



This first video will show the start, stop and reset sequence:

There are really two key points here:

1 – The seconds counting hand and the minute counting hand are driven by a wheel that is on an extended post from the fourth wheel of the movement. That wheel in turn drives a wheel on the coupling yoke, and the cam moves that yoke in and out to make contact with the chronograph wheel, to start the chronograph running.

2 – In the reset state, the hammer that resets both the seconds and minute counting hands is at rest against the cams of those wheels. You can see the hammer swing up and away from the cams when the chronograph has been started, and on the reset the hammer quickly swings down to reset those two wheels. The hammer movement on the reset comes from a long spring, so the hammer speed is determined by that spring.

So the one thing I don’t mention here is the hour counter, and that’s because it has no real direct connection to any of the parts I just mentioned. That’s because the hour counter is driven off the mainspring barrel, not from the wheel that is on the fourth wheel post, so it is driven independently of the seconds and minutes counting wheels.

Here is the dial side of a Cal. 861, and this is only partially assembled:



And here it is with the remainder of the parts in place:



The various parts have letters on them, so here is a list with descriptions:

A – mainspring barrel
B – friction spring for driving pinion
C – driving pinion
D – hour counting wheel
E – hour hammer
F – hour counter lock

The mainspring barrel A turns all the time that the watch is running, and so does the friction spring B that is screwed into that barrel cover. That spring will make the driving pinion C turn, if it is able to, and if that pinion is blocked, it will slip against the mainspring barrel.

The driving pinion C will turn the hour counting wheel D, but only if not blocked by the hour counter lock F. The hour hammer E is what resets the hour counting wheel D.

So when the chronograph is switched off, and the watch is reset, the parts are in the positions you see them in this photo I used above:



The hour counter lock F is sitting firmly against the hour counting wheel D, which means that the wheel is not turning, the driving pinion C is not turning. You will note that the hour hammer E is retracted out of the way, so that the hammer is not resting on the cam of the hour counting wheel. If you recall the seconds and minute counters, when reset the wheels are held in place by the hammer, but that is not the case for the hour counter so this is a major difference.

So when the chronograph has been started, the hour counter lock F is moved, which allows the hour counting wheel D to be driven by the driving pinion C, and the hour counter starts to move. It moves continuously, so there is no jumping feature on these watches for the hour counter. When the chronograph is stopped, the hour counter lock F comes back in contact with the hour counting wheel D, and it holds that wheel in place so that the user can look at the hand to determine the elapsed time.

On reset, the hour hammer E swings down and contacts the hour counter lock F, and pushes it out of the way. The hammer then carries on and strikes the cam on the hour counting wheel D, and resets the wheel to it’s home position. Now remember that the driving pinion C is only connected to the mainspring barrel A, by the friction spring B. This allows the hour counting wheel teeth to stay engaged with the driving pinion, and the driving pinion spins under the friction spring as it’s being reset.

You can see the reset portion of this sequence here – note the hole that is in the hour counting wheel moves when the hammer comes down onto the cam:

Now one thing to note is that the reset sequence as you would use the watch looks to be all one thing, but in reality it's in two parts. Remember the hammer for the seconds and minute counters is spring loaded to reset, so when you push the reset pusher, this will move a part called the stem bolt for hammer out of the way of the hammer, and the spring snaps the hammer down on the cams.

Back to this photo again now:



If you look at the letter E on the hour hammer, there is a part with a hole in it directly to the right of the hammer - this is the hour hammer operating lever, and it is moved by the pusher stem for zero action. These two parts are moved by the pusher that you press.

So as the reset pusher continues to move in towards the case, and after the hammer for the seconds and minute counters has reset, the pusher stem for zero action presses on the hour hammer operating lever, and this moves the hammer down to reset the hour counting wheel. These are two distinct operations, and I showed this is a video I took some time ago:

You can see here that I was able to reset the seconds and minutes, without resetting the hour counter. I sometimes get questions about why the hour counter reset is sluggish, and the speed that it resets is directly related to how quickly you press the pusher in.

So this is an overview of the basic operation, and in subsequent posts I'll go over some of the common problems seen with this function.

Cheers, Al

Wonderful post, thanks Archer !!!

 

[newairplane]

Archer - very nice work!

I just purchased a circa 1969 Speedmaster mark II with racing dial. My local jeweler installed a new crystal, lubricated some parts and adjusted it so it keeps excellent time. The watch looks great. The reset for the chrono does not work right though, the "hour hammer operating lever" seems to get stuck in the depressed state, even though its pusher is fine. The little spring loaded pin that is actuated by the hammer moves freely and the spring seems ok. It seems to be a sticky "hour hammer operating lever". I have carefully removed the back cover to take a look. Problem 2: The hour dial at 6:00 position moves along with the hour hand even if the chrono is stopped. It never resets. Do you have any suggestions for how I might go about having this repaired? I am not good enough to tear down the mechanism and would not attempt it.

Thanks

Rick

Archer

I've been meaning to put together some information about one of the features of Speedsters that seems to generate the most questions - the hour counter. I’ve posted details of this in various places over the years, but since questions about this function keep coming up, I wanted to consolidate it all in one thread.

There are often questions about how it’s not centered, why it isn’t accurate, why it creeps when the chronograph isn’t running, so I wanted to show some details of how this counter works, so you can all understand why it might do some of the things it does.

So the first thing to show is how the chronograph functions are operated on a Speedmaster, and for illustration purposes I will show photos from a Cal. 861 below.

Here is the back side of a Cal. 861 Speedmaster:



This first video will show the start, stop and reset sequence:

There are really two key points here:

1 – The seconds counting hand and the minute counting hand are driven by a wheel that is on an extended post from the fourth wheel of the movement. That wheel in turn drives a wheel on the coupling yoke, and the cam moves that yoke in and out to make contact with the chronograph wheel, to start the chronograph running.

2 – In the reset state, the hammer that resets both the seconds and minute counting hands is at rest against the cams of those wheels. You can see the hammer swing up and away from the cams when the chronograph has been started, and on the reset the hammer quickly swings down to reset those two wheels. The hammer movement on the reset comes from a long spring, so the hammer speed is determined by that spring.

So the one thing I don’t mention here is the hour counter, and that’s because it has no real direct connection to any of the parts I just mentioned. That’s because the hour counter is driven off the mainspring barrel, not from the wheel that is on the fourth wheel post, so it is driven independently of the seconds and minutes counting wheels.

Here is the dial side of a Cal. 861, and this is only partially assembled:



And here it is with the remainder of the parts in place:



The various parts have letters on them, so here is a list with descriptions:

A – mainspring barrel
B – friction spring for driving pinion
C – driving pinion
D – hour counting wheel
E – hour hammer
F – hour counter lock

The mainspring barrel A turns all the time that the watch is running, and so does the friction spring B that is screwed into that barrel cover. That spring will make the driving pinion C turn, if it is able to, and if that pinion is blocked, it will slip against the mainspring barrel.

The driving pinion C will turn the hour counting wheel D, but only if not blocked by the hour counter lock F. The hour hammer E is what resets the hour counting wheel D.

So when the chronograph is switched off, and the watch is reset, the parts are in the positions you see them in this photo I used above:



The hour counter lock F is sitting firmly against the hour counting wheel D, which means that the wheel is not turning, the driving pinion C is not turning. You will note that the hour hammer E is retracted out of the way, so that the hammer is not resting on the cam of the hour counting wheel. If you recall the seconds and minute counters, when reset the wheels are held in place by the hammer, but that is not the case for the hour counter so this is a major difference.

So when the chronograph has been started, the hour counter lock F is moved, which allows the hour counting wheel D to be driven by the driving pinion C, and the hour counter starts to move. It moves continuously, so there is no jumping feature on these watches for the hour counter. When the chronograph is stopped, the hour counter lock F comes back in contact with the hour counting wheel D, and it holds that wheel in place so that the user can look at the hand to determine the elapsed time.

On reset, the hour hammer E swings down and contacts the hour counter lock F, and pushes it out of the way. The hammer then carries on and strikes the cam on the hour counting wheel D, and resets the wheel to it’s home position. Now remember that the driving pinion C is only connected to the mainspring barrel A, by the friction spring B. This allows the hour counting wheel teeth to stay engaged with the driving pinion, and the driving pinion spins under the friction spring as it’s being reset.

You can see the reset portion of this sequence here – note the hole that is in the hour counting wheel moves when the hammer comes down onto the cam:

Now one thing to note is that the reset sequence as you would use the watch looks to be all one thing, but in reality it's in two parts. Remember the hammer for the seconds and minute counters is spring loaded to reset, so when you push the reset pusher, this will move a part called the stem bolt for hammer out of the way of the hammer, and the spring snaps the hammer down on the cams.

Back to this photo again now:



If you look at the letter E on the hour hammer, there is a part with a hole in it directly to the right of the hammer - this is the hour hammer operating lever, and it is moved by the pusher stem for zero action. These two parts are moved by the pusher that you press.

So as the reset pusher continues to move in towards the case, and after the hammer for the seconds and minute counters has reset, the pusher stem for zero action presses on the hour hammer operating lever, and this moves the hammer down to reset the hour counting wheel. These are two distinct operations, and I showed this is a video I took some time ago:

You can see here that I was able to reset the seconds and minutes, without resetting the hour counter. I sometimes get questions about why the hour counter reset is sluggish, and the speed that it resets is directly related to how quickly you press the pusher in.

So this is an overview of the basic operation, and in subsequent posts I'll go over some of the common problems seen with this function.

Cheers, Al

 

[Archer]

newairplane

Archer - very nice work!

I just purchased a circa 1969 Speedmaster mark II with racing dial. My local jeweler installed a new crystal, lubricated some parts and adjusted it so it keeps excellent time. The watch looks great. The reset for the chrono does not work right though, the "hour hammer operating lever" seems to get stuck in the depressed state, even though its pusher is fine. The little spring loaded pin that is actuated by the hammer moves freely and the spring seems ok. It seems to be a sticky "hour hammer operating lever". I have carefully removed the back cover to take a look. Problem 2: The hour dial at 6:00 position moves along with the hour hand even if the chrono is stopped. It never resets. Do you have any suggestions for how I might go about having this repaired? I am not good enough to tear down the mechanism and would not attempt it.

Thanks

Rick

Hi Rick,

It really sounds like you need to find a proper watchmaker to look at this. You won't see much from the back, as the hour recorder parts are under the dial as I've illustrated.

The hour hammer operating lever is pushed back out by the hammer itself. The hammer is moved by the hour hammer spring - I recently had another watchmaker email me as he was having trouble with the hour recorder mechanism, and a similar issue to what you describe. The hour hammer wasn't returning back out to the home position, and eventually I figured out that he hadn't hooked the hour hammer spring into the hour hammer properly. So for this specific issue, that's where I would start.

However the description you gave about what was done - lubricating a few points and then regulating - that's not a full service, so unless you have a known service history for this watch, you should get it fully serviced. This involves complete disassembly, cleaning, replacing/repairing parts as needed, fresh lubrication in all areas. As I've noted above, your second issue (hour recorder creep) is usually solved by just a proper service.

Cheers, Al

 

[pdxleaf]

Archer

Okay, part 2...
So another common complaint regarding the hour counter is that it doesn’t stay in sync with the minute counter. The most common reason for that is that the hour counter hand isn’t 100% aligned properly when it’s installed, so in most cases just installing the hand correctly is enough to make things line up fine...

This is my issue, (no creep).

My watch is new (now a year old 1861). Since new, the hour counter shows more time passed than the minutes. For example, for the first 30 mins, the hour counter is past the half way mark. For the second half hour, the hour counter is near to the first hour mark. Once the hour has elapsed, the one hour mark is (generally) aligned with the one hour indicator.

The problem is that it makes it a bit tricky to discern whether the i am coming up on the first 30 mins or whether i am on 31 plus mins.

I had accepted this as normal for 1861s.

Here is the question: are you saying this is not normal and (in the case of a new watch) a result of inaccurate alignment at the factory? If so, then is this something covered by the warranty and also something an owner should expect to be corrected by returning it to Omega?

If yes (it should be corrected), is it worth the risk that incurs whenever a watch is opened and taken apart? It is functional as i have learned its quirk. It's a bit annoying but is the adjustment for this one small tick worth the effort of taking apart a new watch?

Sorry for the delayed post. I wanted to read this for awhile but wanted the time to sit and absorb it, which is this Saturday morning.

Thanks Al. Hope you guys are staying warm.

Dave

 

[Archer]

pdxleaf

For example, for the first 30 mins, the hour counter is past the half way mark. For the second half hour, the hour counter is near to the first hour mark. Once the hour has elapsed, the one hour mark is (generally) aligned with the one hour indicator.

So is this another way of saying that the counter is too far ahead the whole time?

I'm not sure I 100% understand the issue...

 

[rob#1]

Very informative, thanks @Archer . Took me a few goes to get my head around it but it makes sense now. I can only imagine what it would have been like designing and testing these mechanisms all those years ago...

 

[jaguar11]

Outstanding post and one which I have only just caught up with!

 

[Pazzo]

jaguar11

Outstanding post and one which I have only just caught up with!

+1
@Archer Thank you very much.

 

[Nyrmala]

Very informative post.

It seems like I've got a similar issue with the hour hand regarding my 3594.50 Broad Arrow.
1861 movement and while everything runs perfectly fine, I realized that when the chronograph is running for more than an hour, If I stop it and hit the reset pusher, everything goes back to 12 except the hour hand that doesn't fully reset.
It goes back but stops on the way and If I want to fully reset it, I need to hit the reset pusher a second time.

What could be the problem here ?
Other than the reset part, the hour hand runs fine while the chronograph is also running.

Should I send it to Omega for full service or would a local watchmaker be enough for this particular issue ?

Thanks @Archer

 

[Archer]

N Nyrmala

Very informative post.

It seems like I've got a similar issue with the hour hand regarding my 3594.50 Broad Arrow.
1861 movement and while everything runs perfectly fine, I realized that when the chronograph is running for more than an hour, If I stop it and hit the reset pusher, everything goes back to 12 except the hour hand that doesn't fully reset.
It goes back but stops on the way and If I want to fully reset it, I need to hit the reset pusher a second time.

What could be the problem here ?
Other than the reset part, the hour hand runs fine while the chronograph is also running.

Should I send it to Omega for full service or would a local watchmaker be enough for this particular issue ?

Thanks @Archer

If it has been more than say 7 years since it was serviced, it likely needs a full service.

You could use Omega or an independent that is certified by Omega, and has access to all parts that might be needed.

 

[pdxleaf]

Archer

...So the one thing I don’t mention here is the hour counter, and that’s because it has no real direct connection to any of the parts I just mentioned. That’s because the hour counter is driven off the mainspring barrel, not from the wheel that is on the fourth wheel post, so it is driven independently of the seconds and minutes counting wheels....

Archer

The various parts have letters on them, so here is a list with descriptions:

A – mainspring barrel
B – friction spring for driving pinion
C – driving pinion
D – hour counting wheel
E – hour hammer
F – hour counter lock

Are you familiar with the Excelsior Park 40, and if so, does the hour counter operate similarly to Omega's 861?

I have some creep and am speculating on whether it is fixable or if I should live with it.

The watch was serviced about a year ago. While it's possible it wasn’t lubricated properly, at this point I'd like to assume the creep is not due to lubrication. (It could still be the barrel as you mentioned, but for now I am focusing on the possibility of the counting wheel.)

My main question is if the creep is due to a worn hour counting wheel or hour counter lock (such as are in the Speedy), is the only solution to replace the wheel or lock? I assume these are still available from Omega so not a problem if they are worn. I am concerned that similar parts for an EP 40 are not available, which either means scavenging another movement (expensive and difficult to find) or fabrication of a new wheel for example?

This question may be out of scope for this thread, in which case I apologize. I don't pretend to be a watchmaker. I'm mainly trying to figure out how much cash I'll need to throw at this.

Thanks for any insights you can share.

 

[Archer]

pdxleaf

Are you familiar with the Excelsior Park 40, and if so, does the hour counter operate similarly to Omega's 861?

I have some creep and am speculating on whether it is fixable or if I should live with it.

The watch was serviced about a year ago. While it's possible it wasn’t lubricated properly, at this point I'd like to assume the creep is not due to lubrication. (It could still be the barrel as you mentioned, but for now I am focusing on the possibility of the counting wheel.)

My main question is if the creep is due to a worn hour counting wheel or hour counter lock (such as are in the Speedy), is the only solution to replace the wheel or lock? I assume these are still available from Omega so not a problem if they are worn. I am concerned that similar parts for an EP 40 are not available, which either means scavenging another movement (expensive and difficult to find) or fabrication of a new wheel for example?

This question may be out of scope for this thread, in which case I apologize. I don't pretend to be a watchmaker. I'm mainly trying to figure out how much cash I'll need to throw at this.

Thanks for any insights you can share.

I can't say anyone has ever asked me to service one, so I don't have any direct experience. However if you look at this thread there are photos of one being taken apart:

https://forumamontres.forumactif.com/t26579-chronographe-excelsior-park-40-huileux

Here is a dial side photo from that thread that I cleaned up the lighting on, and you can see that instead of the hour counter being run directly off the barrel, it's being run from the hour wheel. So there must be a mechanism that turns this on and off, but just looking at the photos it's unclear to me exactly how that is accomplished.