Quarter Hour Chime Question

[RonR]

I am working on the movement shown in the photos below. The movement is from a Tambour style case. I think it is from England, but not certain. No names on the dial of the movement. The movement has removeable mainspring via small removeable plates on the back side (shown in photo) and removeable round disks that are under the click ratchet gears. It is a 3 gear train movement with Westminster chime on the quarter hour. As can be seen in one of the photos the quarter hour chime is controlled by the circular stop plate on the front of the movement into which drops a pin after either 4, 8, 12 or 16 notes have been hit. Between the plates and on the same arbor as the above mentioned circular stop plate is another circular stop plate and it has only one notch in it. It is aligned such that a pin will drop into the notch at the same time the pin on the front drops in just after the completion of the firt quarter hour. The notch on the inside stop plate has a sharpe starting drop and then a gradual sloping rise out. The lever that is rising out of the notch carries a on an extension of itself a stopping pallet that stops a pin on one of the wheels on the train, thus stopping the gear train during the execution of the second quarter hour chime sequence. I know something is wrong, but what??

 

[Scottie-TX]

What are the symptoms? What function is your clock not performing properly?

 

[Jerry Kenney]

Ron,

Sounds like maybe its the self correcting cam.

Jerry

 

[Sooth]

I'd be very curious to know the maker of this movement. It looks like a very good quality one. It's either German or English, but I'm leaning towards the first.

Any photo of the case?

 

[harold bain]

It does sound like the selfcorrecting cam. It should lock up after the third quarter chime finishes, and only be unlocked by the high lobe on the star cam.
Also the chime cam "appears" to be on backwards, depending on whether it rotates CW or CCW.

 

[lofty]

Ron, I agree with Harold. If the chime locking cam rotates clockwise, then I think it is on the wrong way.

Lofty

 

[Doug Henry]

The circular stop plate is correct for clockwise rotation. The lobes allow the chime movement to run, short period for the 1/4 hour, longer for 1/2 hour etc.

The second stop plate, as stated above, is a self correcting cam. It sounds like this plate is not orientated correctly to the 1/4 hour plate.

The slot in the second stop plate's pin will be in the slot when the 1/4 hour stop plate's pin is in it's slot prior to the longest cam lobe (the hour position).

The same function as Hermel and Urgos movements I have.

 

[Mike Phelan]

Ron
It is German, and looks like a Haller movement.
There are only a dozen or so English Napoleon movements, and it is none of these.

The cam you are referring to is indeed the self correct, but it should allow the lever to drop just before the third quarter, not the first.
This makes the detent drop on to, but not into, the locking cam on the wheel above. The longer point on the cannon pinion star cam for the hour raises the detent and unlocks the chime at warning.

All
The count wheel ("stop plate") is on correctly!
As the barrel winds CW (look at the ratchet) then the countwheel arbor also must be CW.
Therefore, the countwheel is on correctly because it has locked after the hour and before the first quarter as we can see from the picture. Simple, n'est-ce pas?

I'd hate to think of the fun and posts you would have if you reversed it!

 

[RonR]

Photo of the case is below. The case is 14 inches wides and 9 inches tall. The door on back lifts off easily via right angle bent metal hinges.

The stop plate(count wheel) rotate clockwise when seen from the front of the movement.

So based on your comments I need to remove the front stop plate(count wheel) and reinstall it such that front pin is in the slot just before the hour count at the same time the pin is in the self correcting slot. Does not this also mean that I will have to correct the positioning of the 4 point star on the minute hand arbor so that the one long point corresponds with the position of the now relocated position of the count wheel(front stop plate)??

 

[Mike Phelan]

[colour=red]No, stop![/colour]

Ron
If you move the count wheel then a few other things will need timing.
Assume this is OK at first - the SC (self-correct) cam is what needs to move.

There is no need to correlate the position of the star on the centre arbor; that is what the self-correct should do when it is running.
When the clock chimes 3/4, irrespective of where the hands are, the SC locks it doubly using the SC cam notch, and it does not then unlock until the long point of the star arrives just before the hour.

Worst case, if it chimes 3/4 it will not chime again until the hour, at which time it is then in sync,
So, it can take 3/4 of an hour to correct itself, not an hour or two hours or anything else - this has been written wrongly in books and then slavishly copied!

 

[LaBounty]

Hey Mike-

A few years ago I had a customer who wanted to know the maximum amount of time it can take for a clock to self correct. I was about to offer the standard 2 hour reply but this customer wanted an exact number. Here's what I puzzled out...

Picture advancing the minute hand to 15 minutes after without letting the hour complete its sequence until it is released at the 1st quarter. Then the first quarter chimes go off at the half, the half at the 3/4, the 3/4 chimes at the hour (at which point the self-correct kicks in), then nothing at a quarter after, nothing at half-past, nothing at a quarter 'till, then everything happens correctly at the hour. That would mean the clock ran for 1 hour and 44 minutes to correct itself. If it had run for 2 hours and still wasn't correct, there would be a problem.

This scenerio can actually be stretched if you consider that the hour sequence can be stopped when the chimes go into warning just before the quarter hour. So, it could actually take up to 1 hour, 55 minutes depending on when the sequence is considered to be "off".

Hope that helps!

 

[RonR]

Thanks for the technical help.
Anyone have a definitive ID on the clock origin, maker and age??

 

[shutterbug]

All
The count wheel ("stop plate") is on correctly!
As the barrel winds CW (look at the ratchet) then the countwheel arbor also must be CW.
Therefore, the countwheel is on correctly because it has locked after the hour and before the first quarter as we can see from the picture. Simple, n'est-ce pas?

Mike, I'm with you up to a point It looks like the wheel needs to be turned around so the tapered part of the grove can lift the pin as the clock rotates. As is, it looks like they will lock (and operate in reverse order).

 

[RonR]

shutterbug, mike is correct, the count is mounted correctly. Look at the length of the rim between the slots. The wheel rotates in a clockwise direction. So the short segment allows 4 strikes, the next segment allows 8 strikes and so on. The pin does not rise out of the slot as the count wheel rotates, it is raised out "so" the count wheel will be allowed to rotate.

 

[harold bain]

Ron, hard to put a date to your clock. The case style was used from about the 1920's to 1950's. I think Mike is correct about German origins.

 

[shutterbug]

shutterbug, mike is correct, the count is mounted correctly. Look at the length of the rim between the slots. The wheel rotates in a clockwise direction. So the short segment allows 4 strikes, the next segment allows 8 strikes and so on. The pin does not rise out of the slot as the count wheel rotates, it is raised out "so" the count wheel will be allowed to rotate.

OK Ron, I can see what you mean. I thought it would rotate the opposite way for some reason, but why I thought that is beyond me now

 

[Mike Phelan]

Hey Mike-

A few years ago I had a customer who wanted to know the maximum amount of time it can take for a clock to self correct. I was about to offer the standard 2 hour reply but this customer wanted an exact number. Here's what I puzzled out...
[snip] That would mean the clock ran for 1 hour and 44 minutes to correct itself. If it had run for 2 hours and still wasn't correct, there would be a problem.
Hope that helps!

You are right, David - I was looking at it from the point of view of how long it was when it did not chime at all rather than including it chiming incorrectly . Good job I don't do customers!
The textbooks I have seen are a bit ambiguous on this point as a lot of them seem to gloss over anything about chiming or striking.
Off topic:
Some of the self-corrects are over-elaborate (Enfield) and others very simple and neat (Perivale). I'll do a write-up on them sometime ....

 

[Mike Phelan]

Mike, I'm with you up to a point It looks like the wheel needs to be turned around so the tapered part of the grove can lift the pin as the clock rotates. As is, it looks like they will lock (and operate in reverse order).

SB
I was fooled by one of these years ago! It works because the actual stop on the wheel above is a cam, not the more general pin. It would just jam in the "grove" [sic] in that case.
A bit like what you call the maintenance cam on an OG having to miss the teeth on the countwheel by raising the detent.