Strike train warning system - why?

[LarryAC]

This is probably a silly question and I'm still very much a noob at restoring old clocks but I've worked on a half dozen now and have somewhat figured out how the warning systems work and how to adjust them, but I cannot figure out WHY clocks have have a warning system. I read Conover's Striking Clock Repair Guide but he only describes how to adjust them, not why they are necessary. Can someone explain this to me?

 

[wow]

This is probably a silly question and I'm still very much a noob at restoring old clocks but I've worked on a half dozen now and have somewhat figured out how the warning systems work and how to adjust them, but I cannot figure out WHY clocks have have a warning system. I read Conover's Striking Clock Repair Guide but he only describes how to adjust them, not why they are necessary. Can someone explain this to me?

This is probably a silly question and I'm still very much a noob at restoring old clocks but I've worked on a half dozen now and have somewhat figured out how the warning systems work and how to adjust them, but I cannot figure out WHY clocks have have a warning system. I read Conover's Striking Clock Repair Guide but he only describes how to adjust them, not why they are necessary. Can someone explain this to me?

Here’s a couple of explanations.

 

[John VCW]

Hi

The lock lever is a hefty arm aligned to lock a lower gear which rotates slowly and has high torque. Thus, the lever is activated by a cam that raised it slowly as it is under pressure from the stop pin. It would be hard to release this lever precisely as the clock wears with time. (Some clocks actually do this)

The warm lever is often on the last wheel, or on the fly (both high speed when under way). This is a great low torque position to release the train from, but a poor position to stop the train when under way.

Way back, someone figured out to use both, a heavy built stop lever on a lower gear for stopping and a lighter low load pin/lever on the warn to trip off and start the train. Usually the warn pin is set ~180 degrees from where the stop lever engages the stop pin. This allows for a precise trip of the train while providing for the stop lever to have moved out of the way.

The usual alignment is the hammer starwheel is in between lobes, stop pin engaged, warn pin 180 degrees out from the warn lever

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[wow]

Hi

The lock lever is a hefty arm aligned to lock a lower gear which rotates slowly and has high torque. Thus, the lever is activated by a cam that raised it slowly as it is under pressure from the stop pin. It would be hard to release this lever precisely as the clock wears with time. (Some clocks actually do this)

The warm lever is often on the last wheel, or on the fly (both high speed when under way). This is a great low torque position to release the train from, but a poor position to stop the train when under way.

Way back, someone figured out to use both, a heavy built stop lever on a lower gear for stopping and a lighter low load pin/lever on the warn to trip off and start the train. Usually the warn pin is set ~180 degrees from where the stop lever engages the stop pin. This allows for a precise trip of the train while providing for the stop lever to have moved out of the way.

The usual alignment is the hammer starwheel is in between lobes, stop pin engaged, warn pin 180 degrees out from the warn lever

[email protected]

Welcome, John. Good to have you on the message board. I see you are a new user. We need experienced people like you. Good looking website!
Will

 

[disciple_dan]

I just wanted to add that it also prevents the train from relocking when the levers drop to release the run. At warn the train advances enough so that when it drops for the strike the locking position has been moved and it continues on its way.
I hope that makes sense. Danny

 

[LarryAC]

Thanks for the responses. It's making some sense. From John's comment, though, is the warning system a relatively recent addition to the strike train and do much older clock movements not have this?

 

[wow]

Thanks for the responses. It's making some sense. From John's comment, though, is the warning system a relatively recent addition to the strike train and do much older clock movements not have this?

Even old wooden works clocks 200 years old have warning. Off the top of my head, I can only think of one style that does not have that same warn set-up. The French Morbiers are different.

 

[R. Croswell]

Larry, the real reason for the "warning system" is somewhat different. The strike train does not need the warning system to operate. You can easily demonstrate this by quickly lifting and dropping the count lever (or rack hook on a rack and snail clock) and the strike train will begin and count the hour and stop. All the strike train needs is a brief "signal" from the time train to know when to strike. Because the minute hand turns so slow there is plenty of power (torque) to unlock the strike train at any point in the train that the maker might select. Quite a few American clocks lock the strike train directly on the maintenance cam. So why the warning run?

The answer is quite simple but not easy to visualize. In digital speak, one might say that the pulse width of the start signal to initiate striking is wider than the duration of the event being initiated. In simpler turns, The minute hand turns so slowly that if there was no warning system, the striking would begin sometime on the approach to the top of the hour just before the "J" hook drops. That's OK, with care we could get the striking to begin pretty close to the top of the hour, but the strike count will be complete (especially the lower numbers) before the minute can advance to the "strike off" position ("J" hook drop). The strike train therefore is still getting the signal to begin striking and goes on to strike the next hour, and the next, until the minute hand advances far enough to drop the "J" hook and sand the "stop striking this hour" signal. Explained differently, the time train needs to send the signal to begin striking and then decouple itself and allow the strike train to stop on its own when the strike count is complete. The warning system provides this decoupling.

If you have an old count wheel movement that will strike, bent the warning lever out of the way and see how it acts. If you advance the minute hand rapidly past each hour it should work fine, although it will strike a few minutes early, but if you allow the clock to run on its own you will see that striking will begin but will run on and on and on for several minutes until the minute hand is past the "it's time to strike" position.

A secondary reason for the warning run is that it is much easier to sync the start of striking to the sudden drop off of the "J" hook than to some arbitrary point on the slop leading up to the drop off. So the warning run system is a neat little invention that kills two birds with one stone.

RC

 

[Mike Phelan]

Most Dutch clocks had no warning; neither did Morbiers nor old clocks using the "flirt".
The very first old iron clocks in monasteries didn't either.