French Pendulum type

klokwiz

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Feb 4, 2009
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Hi, ran across this french clock pendulum. it appears to me that it is designed for some sort of temperature compensation with outer rods pressing down on the levers attached to the circle. it appears to me not to be adjusted properly as the levers will not be pushed on at this time. seems that ti has to be adjusted once the correct pendulum length is determined. Can anyone with experience on this one help?

P.S. there also appears to be a cover or something missing from it that would hide the internals


thanks, Joe

pic1.jpg pic2.jpg pic3.jpg pic4.jpg pic5.jpg
 

klokwiz

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After reading the attached info, I did not see any info on initial set up of the pendulum. any idea how that is done and under what conditions?

Joe
 

JimmyOz

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Feb 21, 2008
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Set the pendulum so it is keeping time.
Then loosen the two brass knobs that should let you drop the rods down till they push the steel levers up till they touch the round brass stops.
When the brass rods increase in length due to heat they will push down on the levers which will push up on the pendulum stops raising the pendulum, therefore it compensates.
 

Mike Mall

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Oct 27, 2021
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Set the pendulum so it is keeping time.
Then loosen the two brass knobs that should let you drop the rods down till they push the steel levers up till they touch the round brass stops.
When the brass rods increase in length due to heat they will push down on the levers which will push up on the pendulum stops raising the pendulum, therefore it compensates.
The rods, and levers are open and visible.

Just wondering, is the difference between cool, and warm noticeable?
 

klokwiz

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Jimmy, Thanks for that. any idea if this needs to be done at any specific temperature? I assume if it is done in hot weather then the rods will just relax and not lower bob. Given the low variance in temp in most modern homes it is likely a mute point.
Joe
 

JimmyOz

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I don't think it matters when you set it (altho maybe cooler months would be my chose). if you have the clock running on time the adjusting screw is set, the only thing that moves is the bob, up when temp heats them and back down to the set screw when it is cooler.
 

klokwiz

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Hi, It seems to me there has to be operational and setup guidelines for this type of temperature adjusted pendulum. Will need more research.

Just for the halibut i decided to run a little test to see if the thing actually works. I chilled it in my freezer, then set the device so it rested on the bob lower adjuster. I then set it out at room temp to see if the change in temp caused the rods to lift the bob off the lower adjuster. With a temp difference of 30 plus degrees I figured there had to be some change. Once it warmed up the expanded rods caused the bob to bottom on the rod levers and not the lower bob adjuster as it was set when cold. the photo shows the change, it is not quite 1 mm but is discernable.

It seems to me that device has to be set so the bob is suspended by the rods and levers and not the lower adjust nut, to allow it to have an effect when the temperature changes both ways. It only needs to be raised slightly over the lower adjuster to allow change in both directions. My theory is it should be set after getting a regulation of time keeping, you then set bob on the rods and lower the bottom adjuster to allow the bob to drop when rods cool. Joe

32 degrees.jpg room temp.jpg
 
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Mike Mall

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Oct 27, 2021
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Hi, It seems to me there has to be operational and setup guidelines for this type of temperature adjusted pendulum. Will need more research.

Just for the halibut i decided to run a little test to see if the thing actually works. I chilled it in my freezer, then set the device so it rested on the bob lower adjuster. I then set it out at room temp to see if the change in temp caused the rods to lift the bob off the lower adjuster. With a temp difference of 30 plus degrees I figured there had to be some change. Once it warmed up the expanded rods caused the bob to bottom on the rod levers and not the lower bob adjuster as it was set when cold. the photo shows the change, it is not quite 1 mm but is discernable.

It seems to me that device has to be set so the bob is suspended by the rods and levers and not the lower adjust nut, to allow it to have an effect when the temperature changes both ways. It only needs to be raised slightly over the lower adjuster to allow change in both directions. My theory is it should be set after getting a regulation of time keeping, you then set bob on the rods and lower the bottom adjuster to allow the bob to drop when rods cool. Joe

View attachment 730958 View attachment 730959
Thanks for the effort. I was wondering about this very thing.
Very cool,
to warm :)
 

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