How does a crutch pushing on the side of a pendulum work? Sattler Mechanica M1

DannyBoy2k

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One clock I've looked at and debated purchasing for years is the Sattler Mechanica M1 clock kit. One aspect of that movement that has puzzled me is how the crutch pushing on the beat adjuster on the left side of the pendulum could provide an impulse for both directions of swing. I've attached an image from their manual that shows the arrangement.

crutch_side_pendulum.png

With the pendulum swinging to the right, I can see how it provides an impulse. However, when swinging to the left, it seems like there is nothing to prevent the crutch from just jumping off the beat adjuster when the pallet receives its impulse. I feel like I'm clearly missing something, but not sure what.

The only really good video I've seen of this clock in operation is this one. Unfortunately, while he's peaking around under the movement, he doesn't quite show the action of the crutch pin.

So, what am I missing?

Cheers,
Dan
 

DannyBoy2k

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Thanks, Bruce. Before posting, I had already read that whole manual top to bottom and, while it has some fantastic information about adjusting the pallets for drop and lock and how a clock operates, it doesn't address this question. That manual is where I took the image from above.

The beat adjuster is pinned to the pendulum and can rotate about that pin point. The "pallet arbor crutch" as they call it pushes on the top of the beat adjuster, but is not attached to it, just resting against it.

~Dan

Another, similar image from the manual:
crutch_side_pendulum_2.png
 
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shutterbug

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There are only two possibilities in my mind. Either the crutch pin has a slot that the beat adjuster slips into, or the pendulum is powered only by the exit pallet - like a true half deadbeat. My instinct is that the pin connects to the adjuster in some way.
 

bruce linde

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all I can surmise is that the pendulum rod pushes everything to the left, and then maybe the weight of the crutch rod and the absence of push allow it to follow the pendulum to the right.

Why don’t you email them and ask? :)
 
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DannyBoy2k

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Well, just sent them a note on their Mechanica specific website (Uhrenbausatz | MECHANICA - Ihr persönliches Stück Zeitgeschichte). Hope to hear back from them.

I really don't think the crutch pin is restrained in any way. At least, not in any way that the manual demonstrates. Kind of thinking Shutterbug might be right about it being a half deadbeat, though the manual says "In our M1 we use the so-called 'dead beat' escapement invented by George Graham in 1720".

~Dan
 

shutterbug

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Yeah. In that PDF file it also mentioned that the impulse has to be constant forces, which is not what a half beat would provide. Interesting clock!
 

DannyBoy2k

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Much to my delight, I've already heard from from them. My question was similar to what I posted above: how can the escapement mechanism provide an impulse to both swings of the pendulum or does it only impulse it for half of its period?

It´s completely correct, the pendulum gets its impulse only from one side, while swinging to the right side. So it gets just one impulse per period.

While swinging to the left side, the pin stays on the beat adjustment but gives no impulse to the pendulum.
Well, there you go. Mystery solved. I am surprised no mention of this is given in the very detailed clock theory section at the end of the manual. It would actually be a fascinating discussion to explain this engineering decision. Knowing this now, I wish I had a detailed, up close shot of their pallets. I wonder if one pallet is completely missing the impulse face; after all, what good would that do? Also, it would explain how they keep the crutch pin from potentially jumping off the beat adjustment.

~Dan
 
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Darrmann39

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all I can surmise is that the pendulum rod pushes everything to the left, and then maybe the weight of the crutch rod and the absence of push allow it to follow the pendulum to the right.

Why don’t you email them and ask? :)
That was exactly my thought that it was weight. Being tilted off plumb it has no choice but to release it back the other way. The weight driving it back
 

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