Unusual Escapement

That's an excellent question!

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It’s worth watching this :

[ sorry]  … duplicate post

MichaelG.

Edited By Michael Gilligan on 21/06/2022 00:57:38

A good find Michael! I've read Philip Woodward's description of this but never seen one or a video. Here the conical pendulum is being driven just like the one on the Farcot clock but faster, and just needs to allow the cam that resets the gravity arm to rotate one rev in slightly less time than one pendulum cycle.

Nicely put, John

In my opinion … The Bond was a work of genius

MichaelG.

So if I've analysed this correctly (or at least some of it) after watching the Bond clock several times, it's a free pendulum clock with gravity escapement where the pendulum only unlocks the escapement. The conical pendulum at the top provides a constant velocity drive to reset the escapement, trigger the electrical contacts and drive the hands. In essence acting as a kind or remontoire. As has been said it's quite ingenious.

I'd be interested to read what others have spotted.

regards Martin

A conical flywheel makes a lot more sense. If you take a small amount of energy out, the speed drops, so the ball radius drops, which means that the drop in speed is less than it would have been if the radius was fixed. I could do some sums, but it's too hot.

That makes sense Duncan. Intuitively when the spherical pendulum does work the slowing of the angular velocity causes the bob to fall and the radius to reduce which transfers potential energy back into kinetic energy which moderates the loss of angular velocity which is what you said. I did look for the maths but as it hared off into Hamiltonians and Lagrangian mechanics I gave that up as a bad job.

regards Martin

The sums required an ice pack, for reasons I'll go into later. taking equations 1 & 2 from my original link and doing a bit of re-arranging you get cos(theta)=g/(w^2*L). Then taking a mass 1 kg on a rod 1m long rotating at such a speed as to make the rod be 30 degrees from vertical

so the conjecture is proven.

The problem comes when the angle gets lower, in fact if L*w^2<g you get cos(theta)>1 which is impossible. I think this reflects what happens if you have a ball rolling round in a curved dish, there comes a point when the ball stops rolling round in decreasing circles and heads for the middle, but if anyone can confirm my ramblings I'd be happier.

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What makes you think that the rod of the conical pendulum is 1m long

MichaelG.

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Edited By Michael Gilligan on 21/06/2022 20:23:59

nothing, I just picked some numbers to see what happens when it slows down. With the wonders of SMath you can just change the numbers at the beginning and it alters all the arithmetic

Edited By duncan webster on 21/06/2022 20:19:57

And in the video (thanks Michael) what about those missing gear teeth from about 4:10?

Ensuring synchronised re-engagement has to be yet another clever piece of the design.

Albeit set by hand, that was a problem I encountered during the design and construction of the mechanism for a popular TV game.

Sam

The missing teeth were, I believe, an improvement introduced after the original build

I do have some information about the modification, but cannot locate it at present.

MichaelG.

Thanks Michael, I look forward to reading anything you find.

Cheers,

Sam

Try this, Sam :**LINK**

https://books.google.co.uk/books?id=bd7pbFyPCuIC&pg=RA6-PA30&lpg=RA6-PA30&dq=hartnup+bond+escapement&source=bl&ots=eeymCh9dla&sig=ACfU3U1ypyCJ2BYoogJ1oCgiKOubcUQKRA&hl=en&sa=X&ved=2ahUKEwimo5mt17_4AhWMCcAKHcIKCN0Q6AF6BAgeEAM#v=onepage&q=hartnup%20bond%20escapement&f=false

MichaelG.