Classic Escapement - Recoil (Brocot)

Last crawled date: 1 year, 10 months ago

Based on the book CLOCK AND WATCH ESCAPEMENT MECHANICS by Mark V. Headrick (Copyright 1997) as a fine source, I try to present rigorously the essence of escapement design. The book is public (http://www.nawcc-index.net/Articles/Headrick-EscMechanics.pdf), so you can read and compare (with the book) everything I present here. Actually, you can use my projects as accurate simulations for understanding the book. I recommend you to download the book in order to use it when your computer is offline.
All parts, assemblies and simulation/animation are made with Inventor 2014, so some specific references are bonded to this software.
As you can learn from the book, there are three classical kinds of escapement mechanisms: Graham (dead-beat), Recoil and the Swiss Lever. After presenting Graham and the common recoil escapement (see https://grabcad.com/library/classic-escapement-recoil-common-1), here is the Brocot escapement. This is presented very shortly in the book (pag. 18), but enough for us to see what is the essence. The point is: „the radius of the pallet is equal to the thickness of the modified Graham pallet”.
We already have constructed the https://grabcad.com/library/classic-escapement-graham-modified-1, so now is easy. Look to the picture „Protrusions on palette.jpg” and notice the two semicircles which are placed in certain positions on the ends of the two arms of the palette. You have to look at the sketch to see the constraints (Coincident and Tangent) for both. They are extruded and can be seen in the picture „Classic Escapement - Recoil (Brocot) - 2.jpg”. Their curved faces (red) are the contact - impulse faces, as you can see in the clip.
Again, if you use Inventor (2014, 2015...), by entering Environments / Dynamic Simulation you can make your settings to change the way the system works. For instance, you can change the torque applied on the reel from 6 N mm to other value. You can also change the length of the rod from 400 mm. Watch what happens and try other values till you obtain a stable, uniform movement of the pendulum for an indefinitely long period of time.
I am curious how many of you read my descriptions. To see this, I write here a little joke. In a room from a hotel in Dublin, on a table, a Bible is open. A paragraph is underlined: „to make love with your wife on Sunday ia a sin as big as making love with the wife of your best friend”. Near the paragraph was written by hand: „tried both - big difference!”. If you enjoyed the joke, then please send me a private message to make me happy... (Note: I am disappointed - after a month after posting, no one noticed my joke!)
You can read more about the Brocot Escapement by looking to the remarkable simulation of Ken Kuo, and reading the documented description here: https://youtu.be/vh1rH6WGv60
Enjoy!