This post is a bit premature for what I had planned, but given the interest in the Daniels escapement, I thought I'd get this out now.
Eventually, I hope this to be part of a series of articles on my experiences designing and building my own watches. I am presently designing a flying tourbillon with a Daniels escapement and the drawings attached are from my work analyzing and playing with this mechanism (on the computer). The drawings are not complete, but they reflect a fair bit of work. If there is interest, I will post much more later. But for now...
The image below was copied from Daniels' 1981 book "Watchmaking". It illustrates one manifestation of his coaxial escapement. The next figure shows the 3D view of the design (do not pay much attention to the figure captions as they have typos that can be misleading).
My design below is yet another manifestation of the Daniels coaxial escapement. The geometry is mirrored so that the escape wheel turns the opposite way from the one in Daniels' design (I am using this design in a tourbillon where the seconds hand is mounted on the top of the cage on the "frontside" of the watch so I must insure the second hand turns "clockwise"). The first image below shows the "guts" of the Daniels escapement. The various parts are labeled. The balance wheel has a single jewel (J5) that is directly impulsed (or kicked) by the outer escape wheel, The inner escape wheel impulses the balance via the pallet at jewel J3. This is the only purpose for the inner escape wheel. There are 2 locking jewels (J1 and J2). The pallet lever action is implemented via the balance roller jewel (J4) via the pallet fork, as in a conventional anchor or lever escapement.
The next set of drawings illustrates the action of the escapement. I'll go through it in detail. In (1) the balance is turning clockwise, the roller pin has just engaged the pallet fork and the balance is about to "unlock" the escape wheel by lifting jewel P1 off of escape wheel tooth T1. In (2), P1 was just lifted, the tension of the train (driven by the mainspring) causes the escape wheel to turn and as it turns tooth T2 on the smaller escape wheel kicks (or "impulses") the jewel pallet impulse jewel I2. Notice that this impulse is nearly tangential and there is little or no sliding friction between the tooth and the jewel. No oil is required at this point. The impulse at I2 rocks the pallet thus giving the balance wheel a boost through the fork which is engaged with the balance roller jewel. In (3) we see that when the pallet reaches the end of its travel (set by the banking pins), the locking jewel P2 is in position to intercept the outer escape wheel tooth T3 and thus stop the rotation of the wheel. The balance continues to spin in (4) reaching the end of its swing and then starting to return in the other direction. In (5) the balance is now spinning counter-clockwise, the balance roller jewel is again entering the pallet fork and the balance is about to "lift" the locking jewel P2 off of the escape wheel tooth T3. In (6) the locking tooth has just been lifted, the escape wheel starts to turn and tooth T1 on the outer escape wheel kicks (or "impulses") the balance impulse jewel I1. Again, this impulse is nearly tangential and virtually frictionless, so no oil is needed on these surfaces. At (7), the pallet reaches the other banking pin, the escape wheel is locked at P1, and the balance roller jewel is leaving the pallet fork. (8) shows the balance having swung to the other limit of travel, and then the whole series repeats again at (1).
I hope this sheds some light on the operation of a Daniels
coaxial escapement. The figures below are scans of some of Geoege Daniels' watches that employ the coaxial escapement. The first is a pocketwatch with a coaxial escapement tourbillon. The second shows a wristwatch using the same escapement (with a 4 minute tourbillon).
Finally, I show some of my work in designing a "flying" tourbillon with the Daniels escapement. The tourbillon is "flying" meaning there is no upper bridge supporting the tourbillon cage. The cage spins on a shaft constrained by small ball bearings on the underside. These provide the needed radial support for the cage. The design shows a 1 minute tourbillon and uses a Patek-style gyromax balance wheel. The balance has an incabloc shock system. Note that these drawings are very preliminary. I attempted to remove some of the hidden lines in the second labeled drawing, but there is still a lot of clutter. Eventually, this will improve. I hope to build such a watch in a pocket watch size first before attempting wristwatch-sized parts. Wish me luck!