An adjustable deadbeat

Wha'dju call me?

Well let's explain.

In our last episode your local horologist was just about to discuss the removal and examination of the wheel train of the single weight Vienna Regulator. 

The wheels looked to be in good shape but YLH was focused on the clock's escapement and in particular, its anchor. Recent readers will recall that an anchor engages with the teeth of the escape wheel and together they form the escapement.

The escapement is the heart of the mechanical clock and fascinates your amateur d'horologie. 

The anchor is the principal component of the escapement that drives the pendulum. The two major types of anchors are the recoil (a very early form of anchor and most commonly seen in mass-produced clocks) and the deadbeat (a later variant and more prevalent in European and higher quality clocks).

There are many other types of escapements, some very exotic.

Frequently attributed to George Graham, the deadbeat was actually created by Richard Towneley in 1675. In 1715 Graham modified and refined Towneley's design and his improvements drove the much more rapid adoption of the deadbeat in many horology circles over the earlier recoil anchor. So much so that the name of the escapement is classically associated with Graham.

Its principal improvement was to eliminate the energy sapping of the recoiling action.

Here's an animation of a recoil escapement that clearly shows the escape wheel... er... recoiling.

from Wikipedia

The anchor is the gray inverted V. It has two pallets (arms) and their ends which collide with the escape wheel teeth are the pallet faces.

Notice how the teeth of the escape wheel hit each pallet face and, as they slide over it, the escape wheel actually turns slightly backwards before advancing forward. 

While the escape wheel clearly rotates forward overall, this recoil design results in the entire wheel train of the clock getting pushed ever so slightly backwards with every tick of the clock.

To be fair the recoil escapement is actually still quite popular and modern versions are cheap to make (like the strip style recoil anchor found in most American clocks). The energy inefficiency of the recoil is often simply accommodated by having clocks with more powerful mainsprings.

But really precise clocks needed to eliminate that recoil and Towneley/Graham found a way to change the design of the pallet faces to do so. 

from Wikimedia

No recoil. 

The truly exhausted intrepid reader may have gotten through YLH's posting a while back about the double tick issue in Charlotte's Ingraham Regulator, and in particular the nerdy details about the locking action of the escapement. 

Look above again and see how a tooth lands on the face of a pallet and slides along that face. That is the locking action. 

When the escape wheel teeth lock (land and slide on the pallet face), the escape wheel itself stops "dead" while the tooth is sliding on the locking face of the pallet.

By changing the geometry of those locking faces of the pallets Graham created an escapement design that eliminated recoil.

The red areas in this diagram show the locking faces of the pallets of this anchor.

from Berkeley

Here's a beautiful model example of a Graham deadbeat from the University of Aberdeen.

Well this new deadbeat escapement was met with great fanfare in the horology world.

But its dependence on the exacting geometry of those pallet faces did make it hard to finely adjust or repair if there was damage.

This graphic used in an earlier post shows both the locking faces and the impulse faces of a pallet. The curvature of the locking face and the angle of the lift (impulse) faces have to be very precise.

from Berkeley

The horologically obsessed amongst you can actually experiment by virtually adjusting different elements of the deadbeat escapement and seeing the results on its action in this Wolfram project. 

Uh Doctor Clock this is all confusing very interesting but what does it have to do with our Vienna?

Ah.

Full circle now.

Our Vienna has a very particular kind of deadbeat escapement known as a Vulliamy.

Not to be confused with his father, Benjamin Vulliamy, Benjamin Lewis Vulliamy invented a modestly titled but highly reliable adaptation of the deadbeat escapement. 

More specifically he created a deadbeat with adjustable pallets on the anchor. See above... the pallets are separate steel inserts held down by screws.

Benjamin Lewis Vulliamy, a fourth generation British clockmaker, was kind of a big deal...

"...was the last of the great Vulliamy family of Royal clockmakers and five-times Master of the Clockmakers’ Company. He was Royal Clockmaker to King George IV, King William IV and Queen Victoria and the driving force behind the formation of the Clockmakers Library and Collection – now Clockmakers’ Museum – from 1814 onwards."  - Wind & Wound

If an intrepid horology fan were to hop on jet over to London before the end of this year they could take in a fine exhibition of Vulliamy the son's work in the Clockmaker's Museum (housed in the British Science Museum).

Vulliamy wrote a long treatise about his escapement that is freely available for all you escapement history nerds out there.

Here is an animation of one in action. 

Escapements with adjustable pallets became hugely popular with "continental" clockmakers as the Brits would say (read German/Viennese) and are classically seen in those like our Vienna Regulator.

Why so popular?

Well in just two sentences of that treatise Vulliamy lays out both the problem/limitation of the traditional design of the deadbeat escapement (adjusting the pallets means filing or bending the arms of the anchor) and his solution (adjustable pallets).

And sure enough, one of these escapements had been unknowingly observed a few years ago by this horological hoarder in a Deutsche Uhrenfabrik AKA DUFA tall case clock. 

An extra wonderful tidbit: in the charming introduction to the treatise Vulliamy takes a shot at the patent process (perhaps because apparently he was unable to obtain one for his escapement - YLH saw this somewhere and now can't find the reference!):

"I have always considered the taking out of patents for all matters connected with science as a thing desirable to be avoided ; and the applying the word patent, where, in fact, no patent was ever obtained, or even caveat entered, as an excellent illustration of the puff oblique. Yet this is done daily ; I had almost said hourly. Patents are very proper for improvements in articles of general traffic, in which, from their great facility of execution, an interest cannot be secured in any other way ; such as corkscrews, snuffers, buttons, and others of a similar description : and the individual who employs this species of monopoly for the sake of any real or supposed pecuniary advantage, must be content to relinquish the station of a man of science for that of a general manufacturer."

The puff oblique!

Google that and you get "in the context of makeup typically refers to a makeup sponge with an oblique (angled or slanted) cut, often used for blending and applying foundation, concealer, or other makeup products." 

Fantastic.

The things you get to enjoy doing research on escapements.

In fact there were several other things YLH got to discover and learn about with our Viennese friend.

Including the fact that this clock is probably not from Vienna. 

Nor even Austria.

What!?

Tune in next time and enjoy the magic.