Urgos movements are often found in older, high-quality grandfather clocks such as Howard Miller, Ridgeway, and others. Although Urgos production stopped in the late 1990’s, many are still found in clocks manufactured before 2000, and are commonly found in clocks manufactured from the 1970’s to the 1990’s. Suppliers of similar movements claim that the movements have lifetimes of 30 years. It seems that the primary concern with these movements has been the nickel-plated pivots, which tend to wear and break down with age, resulting in acceleration of hole (bushing) wear.
It is debatable whether or not the pivots can be restored well enough to allow for long movement life post-restoration. This is the argument suppliers make for suggesting replacement movements vs. restoring the original, and perhaps it makes some sense. But replacements are not without their issues, either.
Setting the beat manually during pendulum clock setup is something that horologists have been doing for centuries. It is super critical to the proper function of a pendulum (or really, any) clock. Simply put, proper beat means the time between “tick” and “tock” is the exact same as the time between the previous “tock” and the next “tick.” If the clock beats evenly, it will continue to run. If not in beat, it may not run. This becomes more important as the clock experiences normal wear and age. Unfortunately, moving a clock with a heavy pendulum, or even allowing it to stop, can cause damage to the escape wheel teeth with rigid, manual beat setting arrangements. Thus the introduction of auto beat in modern grandfather clocks.
With auto beat, the clock may end up out of beat more easily due to the clutching action incorporated into the verge assembly. This can happen due to the clock stopping, during winding, or anything else that disturbs the pendulum. But, it is easy to reset by moving the pendulum to one extreme (either left or right inside wall of the cabinet) and then releasing the pendulum. As the pendulum settles down, the beat automatically adjusts itself, and the clock is now in beat–or close!
In the past, servicing Urgos movements has not been a major problem for us. But we recently finished one that had multiple issues prior to restoration, manifested as poor timekeeping (would run too fast regardless of pendulum bob position). All pivots cleaned up ok, thankfully, and only one had failed nickel out of the many dozens in the clock. Oddly, someone had previously installed 30 bushings (can’t imagine that all of those were needed) and not one was properly done. That was the (relatively) easy problem to solve despite being time consuming to set bushings back to center for proper gearing etc.
Next, the escape wheel was worn enough that it would not lock (just to clarify some confusion that seems to exist: these ARE dead beat escapements, but are also auto beat). Simply adjusting the verge depth led to clearance problems. The entrance pallet also showed absolutely no impulse—escape wheel teeth just dropped off the locking face. Someone had been previously grinding at it, obviously.
The first part of the solution was to cut a new escape wheel. It turns out it is quite possible to fabricate replacement auto beat wheels for Urgos, but it takes some manipulation of the cutter and multiple passes to get it right. The PP Thornton D Graham Dead Beat cutter was used. The wheel was sized to OD of 30.1mm in anticipation of having to re-grind and surface the impulse face angle on the entrance side. With the new wheel and proper entrance angle, lock and clearance were achieved. So far, so good.
During test run, the auto beat would drift out of beat on its own. It turns out that the auto beat clutch had worn to be much too loose. The retaining bushing on the pallet assembly was successfully staked down to get it tight enough to function. While very supportive of using weight measurements to test clutch function–and actually prefer that approach, the correct tightness is that which allows auto beat to function, but prevents it from slipping during normal operation. (Will post a measurement on it once disassembled the setup for transport.) The additional advantage of auto beat is it prevents tooth damage when the clock stops or when it is wound. But the clutch adjustment has to be correct.
The last issue was deceiving. The original suspension spring/block was literally destroyed, so a replacement was ordered. Since the same style movement was used on a variety of clock/pendulum combinations, it was necessary for Urgos to incorporate a pendulum anti-wobble feature in the crutch design (it’s the upper fork in the dual fork crutch). This can be no end of grief if it is mis-aligned, and/or if the suspension block is too tight in the anti-wobble fork. Lesson learned: always check for clearance/alignment in this fork without the pendulum to assure there is no binding, which will kill amplitude. Too loose is no good either, since it allows pendulum wobble. A paper thickness clearance between the suspension block and anti-wobble fork is sufficient.
Clearly, auto beat is a necessary function with modern grandfather clocks. Unfortunately, the Urgos verge and its small geometry tends to exaggerate any errors or imperfections in the auto beat function in comparison to, for example, Kieninger’s auto beat escapement design. While the auto beat doesn’t yield an accuracy level to my ear’s satisfaction, it is close enough to keep the clock running if it gets out of adjustment either through winding, clock stopping, or something getting bumped. Many customers use it any time the clock stops, whether needed or not, and regardless of guidance. So, it MUST work.