Expert: Martin Meyer - 1/5/2008

Question
Martin,

I have inheritanted an clock problem. Not having done any clock for over 30 my memory is a bit fuzzy.

I have a Chinese movement Pendulum wall clock. Reasonable late manufacture. about 5 years.

The problem as it arrived as I now know it:
The owner arrived home on day to find the clock had stopped. He decided to clean it. He did this by washing kerosene and then spraying it with CRC. He latter admitted to me that he had moved the escape government. The clock since then has constantly gained about 20 minutes per day.

My wife dobbed me in and I got the job of rectifying the problem assuming was just one cleaning the clock and setting the beat. I washed the clock in a proper solvent and Including letting it run down in the solvent at least three times, I then oiled the clock with new "CLOCK OIL", I then set the clock up on my work bench using a sprit level.
in order to regulate the clock. The clock continued to gain about twenty minutes per day. Adjusting the pendulum made no difference. I spent some(a lot) time checking the escape mechanism. Watching the pendulum it has a very short swing. The escape mechanism in my onpnion is working properly and the clock will run for a number of days.I think we used to refer to this as "short beating", but I am unable to remember how to rectify the problem.

Sorry about the long letter but I I wanted you to know all the facts.

Regards
Sid Prendergast  

Answer
Hi Sid,
    There are so many possible problems here that I can't give a very complete answer.
    Only complete disassembly cleaning is effective for a clock movement. The use of kerosene and other improper solvents or lubricants may certainly have aggravated the problem.
    It is very unfortunate that the owner fooled around with the escapement. The fact that the clock gains significant time and proper adjustment of the pendulum doesn't help, indicates that the verge pallets may be out of adjustment and allowing several escape wheel teeth to pass on a single "tick". This can happen only occasionally, thus making it difficult to observe. The short swing of the pendulum also supports this possibility; if the verge is set too high, not only can several escape wheel teeth pass at one time but, additonally, its pallets or pins may be hitting the escape wheel teeth on the tip of the impulse faces, rather than on the locking faces, thus providing insufficient power to swing the pendulum. This problem could also account for the clock's only running a few days, rather than its full winding period.
    Only a fully disassembly can correct the cleaning problems. As for the escapement problems, I would observe very carefully where the pallets or pins are first contacting the escape wheel for every one of the escape wheel teeth. If the verge is too high, and the pallets are hitting the escape teeth on their tips, or anywhere on the impulse face, so that it misses the locking face, the verge must be lowered. After adjusting the verge for sufficient depth, of course, you must then adjust it for equal depth of locking between the entrance and exit pallets. You should attempt to get the locking depth equal for the two pallets, and as deep as possible that will still release every tooth on the escape wheel.
    All this is assuming that you are dealing with a deadbeat escapement. If you have a recoil escapement, there are no separate locking and impulse faces, so you need only adjust the verge so that the pallets are contacting the escape teeth as deeply as possible without locking up on any  escape tooth.