Expert: John Newman - 9/16/2009

Question
I have a @50 year old Erhard Jauch clock. is there anywhere i can find a diagram or pictures of the clock mechanism and how they work?
We can not get the moon dial to run.
Do the weights have to be in a specific location as they are all three different in weight.
It counts the hours but will not chime.
We are looking for any schematics on the clock.

Answer
Vicki, I can't really suggest any ready reference material for solving your clock problems unless you want to study clockmaking and go through a series of lessons to understand all the functions and how they interact.  But I will give you some what I feel are excellent book resources at the end of my answer.  I don't believe I have ever been aware of working on a Jauch movement that was 50 years old, but then there is very little information on the dating of Jauch clocks.  What company manufactured your clock?
 
First, I believe the moon dial advance mechanism on the Jauch movement of that age has a tab on the hour tube.  This tab lifts a mechanism consisting of a series of connected levers that enters a tooth on the moon dial and advances it.  As the hour tube rotates every 12 hours, the moon dial is advanced twice a day.  There also should be a detent spring that lightly engages the teeth at another point to hold the moon dial in position when not being advanced.  Any misalignment of the tab or levers can result in the moon dial not advancing.  

There are specific locations for the weights.  I would need to know the model of the movement to determine the weights and locations.  Actually, it would be better if you could send a photo of the back of the movement to my shop email address below.  Even with the same model, different types of pendulums require different weights on the time train, which is the center weight.

When you say that the movement counts the hours, do you mean if you trip the hour strike mechanism?  The reason I am asking this is that under normal operation the chime plays specific notes every quarter including the hour and then the strike counts out the hour.  The hour function is dependent on the completion of the chime function.  So if the chime is not working, neither should the strike.  However, it could be that there is a wheel loose that actually drives the chime cam, and in that case the chimes would not operate.  There is an intermediate wheel on the back plate of the movement that could have a set screw loose.  Or maybe the chime hammers are not aligned so they are not hitting the rods.  There is another situation that I am not sure can happen.  Some models of movements have an hour function that is set at the beginning of the hour chime.  But I think that still the chime has to complete to release the strike.  

Last question.  How long since the clock has been serviced?  Yours is what I consider to be a modern production clock, and I recommend they be serviced every 7 to 10 years.  This includes cleaning, inspecting for worn or broken parts and repairing them, oiling and adjusting.  Again, there aren't any "schematics" for the diagnosis of internal clock problems that would normally be left to an experienced clockmaker.  If you do want to learn about the functions and diagnostics, I would suggest that you Google Clockmakers Newsletter.  The newsletter itself was discontinued last year, but the author, Steven G. Conover is still active in writing and has published some very good books, starting with "Clock Repair Basics" and on into "Chime Clock Repair" among others for advanced learning.

Let me know more about your clock.

John Newman
THE VILLAGE CLOCKSMITH
Old Prattvillage
Prattville, Alabama
klokdok@juno.com  

(General Note:  Due to the commitment I have for answering Allexperts questions and follow-up information,
and the excessive backlog at my shop, I regret that I cannot answer other questions from
this email address in a timely manner)