Expert: Martin Meyer - 7/27/2009

Question
Hello:
Would you happen to know where we can purchase a lyre pendulum for a Hermle 451-050 85cm. Our problem is the bob size as our middle weigth is only 4.7lbs.  We were told with the lower weight we would need a bob under 6.5" but we are unable to find a lyre pendulum that meets these specs. all seem to have the larger bob so we are unsure as to what to do.  Any help would be greatly appreciated!
Thank you,
Joe & Mary  

Answer
Hi Joe & Mary,

There are a number of issues here, and pendulums have several dimensions to be considered. First, the length of the pendulum is the most critical factor. Most pendulums for 85cm. Hermle movements have small bobs, because this is the shortest pendulum length in Hermle longcase movements. So, you must purchase the correct length pendulum for an 85cm. Hermle movement, which has an actual length of 30". The only pendulum for an 85cm. movement listed in the Blackforestimports.com catalog (your best source for Hermle parts and information) has a bob diameter of 6.5". This should meet your requirements.

Next, if you have the correct set of weights, you should have two 6.6lb. and one 4.7lb. The 4.7lb goes on the left (looking at the clock), which is the hour strike train. If you have two 4.7lb and one 6.6lb weights, your clock was originally intended to use a wood stick (not a lyre) pendulum, and must not have a seconds hand. Another option, therefore, as long as your clock does not have a seconds hand, would be to purchase a wood stick pendulum.

But, what I am wondering is why you are not considering simply adding weight to the center (time train) weight. If 1)your pendulum is the correct length for an 85cm movement, and 2)the disk is not so large that it hits the sides of the clock when it swings, then this would seem to be the easiest option. One thing to consider with this option is that the weight filler (insert) that you purchase will fit inside the weight shell. Otherwise, you will need to purchase a set of complete weights, that is, weight shells with fillers. Unfortunately, weight shells are far from standardized, and it is not uncommon to find that you have a weight filler that is just a bit too large to fit in the shell. Black Forest Imports also supplies weight fillers and complete weight sets.  http://www.clockmasteronline.com