Expert: Martin Meyer - 2/20/2008

Question
QUESTION: I thought my son had pulled the weights to tight on our circa late 70's Hermle grandfather clock. I took the clock apart to readjust the chains on the weights. In the process, I broke off the pendulum hanger and cannot for the life of me figure out how to put back on. I've looked for photos of the back of the movement and came up empty. Descriptions of orig. assembly say there should be two appendages(?) from the back of the movement, but I only see one. Can you help?

ANSWER: Hi Marianne,
    It is possible that the suspension spring broke when you were working on the clock. This would make it impossible to reconnect the pendulum assembly.
    The way the pendulum hooks up is as follows: the top hook on the pendulum connects to a brass piece about 6 inches long (the "pendulum leader"). The top of the leader connects to a small part called the suspension spring. This part has 2 small flat leaves connected by "blocks", flat square metal or plastic parts. One or both of the suspension spring leaves sometimes breaks. If only one is broken, it may not be readily apparent, and you can check it by touching each leaf with a pencil tip to see if it connected to both the top and bottom blocks. If it is broken, it must be replaced with the exactly correct size spring. If there is a part missing or broken, this is probably it. Finally, there is a hole through the leader; you will see another flat brass strip coming out of the clock movement, going back an inch or so, then bending to go down vertically, where it ends in a round horizontal post about an inch long. This post must go through the hole in the leader. This is the complete pendulum set up and everything must be just as described.
    Replacement suspension springs are available from from clock supply houses like Timesavers, Merritts Antiques or Empire Clock.


---------- FOLLOW-UP ----------

QUESTION: You're correct. The suspension spring is broken. How do I remove the old one. The pin holding it to the top doesn't seem to move. Do I measure the width(7mm)or top to bottom to replace? Thanks:)

Answer
Hi Marianne,
    If the suspension spring is held by a pin rather than a screw, it is a taper pin. Look closely at the pin to determine which end is larger, then pull the pin out by the large end. These pins are sometimes quite tight, and you may need to work it back and forth with a small pliers to loosen it up enough to remove.
    The dimensions of the suspension spring involve more than just the length. The best way to replace it is to get a printed catalog from Timesavers or Merritts Antiques. The illustrations of the suspension springs are actual size, and you can lay the two pieces of the broken spring on the pictures to match up with a spring of the correct size and dimensions. Unfortunately, this method does not work for the online catalogs, due to variations in screen resolution among different computers.