grandmother clock short pendulum swing

[bradmack]

I have a grandmother clock that someone threw out a couple of years ago. It had all the parts and I reassembled it and it worked great for a couple of years. Than the pendulum started a short swing and it started gaining time.
I have removed the all brass works but can not see what might be causing this. It has two weights and only chimes at the hour and half hour.
HELP!

[LaBounty]

Hi Bradmack and welcome to the Message Board!

Your movement is probably a Hermle and in need of service. The symptoms you describe are typical of a movement which is dirty or worn and suffering from excess friction. As the friction in the bearings increases, there is less and less power to drive the pendulum and it will eventually stop from lack of driving force.

You may find information on how to service these by using the "Search" feature but I'd suggest taking it to your local clock repair shop if you've never taken one apart before.

Good luck with it!

[bradmack]

Thanks for this information but it has been running like this for over 6 months. Not gaining more time than about 5 minutes a day.
When it started this short swing, it just all of a sudden started. I would think it would gradually shorten the swing, not all at once. Any futher thoughts?

[LaBounty]

Hey Bradmack-

The oils will dry up over time and become hard with embedded dirt. The time keeping can suddenly change when a crumb of dirt becomes dislodged and wedges in the bearing hole.

I believe the reason for the fast rate is due to dirt and wear and the solution is to have the clock movement serviced. Hermle movements which are more than 15 years old are good candidates for replacement rather than repair since these movements have plated steels and are at the end of their life. When the plating starts to let go, the bearing surfaces are too rough to transfer power up the train and it is easier to replace the movement than replace the steel.

A short-term solution would be to turn the rating nut, located at the bottom of the pendulum, 3 - 5 full turns to the left. This will lower the pendulum bob and cause your clock to run slower.

Good luck with it!