How Much Weight Does a 30 Hour O.G. Clock Need?

June 30, 2009 | By | 1 Reply More

Connecticut type American antique clocks are known for being over-powered. The one-day clocks often have more than 3 times the least amount of power necessary to run the clock.

One of my Chauncey Jerome 30 hour OG clocks was missing its weights when I bought it, and so I experimented with weights. I found that the time train of the clock would run reliably on 1 pound! (Normally these clocks have about 3 to 3.5 pounds on the time side). The strike weight usually weighs around 2.5 to 3 pounds.

I recently repaired an early Seth Thomas 30 hour Ogee. The weights that were with the clock when I received it are 2 pounds 9 ounces and 2 pounds 10 ounces. They look old and match each other in appearance, but there is no way to know if they are original to the clock. The strike sounds fine with this amount of weight, and the pendulum and escapement take an excellent motion. Here is a video showing the escapement in operation. Note the generous amount of overswing or supplementary arc (how much further the verge moves after an escape wheel tooth lands on one of the pallets):

This clock will run for a short time with a 7 ounce weight on the time side, with almost no overswing. There is noticeable overswing with 9.8 ounces of weight, and with 1 pound weight the overswing is small, but enough. With 1 pound, 12 ounces, the overswing is quite good. Of course, a clock movement must be in excellent condition to run with this little weight.

The striking sounds a little slow, but acceptable, with 1 pound 12 ounces of weight. The striking will run with 1 pound of weight, but it sounds WAY too slow.

I plan to wind this clock daily (it is on a workbench at my clock shop), and will run it with a 1 pound time weight and a 1 pound 12 ounce strike weight, to reduce wear in the movement.

Update

From June  30, 2009 to February 10, 2010, it ran continuously on the 9.8 ounce time weight. Then, it would occasionally stop around 10 minutes before the hour (when the strike levers are lifting). On February 13, I started running the clock with a 15.6 ounce (440 gram) weight.

9-21-11: It was stalling as the time approached the hour, just beforre warning. I am not running it with the original weights: 2 pounds 9 ounces for the striking, and 2 pounds 10 ounces for the time.


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Category: American Clock Repair

Last updated: September 27, 2011

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  1. Bill says:

    Note: The clock has run with a 9.8 ounce weight on the time side for a week.

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