Expert: Martin Meyer - 2/2/2008

Question
QUESTION: I have a french movement with front escapement.There is a small round label imprinted on the back that says MEDAILLE DE BRONZE L. MARTI & CO. It is about 3-3/4" dia. There is a horizontal shaft at the top of the movement that protrudes through the face with a square end at the face and a 10-tooth gear at the rear. This gear meshes with a 17-tooth gear on a vertical threaded shaft. This mechanism is used to regulate the clock. I need the complete mechanism with the horizontal and vertical shaft with the adjusting assembly. Can you advise where I can get this assembly? I attached a picture of the movement.I can send other pictures of the movement and of this regulating assembly from another movement that is similar. Thank you

ANSWER: Hi Dick,
    Obtaining a compatible regulating assembly could be difficult. These parts are not available from materials houses. You may have to find a similar "junk" movement on a service such as Ebay. Merritts Antiques also has a Clock Shop (reachable by phone) which has many parts from old clocks available. Merritts Antiques website will give the phone number. The exact number of teeth on the two gears is not a critical factor, as long as they engage each other without jamming. You may also have to do some modification of the shaft lengths, if you can get a regulating assembly that is similar, but not identical, to the original.

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QUESTION: Thanks for the information. I will contact Merritts. I do have another question. Can you tell me what the pendulum looks like and the length?

Answer
Hi Dick,
    French pendulums usually have a rigid steel rod with a brass double-pronged hook threaded on at the top. They have a small (1 1/2" approx.) solid brass bob. The bob doesn't usually have a regulating nut at the bottom, but rather attaches to the rod with a set screw through the bob. There is often a decorative brass bottom piece on the rod.
    The length of the pendulum depends entirely on the individual clock. Pendulum length determines the rate at which the clock runs; the longer the pendulum, the slower the rate. I usually start out with a rod just short enough that it doesn't hit the bottom of the clock. The I run the clock with the regulating unit (a small shaft on the dial of clock, usually near the "12") set midway in its adjustment range. I keep track of the timekeeping, raising the bob as necessary until the clock keeps fairly accurate time. Then I cut off most of the excess of the rod below the bob, and replace the decorative bottom piece on the rod.