Mainsprings in New Haven Long Drop Clock Movement

I recently overhauled this movement belonging to a New Haven wall clock.

Time mainspring: The original time mainspring was broken, and measured 3/4 inch wide by 0.018 inch thick. The replacement is 3/4 by 0.0165 by 96 inches, Merritt’s P-1956.

Strike mainspring: The movement came into the shop with a 3/4 by 0.0142 inch mainspring! It may have been original, but it had a jerky action after cleaning and lubrication. The replacement spring is 3/4 x 0.0155 inch thick (Merritt’s P-1496 in the orange and red box).

The video below shows the escapement action when the time mainspring is run down 7 1/2 days and then fully wound. The motion is sufficient but not excessive.

Repair job 4926.


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