What Is A Fusee Pocket Watch Anyway?

by admin on June 8, 2012

I get asked a lot "what makes a pocket watch a fusee pocket watch?". The simple answer is that a fusee pocket watch uses a different gear mechanism and ratio to regulate the power and the speed as the spring in your pocket watch winds down.

the fusee pocket watches design dates all the way back to the Leonardo Da Vinci himself who is said to be the father of the fusee pocket watch design. Leonardo Da Vinci designed the fusee model as a way to better regulate the power in the mainspring making it possible for a clock to run at the same basic speed as the spring that is unwinding. This design improved the reliability and time keeping ability of the watches and clicks that used this design.

Fusee watch design Leonardo Da VinciBefore the fusee pocket watch design came about the mainspring normally had less power the further the watch would wind down. The fusee design changed the gear ratios which allowed the mainspring to stay tense even as the watches wound down. There were further advancements made of course which eventually made the fusee design obsolete. Around the year 1850 American pocket watches started using hairsprings and balance wheels which changed the way pocket watches were made.

Most fusee pocket watches need a key to wind them up(counter clockwise). It is very easy to harm your fusee poskcet watch if you attempt to wind it in the wrong direction or if you attempt to over wind your watch. Over winding is probably one of the more average issues we find with fusee pocket watches that we come across today.

How A Fusee Pocket Watch Works

On a fusee pocket watch the mainspring is wound around a solid axle inside the round box(barrel). It is the force of this movement that in turn winds up the barrel. The barrel then turns your fusee by pulling on the chain, which moves the gears.

The fusee gear powers the wheel train(typically the center wheel). A ratcheting system prevents backward movement while winding. If you attempt to force the winding in the wrong direction you will break something so be careful.

Disadvantages Of Fusee Pocket Watch Design

Fusee Watch Design With CordWe can all agree that for its time the fusee design was a great mainspring compensator. The primary drawbacks of the fusee design were its cost and the ability to adjust. As well as a few other major disadvantages which include:

    • The design was bulky and made watches much thicker.
    • When the fusee chain would break it would cause a lot of extra damage from the force of the broken chain.



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