How do Rolex watches spin without batteries?

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How do Rolex watches spin without batteries?

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They are wound which tightens a coiled spring which stores energy in the spring which slowly releases the energy over time powering the watch.

As three mechanical engineering majors at California Polytechnic State University San Luis Obispo, we will be using prior course knowledge and extensive research to explain the theory and design behind the perpetual motion technology of Rolex watches.

Rolex is a Swiss luxury watch manufacturer based in Geneva, Switzerland. Rolex watches are known for their elegance, visual appeal and bank-breaking price tag. However, the true value of the Rolex lies beneath the surface. In [mechanical watches](https://jackmasonbrand.com/blogs/news/perpetual-motion-watch-money-well-spent), there is a mainspring which powers the spinning motion of the watch’s hands. But, once the mainspring is completely unwound, there is no more energy to power the watch. In the past, mechanical watch users had to wind up their watch at least once per day in order to maintain time-telling ability.

Rolex solved this problem, becoming the first company to create innovative watches that power themselves. They created the first autonomous watch mechanism in 1931, debuting the system in the [Rolex Oyster.](https://www.rolex.com/about-rolex-watches/1926-1945.html) [The Rolex Oyster](https://www.rolex.com/watches/oyster-perpetual.html?ef_id=CjwKCAiAsOmABhAwEiwAEBR0ZiHpRe79VSTBElJbJVXVoKd6b6YLowtoK4xLC1QOMCai-soT1upqwRoCAKcQAvD_BwE:G:s&s_kwcid=AL!141!3!407381912557!e!!g!!rolex%20oyster%20perpetual) was able to power itself using perpetual movement. [Perpetual movement](https://www.collinsdictionary.com/us/dictionary/english/perpetual-motion) refers to the ability of a device to continue in motion forever, with no additional energy input required to maintain it. Rolex adopted perpetual movement into all of their modern watches which are now designed for optimal precision, waterproofness, and self-winding capabilities.

The [self-winding capabilities of a Rolex watch](https://www.bobswatches.com/watch-resources/perpetual-movement#:~:text=Invented%20by%20Rolex%20in%201931%2C%20the%20perpetual%20motion,watch%20will%20keep%20it%20wound%20and%20running%20precisely) are a result of the activity of the wrist. That external movement causes the rotor to rotate back and forth, thus winding the mainspring that powers the watch. Put simply, the watch runs on the energy provided by the motion of the wearer rather than manual winding. The perpetual motion mechanism consists of a half-moon-shaped oscillating weight rotating freely in both directions. The oscillating weight keeps the mainspring under continuous tension, providing the watch with a constant and stable source of energy. Thus, just wearing the watch will keep it wound and running precisely.

The price of a Rolex comes with a masterpiece of precision engineering and design that allow its wearers to keep track of time without having to worry about recalibration. Rolex has designed an exceptional system to create perpetual motion in their timepieces.

There are two key mechanisms that make a watch work.

The first is what’s known as an [escapement](https://en.wikipedia.org/wiki/Escapement). This is a device that allows a very slow unwinding of a spring, harvesting a bit of that spring’s energy with each tick. That’s the device that governs the actual ticking action of a watch.

The second is a [balance wheel](https://en.wikipedia.org/wiki/Balance_wheel). This is a lot like a pendulum, but instead of a weight that sways back and forth and is pulled towards the center by gravity (as in a grandfather clock) it’s a ring with weights that spins forward and in reverse, being pulled back into position by a spring. The period of this oscillation is extremely consistent and is based on the stiffness of the spring and the mass of the wheel.

Those two pieces can be combined to keep time: the balance wheel oscillates forward and reverse, with each half stroke allowing the escapement to advance a half tick. A stiff spring gives the balance wheel a small kick as the escapement advances, making sure the balance wheel doesn’t stop. As the escapement advances it is hooked up to progressive gears which convert the frequency of the ticks into the motion of the second, minute, hour, and date indicators.

There are various refinements to this design that super luxury watchmakers like Rolex use, but the fundamental concept remains the same.