Dr. Ito's thorough analysis of mechanical watches!! Vol.32 ~ About screw-down crowns and pushers

Good evening, everyone!

This column discusses mechanical watches from an engineer's perspective. For the 32nd installment, I will be discussing:

"Screw-Down Crowns and Pushers"

I will be talking about this topic.

Humidity and moisture are major enemies of mechanical watch movements. They directly lead to internal component malfunctions and must be avoided at all costs.

To combat these enemies, many waterproof watches, including Rolex, employ "screw-down" crowns and pushers.

This time, I will explain the structure, precautions for use, and frequently misunderstood points about screw-down crowns and pushers, which are crucial components for maintaining a watch's water resistance.

What is a screw-down crown?

The "screw-down crown" was adopted as a key feature when Rolex developed the world's first completely waterproof wristwatch, the "Oyster," in 1926.

While regular crowns can be operated directly, screw-down crowns are designed to be screwed into the case, effectively preventing water and dust from entering through the crown. Therefore, the crown must be unscrewed before operation.

Rolex uses two types of crown mechanisms depending on the purpose and model.

One is the "Twinlock." It is primarily used in models like the Datejust and Explorer, characterized by its smaller crown diameter.

The other is the "Triplock," primarily used in professional models with high water resistance, such as the Submariner and Sea-Dweller.

It is characterized by a larger crown diameter and three dots below the crown emblem.

The structural difference between Twinlock and Triplock is that Twinlock maintains water resistance with two gaskets, while Triplock uses three (now four) gaskets.

While Twinlock provides sufficient water resistance, Triplock offers more peace of mind when higher water pressure resistance is required.

Incidentally, a non-screw-down crown typically uses a single gasket to prevent water and dust intrusion. You could call it a "single-lock crown."

Even if you forget to tighten a screw-down crown, one gasket will still function, similar to a single-lock crown, so it's not immediately non-waterproof and water or dust won't get inside right away.

What is a screw-down pusher?

A screw-down pusher is a mechanism where the chronograph operation button is tightened by screwing it in, which prevents accidental operation and enhances water resistance.

Rolex first adopted screw-down pushers for the manual-winding Daytona "Ref. 6240," making it the first wristwatch to feature them.

All Daytona models from the final manual-winding Daytona "Ref. 6263/6265" onwards are equipped with these screw-down pushers, and the dial bears the "OYSTER" inscription.

Here's something I definitely want you to know: the structural difference between screw-down crowns and screw-down pushers.

While crowns improve airtightness by being screwed in, pushers actually don't have gaskets in their screw-down sections, so their airtightness doesn't change before or after screwing. So why are they screw-down? It's to "prevent accidental operation underwater."

With non-screw-down pushers, if you accidentally touch the push button underwater, water pressure can cause water to enter the case. To prevent this, the push button cannot be pressed until the screw-down lock is released.

Many people misunderstand this point, so I hope you'll remember it from now on.

Therefore, there's no need to screw down the pusher with excessive force; simply screwing it until it stops lightly is sufficient.

Summary

How was that?

During this rainy season, many of you might be concerned about your watch's water resistance, so I decided to talk about crowns and pushers.

Rest assured that with a good understanding of how to use them and regular maintenance, you can confidently wear your luxury watch even during the rainy season.

I hope this article provides useful information and sparks even a little more interest in luxury watches! Also, if you have any questions, please feel free to ask me directly, and I will be happy to answer them. We look forward to your visit and inquiries.

Stay tuned for the next installment! See you then!