When it comes to water resistance, the bullet-proof case and solid crystal come after the winding crown. This essential part of the watch is not critical just because it serves for setting the time and other important features, but because this system defines the waterproofness of the timepiece. By using it you open the case and create an access point for dust and water, both of these outside factors are huge enemies of a high end mechanical self-winding movement. This is the reason why the winding crown needs to have its own sealing system, one that is capable of perfectly locking the case and keep its interior clean.
Rolex is one of the brands that pay great attention to this aspect. Its crowns feature two patented sealing systems called twinlock and triplelock. Both types imply a threaded screw-in crown that seals against a rubber gasket making the watch more water tight. In case you were wondering what’s the point of having two types of locking systems, let me clarify this right away. The water resistance required for a watch is what determines if the winding crown should be a twinlock or a triplelock one.
The Twinlock crown is used for timepieces that are waterproofed to 100 meters/300 feet. You can easily recognize the type of system used by looking at the top of the stem. If it has the Rolex crown logo with a simple dash “-“ or two dots “..” then this means that the watch comes with a twinlock crown. The internals of this complex sealing system uses two rubber gaskets. One rubber o-seal is located inside the watch’s tube and the other one is at the interior of the actual gasket that presses against the threaded tube added to the watch’s case. By using these two gaskets system, water and dust are kept outside the case. A very interesting fact is that even if the crown is unscrewed, the gasket located inside the watch’s tube prevents water from entering the case.
The triplock crown system was designed to ensure waterproofness to depths of 300 meters/1000 feet. Rolex uses 10 different components for creating this system and four gaskets. You can recognize a Rolex watch that has the triplock stem by taking a closer look at the winding crown. This is larger than the Twinlock crown and has three dots under the small Rolex crown logo positioned on its top part. The architecture of the triplelock winding crown system implies four rubber o-ring seals and a bigger case tube. These manage to guarantee a higher level of water resistance. When the stem is unscrewed you can easily view the first gasket as it comprises the exterior of the winding tube, but is positioned just at the interior of the crown. Just like on the twinlock crown system, the second rubber gasket is located inside the crown and it presses against the tube of the case. The other two gaskets are at the interior of the case tube. The thicker threaded case tube and the four rubber seals offer a higher level of water resistance for those who are passionate by extreme diving.
There is nothing simple or ordinary about the patented Rolex twinlock and triplelock winding crown systems. These extremely complex and unique water resistance features have been developed and manufactured for those who need a reliable diving instrument for exploring the deepest parts of the ocean.