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Rolex Movement Calibre 3255
The New Generation Rolex Movement Calibre 3255

New Standards of Performance

Calibre 3255

Rolex is introducing calibre 3255, a new-generation mechanical movement with 14 patents, which sets new standards of performance for the core characteristics of a watch movement: precision, power reserve, reliability, resistance to shocks and magnetism, as well as the ease and convenience of its adjustment.

Calibre 3255’s criteria for precision in everyday wear are twice as exacting as those for an officially certified chronometer. It incorporates the new Chronergy escapement patented by Rolex, which combines high energy efficiency with great dependability. Made of nickel‑phosphorus, it is also insensitive to magnetic interference. The oscillator, the true heart of the watch, has an optimized blue Parachrom hairspring, which is also up to 10 times more precise than a traditional hairspring in case of shocks. Thanks to a new barrel architecture and the escapement’s superior efficiency, the power reserve of calibre 3255 extends to three days. This means the watch will easily continue to run from Friday evening into Monday afternoon even if not worn or wound.

Precision 2x more precise than an official chronometer

Autonomy 70 hours (+50%)

Chronergy escapement Efficiency +15%

Patents 14

New components >90%

Superlative Precision

Calibre 3255

With calibre 3255, Rolex sets a new level of chronometric precision with criteria surpassing those of COSC (the Swiss Official Chronometer Testing Institute). Rolex has developed a new methodology and high-technology equipment to test the precision of its Superlative Chronometers with tolerances that are twice as exacting as those for official certification, and under conditions that simulate the wearer’s real-life experience. These exclusive chronometer tests complement the official COSC certification, to which all Rolex movements continue to be submitted systematically, and are carried out not on the movements alone, but on the assembled watches after the movements have been cased. A specific test protocol was designed by Rolex following large-scale statistical studies to determine the actual conditions of daily wear. As a result, the Rolex chronometers equipped with movements tested according to this new methodology demonstrate superlative precision on the wrist.

The New Chronergy Escapement


The Chronergy escapement of calibre 3255, developed and patented by Rolex, is an optimized version of the Swiss lever escapement. Its energy efficiency has been enhanced while preserving its reliability.
To make it more efficient, Rolex engineers analysed the Swiss lever escapement and isolated the key parameters to be modified. The solution arrived at involved reversing the length ratios between the escape wheel teeth and the pallet stones. While the pallet stones are now only half as thick as before, the contact surfaces of the escape wheel teeth have been doubled. Moreover, the escapement elements are no longer in alignment but are slightly off-set in order to increase the lever effect.
The pallet fork and escape wheel are made in nickel‑phosphorus to be insensitive to magnetic interferences. The escape wheel has a cut-out design to make it lighter and reduce its inertia.
Together, these modifications to the geometry have increased the efficiency of the escapement by 15 per cent, contributing to almost half of calibre 3255’s enhanced power reserve.

The escapement plays a major role in how the movement functions. Its alternating beats produce the familiar "tick-tocks" of mechanical watches. Positioned between the gear train and the oscillator, it is the "key to time": the escape wheel receives raw energy from the mainspring through the gears and transmits it to the oscillator, via impulses from the pallet fork. The oscillator's regular back-and-forth motion determines the division of time which the escapement in turn transmits to the hands via the gear train.

Understanding the escapement
Rolex new Chronergy escapement



The oscillator of calibre 3255 is fitted with a blue Parachrom hairspring, patented and manufactured by Rolex in an exclusive alloy of niobium and zirconium. It is insensitive to magnetic fields and temperature variations, and up to 10 times more resilient to shocks  than traditional hairsprings. It features an optimized Rolex overcoil, enhancing the isochronism of the oscillations in any position.
The large balance wheel with variable inertia is fitted with four gold Microstella nuts enabling extremely precise regulating. Its redesigned geometry and the high-precision machining have enhanced the poise three-fold.
The oscillator is attached to a new balance staff with exclusive geometry offering added resistance to magnetic interferences. It is fitted on high-performance Paraflex shock absorbers and is held firmly in place by a traversing bridge further reinforcing shock resistance. The balance bridge features an optimized height-adjustment system and new integrated protection for the balance wheel.

The oscillator is the heart of a mechanical movement. Comprising a hairspring and a balance wheel, it is the regulating organ that determines the precision of the watch by the regularity of its oscillations. The oscillator in a Rolex watch beats eight times a second, or more than 250 million times a year. For an oscillator to maintain its regularity, it must be able to resist external factors that can disrupt its performance, such as temperature variations, shocks, magnetic fields and the varying influence of gravity in different positions.

Understanding the oscillator
Oscillator with Parachrom hairspring



The efficiency of the gear-train has been optimized. Rolex has also developed and synthesizes in-house exclusive high-performance lubricants with a considerably longer useful life and greater stability over time. Rolex is the only independent manufacturer that has developed and synthesized its own lubricants.

The gear train is the series of cogwheels that transmits energy from the barrel to the escapement. Through its different wheel sizes and gear ratios, it transforms the beats of the oscillator into the seconds, minutes and hours displayed by the hands. Correct lubrication of this mechanical assembly and high-quality lubricants are essential to ensure the proper functioning of the movement and its continued reliability over many years.

Understanding the gear train
Rolex efficient gear train



Space is at a premium inside a watch movement. To increase the capacity of the mainspring in calibre 3255 without increasing the size of the barrel housing it, Rolex decided to optimize the space inside the barrel by reducing by half the thickness of its walls. This solution represented a considerable challenge both for machining and for the production process, pushing the boundaries of the industry’s current production methods. The resulting gain in space allowed for the accommodation of a mainspring with greater capacity, thereby increasing the movement’s autonomy by more than 10 hours.

The barrel supplies energy to the movement. Inside is the mainspring whose powerful coils store the energy produced when the movement is wound, either manually or through a self-winding system. As the mainspring uncoils, it releases a continuous flow of energy which is controlled by the alternating movement of the escapement. Energy from the mainspring is transmitted to the escapement and the oscillator through the gear train. The movement’s autonomy or power reserve between windings depends therefore on how much energy the mainspring can store, and on energy efficiency, i.e. how much energy is consumed by the gear train and the escapement-oscillator assembly. Increasing autonomy means either improving the escapement's efficiency or enlarging the mainspring – or both, as Rolex has done with calibre 3255.

Understanding the barrel



Calibre 3255 is equipped with a self-winding module via a new-generation Perpetual rotor, for more rapid winding of the new high-capacity mainspring. The reversing wheel system enables winding in either direction of the weight rotation. This system, with its characteristic red wheels, has been optimized to reinforce its efficiency whatever the activity of the wearer. The now monobloc oscillating weight has been cut-out to absorb shocks. It is fitted on a ball bearing and is held at its centre by a single screw, thereby facilitating assembly.

Energy stored by the mainspring must be regularly renewed, otherwise the movement would stop once it had used up its power reserve. Traditionally, the mainspring is hand wound, via the winding crown. In 1931, Rolex played a pioneering role when it developed a self-winding system for a wristwatch, which it patented as the Perpetual rotor. This mechanism, with its half-moon-shaped oscillating weight, continually winds the mainspring using nothing more than natural wrist movements. This way it supplies the movement with a steady and "perpetual" source of energy for as long as the watch is being worn.

Understanding self-winding



Calibre 3255 e-brochure


The presidents’ watch

Rolex is introducing the new generation of its most prestigious model, the Oyster Perpetual Day-Date, featuring a modernized design with a 40 mm case as well as a new mechanical movement, calibre 3255, which sets a new standard for chronometric performance.

Rolex Day-Date 40 with Calibre 3255