RM 025

Manual Winding Tourbillon Chronograph Diver's watch

‘Our technical-aesthetic credo can be summarised simply: untrammelled creativity. Even if the results are sometimes astonishing or disconcerting. We felt like tackling the roundness of the circle. And we found our technical manifesto in our plans to create a diver’s watch. Our commitment to a particular shape is never without its reasons. The artistic motivation is always propelled by technical creation with a specific use in mind.’

RM 025

CREATED FOR EXTREME CONDITIONS

The extreme conditions of submarine use called for the design and construction of an extreme technical product. As an instrument involved in actually protecting the life of its user, the technology here demanded high performance, of course, with the added parameters of safety, reliability, durability and ergonomics.

RM 025 TOURBILLON CHRONOGRAPH DIVER'S WATCH

CALIBRE RM025

Manual winding tourbillon movement with hours, minutes, seconds, chronograph, 30-minute totaliser, power-reserve indicator, torque and function indicators.

POWER RESERVE

Circa 50 hours (± 10%), 45 hours without chronograph running.
Actual power reserve results will depend on chronograph usage.

CARBON NANOFIBRE BASEPLATE

This is an isotropic composite material created from carbon nanofibres moulded under a pressure of 7,500 N/cm2 at a temperature of 2,000˚C, resulting in a material with high mechanical, physical and chemical stability in all directions.
The ribbed perimeter of the movement’s baseplate ensures optimal rigidity of the baseplate and bridges.

Carbon nanofibre composites such as this are amorphous, chemically neutral and dimensionally constant within a very wide range of operating temperatures, including those outside of normal experience. This stability ensures the greatest possible integrity of the movement’s going train under all conditions.

CARBON NANOFIBRE BASEPLATE

BRIDGES MADE OF GRADE 5 TITANIUM

Grade 5 titanium is a biocompatible, highly corrosion-resistant and remarkably rigid alloy composed of 90% titanium, 6% aluminium and 4% vanadium. This combination further increases the material’s mechanical properties, which explains its frequent use in the aerospace, aeronautics and automobile industries.

CHRONOGRAPH

The modern architecture of this movement allows the consistent and rational arrangement of its constituent parts, avoiding unnecessary superimpositions and permitting the best possible use of available functions thanks to technical solutions. For example, research was conducted into the geometric design of the column wheel that controls the different levers to ensure the perfect, long-term simultaneity of the functions, a feature essential for a high-performance split-seconds chronograph. This design was implemented in order to achieve a high degree of continuity in the settings with an unfailing repeatability of functions.

FUNCTION INDICATOR

In a manner similar to a car’s gearbox, the function indicator makes it possible to identify the winding, neutral and hand-setting positions as the crown is pulled out. The active position is indicated via a hand at 4 o’clock that indicates the function as follows: W (Winding) – N (Neutral) – H (Hands).

FUNCTION INDICATOR

POWER-RESERVE INDICATOR

The power-reserve indicator shows the number of hours of energy left in the mainspring before the watch must be wound again.

TORQUE INDICATOR

This indicator supplies information about the mainspring’s tension, thus permitting an optimisation of the movement’s chronometric functioning. Below 53 Nmm, the spring is considered too slack, while above 65 Nmm, excess tension in the spring can adversely affect the mechanism’s operation, or actually endanger it.

RM 025

FREE-SPRUNG BALANCE WITH VARIABLE INERTIA

The free-sprung balance offers better reliability in the event of shocks, movement assembly or disassembly, and also guarantees better chronometric results over time. The regulator index is eliminated, and a more accurate and repeatable calibration is possible thanks to 4 small adjustable weights located directly on the balance.

FAST-ROTATING BARREL (6 hours per revolution instead of 7.5 hours)

This type of barrel provides the following advantages:
• The phenomenon of periodic internal mainspring adhesion is significantly diminished, thereby increasing performance.
• Provision of an excellent mainspring delta curve with an ideal power reserve/performance and regularity ratio.

MOVEMENT CHARACTERISTICS

Movement diameter: 38.95 mm
Thickness: 8.12 mm
Tourbillon diameter: 12.30 mm
Number of jewels: 30, set in white gold chatons
Balance: Glucydur®, 2 arms, 4 setting screws, moment of inertia 10 mg•cm2, angle of lift 53°
Frequency: 21,600 vph (3 Hz)
Balance spring: elinvar by Nivarox®
Shock protection: KIF Elastor KE 160 B28
Barrel shaft: nickel-free Chronifer® (DIN x 46 Cr 13 + S) with the following characteristics: stainless – antimagnetic – suitable for tempering

MOVEMENT CHARACTERISTICS

BEZEL

This component is constructed of three layers, connected using 22 screws, and turns unidirectionally per ISO 6425 norms to avoid timing miscalculations. The use of an additional screwed system attaching the bezel to the watchcase makes it absolutely stable, as well as impossible to inadvertently dislocate or loosen. In addition, the use of screws makes possible perfect adjustment since the bezel is not tensioned into position.
For clearer visibility under murky conditions, starting at 12 o’clock, the five-minute markers of the first quarter are highlighted in red.

CASE

The watch is water resistant to 30 atmospheres (300 metres) per ISO 6425 diver’s watch norms. This is achieved within a unique, curved, tripartite case design using torque screws that can be individually and precisely tensioned with great accuracy around the exterior circumference of the case. This is complemented by a screw-lock crown construction. The lugs of all versions are made of grade 5 titanium, with screws to attach the rubber diving strap for maximum security.

RM 025

TORQUE-LIMITING CROWN

This additional security system prevents accidental overwinding, which could cause damage to the winding stem or place extreme pressure on the barrel spring.

Finishing

Movement

• Anglage and polishing by hand
• Hand-polished locking sections
• Sapphire-blasted milled sections
• Lapped and polished contact points
• Burnished pivots

Steel parts

• Sapphire-blasted surfaces
• Anglage and polishing by hand

Wheels

• Concave chamfering with a diamond tool
• Circular-finished faces
• Rhodium plating (before cutting the teeth)
• Minimal corrections applied to the wheels in order to preserve geometry and performance.

Other features

BARREL PAWL WITH PROGRESSIVE RECOIL

This device permits an appreciable winding gain (circa 20%), especially during the start of winding. It is also helpful in evenly distributing the mainspring’s internal tension.

WINDING-BARREL TEETH AND THIRD-WHEEL PINION WITH CENTRAL INVOLUTE PROFILE

The central involute profile of the winding-barrel teeth provides an optimal pressure angle of 20°, which promotes effective rotary motion and compensates for possible variations in the operation of the going train. This, in turn, ensures excellent torque transmission and a distinct improvement in performance.

SPLINE AND EIGHT-POINTED SCREWS IN GRADE 5 TITANIUM FOR THE BRIDGES AND CASE

These types of screw permit better control of the torque applied to screws during assembly. These screws are unaffected by physical manipulation during assembly or disassembly and age well.

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